Merge pull request 'Add logviewer: web UI for the ClickHouse log store' (#1) from benvin/initial into main

Reviewed-on: #1

.gitignore

@@ -0,0 +1,2 @@
+dist/
+logviewer

.pre-commit-config.yaml

@@ -0,0 +1,19 @@
+exclude: ^web/static/(jquery|bootstrap)[^/]*\.min\.(js|css)$
+
+repos:
+  - repo: https://github.com/pre-commit/pre-commit-hooks
+    rev: v4.6.0
+    hooks:
+      - id: trailing-whitespace
+      - id: end-of-file-fixer
+      - id: check-yaml
+      - id: check-merge-conflict
+      - id: mixed-line-ending
+        args: [--fix=lf]
+
+  - repo: https://github.com/dnephin/pre-commit-golang
+    rev: v0.5.1
+    hooks:
+      - id: go-fmt
+      - id: go-vet
+      - id: go-unit-tests

.woodpecker/build.yaml

@@ -0,0 +1,43 @@
+when:
+  - event: pull_request
+
+steps:
+  - name: build
+    image: golang:1.25
+    commands:
+      - make build
+    backend_options:
+      kubernetes:
+        serviceAccountName: default
+        resources:
+          requests:
+            memory: 512Mi
+            cpu: 1
+          limits:
+            memory: 2Gi
+            cpu: 2
+
+  # Validate the image builds without pushing. The CA-baked buildx plugin trusts
+  # the internal registry's CA; the plain woodpeckerci plugin fails x509 here.
+  - name: build-check
+    image: artifactapi.k8s.syd1.au.unkin.net/docker-internal/plugin-docker-buildx:latest
+    settings:
+      repo: artifactapi.k8s.syd1.au.unkin.net/docker-internal/logviewer
+      dockerfile: Dockerfile
+      dry_run: true
+      platforms: linux/amd64
+      build_args:
+        VERSION: ${CI_COMMIT_SHA}
+      buildkit_config: |
+        [registry."artifactapi.k8s.syd1.au.unkin.net"]
+          ca = ["/etc/docker/certs.d/artifactapi.k8s.syd1.au.unkin.net/ca.crt"]
+    backend_options:
+      kubernetes:
+        serviceAccountName: default
+        resources:
+          requests:
+            memory: 1Gi
+            cpu: 1
+          limits:
+            memory: 4Gi
+            cpu: 2

.woodpecker/pre-commit.yaml

@@ -0,0 +1,18 @@
+when:
+  - event: pull_request
+
+steps:
+  - name: pre-commit
+    image: git.unkin.net/unkin/almalinux9-gobuilder:20260606
+    commands:
+      - uvx pre-commit run --all-files
+    backend_options:
+      kubernetes:
+        serviceAccountName: default
+        resources:
+          requests:
+            memory: 512Mi
+            cpu: 1
+          limits:
+            memory: 2Gi
+            cpu: 2

.woodpecker/release.yaml

@@ -0,0 +1,30 @@
+when:
+  - event: tag
+    ref: refs/tags/v*
+
+steps:
+  - name: docker
+    image: artifactapi.k8s.syd1.au.unkin.net/docker-internal/plugin-docker-buildx:latest
+    settings:
+      registry: artifactapi.k8s.syd1.au.unkin.net
+      repo: artifactapi.k8s.syd1.au.unkin.net/docker-internal/logviewer
+      dockerfile: Dockerfile
+      platforms: linux/amd64
+      build_args:
+        VERSION: "${CI_COMMIT_TAG}"
+      buildkit_config: |
+        [registry."artifactapi.k8s.syd1.au.unkin.net"]
+          ca = ["/etc/docker/certs.d/artifactapi.k8s.syd1.au.unkin.net/ca.crt"]
+      tags:
+        - "${CI_COMMIT_TAG}"
+        - latest
+    backend_options:
+      kubernetes:
+        serviceAccountName: default
+        resources:
+          requests:
+            memory: 1Gi
+            cpu: 1
+          limits:
+            memory: 4Gi
+            cpu: 2

.woodpecker/test.yaml

@@ -0,0 +1,20 @@
+when:
+  - event: pull_request
+
+steps:
+  - name: test
+    image: golang:1.25
+    commands:
+      - go vet ./...
+      - test -z "$(gofmt -l .)"
+      - go test -v -race ./...
+    backend_options:
+      kubernetes:
+        serviceAccountName: default
+        resources:
+          requests:
+            memory: 512Mi
+            cpu: 1
+          limits:
+            memory: 2Gi
+            cpu: 2

Dockerfile

@@ -0,0 +1,18 @@
+FROM golang:1.25-alpine AS builder
+
+WORKDIR /build
+
+COPY go.mod ./
+RUN go mod download
+
+COPY . .
+
+ARG VERSION=dev
+RUN CGO_ENABLED=0 go build -ldflags="-s -w -X main.version=${VERSION}" -o logviewer .
+
+# distroless static ships ca-certificates and runs as an unprivileged user.
+FROM gcr.io/distroless/static-debian12:nonroot
+
+COPY --from=builder /build/logviewer /usr/local/bin/logviewer
+
+ENTRYPOINT ["logviewer"]

Makefile

@@ -0,0 +1,54 @@
+BINARY  := logviewer
+DIST    := dist
+VERSION := $(shell git describe --tags --always --dirty 2>/dev/null || echo dev)
+GOFLAGS := -ldflags="-s -w -X main.version=$(VERSION)"
+OS      ?= $(shell go env GOOS)
+ARCH    ?= $(shell go env GOARCH)
+
+.PHONY: all build test lint fmt vet clean docker patch minor major _tag
+
+all: build
+
+build:
+	CGO_ENABLED=0 GOOS=$(OS) GOARCH=$(ARCH) go build $(GOFLAGS) -o $(DIST)/$(BINARY) .
+
+test:
+	go test -v -race ./...
+
+vet:
+	go vet ./...
+
+lint:
+	golangci-lint run ./...
+
+fmt:
+	gofmt -w .
+
+clean:
+	rm -rf $(DIST)
+
+docker:
+	docker build --build-arg VERSION=$(VERSION) -t $(BINARY):$(VERSION) .
+
+# Bump helpers — reads the latest semver tag and creates the next one.
+# If no tag exists yet, starts from v0.0.0.
+_LATEST := $(shell git tag --sort=-v:refname | grep -E '^v[0-9]+\.[0-9]+\.[0-9]+$$' | head -1)
+_BASE   := $(if $(_LATEST),$(_LATEST),v0.0.0)
+_MAJ    := $(shell echo $(_BASE) | sed 's/^v//' | cut -d. -f1)
+_MIN    := $(shell echo $(_BASE) | sed 's/^v//' | cut -d. -f2)
+_PAT    := $(shell echo $(_BASE) | sed 's/^v//' | cut -d. -f3)
+
+patch:
+	@NEW=v$(_MAJ).$(_MIN).$(shell expr $(_PAT) + 1); \
+	git tag $$NEW && echo "Tagged $$NEW" && $(MAKE) _tag TAG=$$NEW
+
+minor:
+	@NEW=v$(_MAJ).$(shell expr $(_MIN) + 1).0; \
+	git tag $$NEW && echo "Tagged $$NEW" && $(MAKE) _tag TAG=$$NEW
+
+major:
+	@NEW=v$(shell expr $(_MAJ) + 1).0.0; \
+	git tag $$NEW && echo "Tagged $$NEW" && $(MAKE) _tag TAG=$$NEW
+
+_tag:
+	git push origin $(TAG)

README.md

@@ -1,3 +1,57 @@
 # logviewer
 
-Web UI for the ClickHouse log store: fuzzy find, tail and SQL-filter logs (logviewer.unkin.net)
+Web UI for the ClickHouse log store (`logs.raw`). Single Go binary with an
+embedded Bootstrap 3 + jQuery UI — no CDN assets, no build step.
+
+logviewer does **no authentication itself**. It runs behind oauth2-proxy at
+`logviewer.unkin.net`; the proxy is the auth boundary. Query safety relies on
+the readonly ClickHouse user (`logreader`) plus server-side guardrails:
+
+- **Time bounds are always enforced.** Missing `since`/`until` default to a
+  15m window ending now; windows wider than 72h (the table TTL) are rejected.
+  No request can scan the store unbounded.
+- **Everything is parameterized** (ClickHouse `param_*` bound parameters)
+  except the explicit raw `sql` fragment, which is parenthesised and ANDed
+  into the outer query — the enforced time bounds and `LIMIT` still apply,
+  and the readonly user can't write.
+- `max_execution_time=30` is set on every query.
+
+## Configuration
+
+| Env | Default | |
+|---|---|---|
+| `CH_URL` | `http://clickhouse-logs.logging.svc.cluster.local:8123` | ClickHouse HTTP endpoint |
+| `CH_USER` | `logreader` | readonly ClickHouse user |
+| `CH_PASSWORD` | (empty) | password for `CH_USER` |
+| `LISTEN_ADDR` | `:8080` | HTTP listen address |
+
+## API
+
+- `GET /api/query` — `since`/`until` (RFC3339, unix, or relative `15m`/`6h`/`1d`),
+  filters `namespace`/`host`/`pod`/`container`/`app`/`severity`/`stream`/`source`,
+  `q` (space-separated case-insensitive substring terms, all must match),
+  `sql` (raw WHERE fragment), `limit` (max 1000) / `offset`. Newest first.
+- `GET /api/tail` — same filters plus `cursor` (exclusive lower bound, unix ms).
+  Returns ascending rows and the next `cursor`. Stale cursors are clamped to
+  the last 15m.
+- `GET /api/facets` — top 20 namespaces / apps (`labels['app']`) / hosts by
+  row count in the window.
+- `GET /healthz` — ClickHouse ping.
+
+## UI
+
+Time-range picker (15m/1h/6h/1d/custom), facet dropdowns, debounced fuzzy
+search, toggleable raw-SQL box, paged log table with expandable rows
+(labels/fields), and a Tail mode (1s polling, autoscroll, pauses when you
+scroll up).
+
+## Development
+
+```sh
+make build   # dist/logviewer
+make test    # go test -race ./...
+make patch   # tag + push next vX.Y.Z → CI builds+pushes the image
+```
+
+Releases: pushing a `v*` tag builds the container and pushes it to
+`artifactapi.k8s.syd1.au.unkin.net/docker-internal/logviewer`.

go.mod

@@ -0,0 +1,3 @@
+module git.unkin.net/unkin/logviewer
+
+go 1.25

internal/server/clickhouse.go

@@ -0,0 +1,91 @@
+package server
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"io"
+	"net/http"
+	"net/url"
+	"strconv"
+	"strings"
+	"time"
+)
+
+// maxExecutionSeconds bounds every ClickHouse query server-side.
+const maxExecutionSeconds = 30
+
+type chClient struct {
+	url      string
+	user     string
+	password string
+	http     *http.Client
+}
+
+func newCHClient(chURL, user, password string) *chClient {
+	return &chClient{
+		url:      strings.TrimRight(chURL, "/"),
+		user:     user,
+		password: password,
+		http:     &http.Client{Timeout: (maxExecutionSeconds + 5) * time.Second},
+	}
+}
+
+type chColumn struct {
+	Name string `json:"name"`
+	Type string `json:"type"`
+}
+
+type chResult struct {
+	Meta []chColumn       `json:"meta"`
+	Data []map[string]any `json:"data"`
+	Rows int              `json:"rows"`
+}
+
+// query POSTs sql to the ClickHouse HTTP interface. Every value in params is
+// sent as a bound query parameter (param_<name>), never interpolated.
+func (c *chClient) query(ctx context.Context, sql string, params map[string]string) (*chResult, error) {
+	q := url.Values{}
+	q.Set("max_execution_time", strconv.Itoa(maxExecutionSeconds))
+	q.Set("output_format_json_quote_64bit_integers", "0")
+	for k, v := range params {
+		q.Set("param_"+k, v)
+	}
+
+	req, err := http.NewRequestWithContext(ctx, http.MethodPost, c.url+"/?"+q.Encode(), strings.NewReader(sql))
+	if err != nil {
+		return nil, err
+	}
+	req.Header.Set("X-ClickHouse-User", c.user)
+	req.Header.Set("X-ClickHouse-Key", c.password)
+	req.Header.Set("Content-Type", "text/plain")
+
+	resp, err := c.http.Do(req)
+	if err != nil {
+		return nil, err
+	}
+	defer resp.Body.Close()
+
+	body, err := io.ReadAll(io.LimitReader(resp.Body, 32<<20))
+	if err != nil {
+		return nil, err
+	}
+	if resp.StatusCode != http.StatusOK {
+		msg := strings.TrimSpace(string(body))
+		if len(msg) > 500 {
+			msg = msg[:500]
+		}
+		return nil, fmt.Errorf("clickhouse: %s: %s", resp.Status, msg)
+	}
+
+	var res chResult
+	if err := json.Unmarshal(body, &res); err != nil {
+		return nil, fmt.Errorf("clickhouse: decode response: %w", err)
+	}
+	return &res, nil
+}
+
+func (c *chClient) ping(ctx context.Context) error {
+	_, err := c.query(ctx, "SELECT 1 FORMAT JSON", nil)
+	return err
+}

internal/server/query.go

@@ -0,0 +1,218 @@
+package server
+
+import (
+	"fmt"
+	"net/url"
+	"strconv"
+	"strings"
+	"time"
+)
+
+const (
+	defaultWindow = 15 * time.Minute
+	// maxWindow matches the table TTL; anything wider scans nothing extra
+	// but signals a client bug, so reject it.
+	maxWindow    = 72 * time.Hour
+	defaultLimit = 100
+	maxLimit     = 1000
+	tailLimit    = 500
+)
+
+// filterColumns maps API query parameters to the column expression they filter
+// on. Only these names are ever accepted; values are always bound parameters.
+var filterColumns = []struct {
+	param  string
+	column string
+}{
+	{"namespace", "namespace"},
+	{"host", "host"},
+	{"pod", "pod"},
+	{"container", "container"},
+	{"app", "labels['app']"},
+	{"severity", "severity"},
+	{"stream", "stream"},
+	{"source", "source"},
+}
+
+const selectColumns = "timestamp, toUnixTimestamp64Milli(timestamp) AS ts_ms, host, source, namespace, pod, container, stream, severity, message, labels, fields"
+
+type timeRange struct {
+	since time.Time
+	until time.Time
+}
+
+// parseTimeRange enforces server-side time bounds: missing bounds default to a
+// 15m window ending now, and windows wider than maxWindow are rejected so a
+// query can never run unbounded over the store.
+func parseTimeRange(sinceStr, untilStr string, now time.Time) (timeRange, error) {
+	until := now
+	if untilStr != "" {
+		t, err := parseTime(untilStr, now)
+		if err != nil {
+			return timeRange{}, fmt.Errorf("invalid until: %w", err)
+		}
+		until = t
+	}
+	since := until.Add(-defaultWindow)
+	if sinceStr != "" {
+		t, err := parseTime(sinceStr, now)
+		if err != nil {
+			return timeRange{}, fmt.Errorf("invalid since: %w", err)
+		}
+		since = t
+	}
+	if !since.Before(until) {
+		return timeRange{}, fmt.Errorf("since (%s) must be before until (%s)", since.UTC().Format(time.RFC3339), until.UTC().Format(time.RFC3339))
+	}
+	if until.Sub(since) > maxWindow {
+		return timeRange{}, fmt.Errorf("time window %s exceeds maximum %s", until.Sub(since), maxWindow)
+	}
+	return timeRange{since: since, until: until}, nil
+}
+
+// parseTime accepts RFC3339, "2006-01-02 15:04:05", unix seconds/millis, and
+// relative durations like "15m" / "6h" / "1d" (meaning that long ago).
+func parseTime(s string, now time.Time) (time.Time, error) {
+	if t, err := time.Parse(time.RFC3339, s); err == nil {
+		return t, nil
+	}
+	if t, err := time.Parse("2006-01-02 15:04:05", s); err == nil {
+		return t.UTC(), nil
+	}
+	if n, err := strconv.ParseInt(s, 10, 64); err == nil {
+		if n > 1e12 {
+			return time.UnixMilli(n).UTC(), nil
+		}
+		return time.Unix(n, 0).UTC(), nil
+	}
+	if d, err := parseDuration(strings.TrimPrefix(s, "-")); err == nil {
+		return now.Add(-d), nil
+	}
+	return time.Time{}, fmt.Errorf("unrecognised time %q", s)
+}
+
+func parseDuration(s string) (time.Duration, error) {
+	if strings.HasSuffix(s, "d") {
+		n, err := strconv.Atoi(strings.TrimSuffix(s, "d"))
+		if err != nil {
+			return 0, err
+		}
+		return time.Duration(n) * 24 * time.Hour, nil
+	}
+	return time.ParseDuration(s)
+}
+
+func parseLimit(s string, def int) (int, error) {
+	if s == "" {
+		return def, nil
+	}
+	n, err := strconv.Atoi(s)
+	if err != nil || n < 1 {
+		return 0, fmt.Errorf("invalid limit %q", s)
+	}
+	if n > maxLimit {
+		n = maxLimit
+	}
+	return n, nil
+}
+
+func parseOffset(s string) (int, error) {
+	if s == "" {
+		return 0, nil
+	}
+	n, err := strconv.Atoi(s)
+	if err != nil || n < 0 {
+		return 0, fmt.Errorf("invalid offset %q", s)
+	}
+	return n, nil
+}
+
+// validateSQLFragment gates the raw WHERE fragment. Real safety comes from the
+// readonly ClickHouse user and the parameterized outer query; this only blocks
+// statement separators.
+func validateSQLFragment(frag string) error {
+	if strings.Contains(frag, ";") {
+		return fmt.Errorf("sql fragment must not contain ';'")
+	}
+	return nil
+}
+
+// encodeStringArray renders a ClickHouse Array(String) parameter value.
+func encodeStringArray(items []string) string {
+	var b strings.Builder
+	b.WriteByte('[')
+	for i, it := range items {
+		if i > 0 {
+			b.WriteByte(',')
+		}
+		b.WriteByte('\'')
+		b.WriteString(strings.ReplaceAll(strings.ReplaceAll(it, `\`, `\\`), `'`, `\'`))
+		b.WriteByte('\'')
+	}
+	b.WriteByte(']')
+	return b.String()
+}
+
+// whereClause builds the parameterized WHERE clause shared by the endpoints.
+// The time bounds are always present and always bound parameters, so no
+// filter or raw sql fragment can widen the scanned range.
+func whereClause(tr timeRange, form url.Values, params map[string]string, exclusiveSince bool) (string, error) {
+	var conds []string
+	params["since_ms"] = strconv.FormatInt(tr.since.UnixMilli(), 10)
+	params["until_ms"] = strconv.FormatInt(tr.until.UnixMilli(), 10)
+	sinceOp := ">="
+	if exclusiveSince {
+		sinceOp = ">"
+	}
+	conds = append(conds,
+		"timestamp "+sinceOp+" fromUnixTimestamp64Milli({since_ms:Int64})",
+		"timestamp < fromUnixTimestamp64Milli({until_ms:Int64})",
+	)
+
+	for _, f := range filterColumns {
+		if v := form.Get(f.param); v != "" {
+			p := "f_" + f.param
+			params[p] = v
+			conds = append(conds, fmt.Sprintf("%s = {%s:String}", f.column, p))
+		}
+	}
+
+	if q := strings.TrimSpace(form.Get("q")); q != "" {
+		tokens := strings.Fields(q)
+		params["q_tokens"] = encodeStringArray(tokens)
+		conds = append(conds, "arrayAll(t -> positionCaseInsensitive(message, t) > 0, {q_tokens:Array(String)})")
+	}
+
+	if frag := strings.TrimSpace(form.Get("sql")); frag != "" {
+		if err := validateSQLFragment(frag); err != nil {
+			return "", err
+		}
+		conds = append(conds, "( "+frag+" )")
+	}
+
+	return strings.Join(conds, "\n  AND "), nil
+}
+
+func buildQuerySQL(where string, limit, offset int) string {
+	return fmt.Sprintf(
+		"SELECT %s\nFROM logs.raw\nWHERE %s\nORDER BY timestamp DESC\nLIMIT %d OFFSET %d\nFORMAT JSON",
+		selectColumns, where, limit, offset)
+}
+
+func buildTailSQL(where string) string {
+	return fmt.Sprintf(
+		"SELECT %s\nFROM logs.raw\nWHERE %s\nORDER BY timestamp ASC\nLIMIT %d\nFORMAT JSON",
+		selectColumns, where, tailLimit)
+}
+
+func buildFacetsSQL(where string) string {
+	facet := func(name, expr string) string {
+		return fmt.Sprintf(
+			"SELECT * FROM (SELECT '%s' AS facet, %s AS value, count() AS n FROM logs.raw WHERE %s GROUP BY value ORDER BY n DESC LIMIT 20)",
+			name, expr, where)
+	}
+	return facet("namespace", "namespace") +
+		"\nUNION ALL\n" + facet("app", "labels['app']") +
+		"\nUNION ALL\n" + facet("host", "host") +
+		"\nFORMAT JSON"
+}

internal/server/server.go

@@ -0,0 +1,218 @@
+package server
+
+import (
+	"encoding/json"
+	"log"
+	"net/http"
+	"strconv"
+	"time"
+
+	"git.unkin.net/unkin/logviewer/web"
+)
+
+type Config struct {
+	CHURL      string
+	CHUser     string
+	CHPassword string
+	Version    string
+}
+
+type Server struct {
+	ch      *chClient
+	version string
+	now     func() time.Time
+	mux     *http.ServeMux
+}
+
+func New(cfg Config) *Server {
+	s := &Server{
+		ch:      newCHClient(cfg.CHURL, cfg.CHUser, cfg.CHPassword),
+		version: cfg.Version,
+		now:     time.Now,
+	}
+	s.routes()
+	return s
+}
+
+func (s *Server) routes() {
+	s.mux = http.NewServeMux()
+	s.mux.HandleFunc("GET /api/query", s.handleQuery)
+	s.mux.HandleFunc("GET /api/tail", s.handleTail)
+	s.mux.HandleFunc("GET /api/facets", s.handleFacets)
+	s.mux.HandleFunc("GET /healthz", s.handleHealthz)
+
+	s.mux.Handle("GET /", http.FileServerFS(web.FS))
+}
+
+func (s *Server) ServeHTTP(w http.ResponseWriter, r *http.Request) {
+	s.mux.ServeHTTP(w, r)
+}
+
+func writeJSON(w http.ResponseWriter, status int, v any) {
+	w.Header().Set("Content-Type", "application/json")
+	w.WriteHeader(status)
+	if err := json.NewEncoder(w).Encode(v); err != nil {
+		log.Printf("write response: %v", err)
+	}
+}
+
+func writeError(w http.ResponseWriter, status int, err error) {
+	writeJSON(w, status, map[string]string{"error": err.Error()})
+}
+
+func (s *Server) handleQuery(w http.ResponseWriter, r *http.Request) {
+	form := r.URL.Query()
+
+	tr, err := parseTimeRange(form.Get("since"), form.Get("until"), s.now())
+	if err != nil {
+		writeError(w, http.StatusBadRequest, err)
+		return
+	}
+	limit, err := parseLimit(form.Get("limit"), defaultLimit)
+	if err != nil {
+		writeError(w, http.StatusBadRequest, err)
+		return
+	}
+	offset, err := parseOffset(form.Get("offset"))
+	if err != nil {
+		writeError(w, http.StatusBadRequest, err)
+		return
+	}
+
+	params := map[string]string{}
+	where, err := whereClause(tr, form, params, false)
+	if err != nil {
+		writeError(w, http.StatusBadRequest, err)
+		return
+	}
+
+	res, err := s.ch.query(r.Context(), buildQuerySQL(where, limit, offset), params)
+	if err != nil {
+		writeError(w, http.StatusBadGateway, err)
+		return
+	}
+
+	writeJSON(w, http.StatusOK, map[string]any{
+		"rows":   res.Data,
+		"count":  len(res.Data),
+		"since":  tr.since.UTC().Format(time.RFC3339Nano),
+		"until":  tr.until.UTC().Format(time.RFC3339Nano),
+		"limit":  limit,
+		"offset": offset,
+	})
+}
+
+func (s *Server) handleTail(w http.ResponseWriter, r *http.Request) {
+	form := r.URL.Query()
+	now := s.now()
+
+	// The cursor is the exclusive lower bound in ms. It is clamped to the
+	// default window so a stale client can never trigger a wide scan.
+	cursor := now.Add(-10 * time.Second).UnixMilli()
+	if c := form.Get("cursor"); c != "" {
+		n, err := strconv.ParseInt(c, 10, 64)
+		if err != nil {
+			writeError(w, http.StatusBadRequest, err)
+			return
+		}
+		cursor = n
+	}
+	if min := now.Add(-defaultWindow).UnixMilli(); cursor < min {
+		cursor = min
+	}
+
+	// The tail bound is exclusive of the cursor so rows never repeat.
+	tr := timeRange{since: time.UnixMilli(cursor), until: now.Add(time.Second)}
+	params := map[string]string{}
+	where, err := whereClause(tr, form, params, true)
+	if err != nil {
+		writeError(w, http.StatusBadRequest, err)
+		return
+	}
+
+	res, err := s.ch.query(r.Context(), buildTailSQL(where), params)
+	if err != nil {
+		writeError(w, http.StatusBadGateway, err)
+		return
+	}
+
+	next := cursor
+	for _, row := range res.Data {
+		if ts, ok := numField(row, "ts_ms"); ok && ts > next {
+			next = ts
+		}
+	}
+
+	writeJSON(w, http.StatusOK, map[string]any{
+		"rows":   res.Data,
+		"count":  len(res.Data),
+		"cursor": next,
+	})
+}
+
+// numField reads an int64-ish field that ClickHouse may return as a JSON
+// number or (with 64-bit quoting) a string.
+func numField(row map[string]any, key string) (int64, bool) {
+	switch v := row[key].(type) {
+	case float64:
+		return int64(v), true
+	case string:
+		n, err := strconv.ParseInt(v, 10, 64)
+		return n, err == nil
+	case json.Number:
+		n, err := v.Int64()
+		return n, err == nil
+	}
+	return 0, false
+}
+
+func (s *Server) handleFacets(w http.ResponseWriter, r *http.Request) {
+	form := r.URL.Query()
+
+	tr, err := parseTimeRange(form.Get("since"), form.Get("until"), s.now())
+	if err != nil {
+		writeError(w, http.StatusBadRequest, err)
+		return
+	}
+
+	params := map[string]string{}
+	// Facets only take the time window; drop filters so dropdowns always
+	// show the full set for the window.
+	where, err := whereClause(tr, nil, params, false)
+	if err != nil {
+		writeError(w, http.StatusBadRequest, err)
+		return
+	}
+
+	res, err := s.ch.query(r.Context(), buildFacetsSQL(where), params)
+	if err != nil {
+		writeError(w, http.StatusBadGateway, err)
+		return
+	}
+
+	out := map[string][]map[string]any{
+		"namespaces": {},
+		"apps":       {},
+		"hosts":      {},
+	}
+	keys := map[string]string{"namespace": "namespaces", "app": "apps", "host": "hosts"}
+	for _, row := range res.Data {
+		facet, _ := row["facet"].(string)
+		key, ok := keys[facet]
+		if !ok {
+			continue
+		}
+		n, _ := numField(row, "n")
+		out[key] = append(out[key], map[string]any{"value": row["value"], "count": n})
+	}
+
+	writeJSON(w, http.StatusOK, out)
+}
+
+func (s *Server) handleHealthz(w http.ResponseWriter, r *http.Request) {
+	if err := s.ch.ping(r.Context()); err != nil {
+		writeError(w, http.StatusServiceUnavailable, err)
+		return
+	}
+	writeJSON(w, http.StatusOK, map[string]string{"status": "ok", "version": s.version})
+}

internal/server/server_test.go

@@ -0,0 +1,396 @@
+package server
+
+import (
+	"encoding/json"
+	"io"
+	"net/http"
+	"net/http/httptest"
+	"net/url"
+	"strconv"
+	"strings"
+	"testing"
+	"time"
+)
+
+var testNow = time.Date(2026, 8, 23, 12, 0, 0, 0, time.UTC)
+
+// mockCH captures the SQL body and bound parameters of each ClickHouse HTTP
+// request and returns a canned FORMAT JSON response.
+type mockCH struct {
+	*httptest.Server
+	lastSQL    string
+	lastParams url.Values
+	respond    func() (int, string)
+}
+
+func newMockCH(t *testing.T) *mockCH {
+	t.Helper()
+	m := &mockCH{respond: func() (int, string) { return 200, `{"meta":[],"data":[],"rows":0}` }}
+	m.Server = httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		body, _ := io.ReadAll(r.Body)
+		m.lastSQL = string(body)
+		m.lastParams = r.URL.Query()
+		code, resp := m.respond()
+		w.WriteHeader(code)
+		w.Write([]byte(resp))
+	}))
+	t.Cleanup(m.Close)
+	return m
+}
+
+func newTestServer(t *testing.T) (*Server, *mockCH) {
+	t.Helper()
+	ch := newMockCH(t)
+	s := New(Config{CHURL: ch.URL, CHUser: "logreader", CHPassword: "x", Version: "test"})
+	s.now = func() time.Time { return testNow }
+	return s, ch
+}
+
+func get(t *testing.T, s *Server, path string) *httptest.ResponseRecorder {
+	t.Helper()
+	req := httptest.NewRequest(http.MethodGet, path, nil)
+	rec := httptest.NewRecorder()
+	s.ServeHTTP(rec, req)
+	return rec
+}
+
+func boundMS(t *testing.T, params url.Values, name string) int64 {
+	t.Helper()
+	n, err := strconv.ParseInt(params.Get("param_"+name), 10, 64)
+	if err != nil {
+		t.Fatalf("param %s not an int64: %v", name, err)
+	}
+	return n
+}
+
+// --- time bound enforcement ---
+
+func TestQueryDefaultWindow(t *testing.T) {
+	s, ch := newTestServer(t)
+	rec := get(t, s, "/api/query")
+	if rec.Code != 200 {
+		t.Fatalf("status %d: %s", rec.Code, rec.Body)
+	}
+	since := boundMS(t, ch.lastParams, "since_ms")
+	until := boundMS(t, ch.lastParams, "until_ms")
+	if until != testNow.UnixMilli() {
+		t.Errorf("until = %d, want now (%d)", until, testNow.UnixMilli())
+	}
+	if until-since != defaultWindow.Milliseconds() {
+		t.Errorf("window = %dms, want default %dms", until-since, defaultWindow.Milliseconds())
+	}
+	for _, pred := range []string{
+		"timestamp >= fromUnixTimestamp64Milli({since_ms:Int64})",
+		"timestamp < fromUnixTimestamp64Milli({until_ms:Int64})",
+	} {
+		if !strings.Contains(ch.lastSQL, pred) {
+			t.Errorf("SQL missing enforced bound %q:\n%s", pred, ch.lastSQL)
+		}
+	}
+}
+
+func TestQueryExplicitWindow(t *testing.T) {
+	s, ch := newTestServer(t)
+	rec := get(t, s, "/api/query?since=2026-08-23T10:00:00Z&until=2026-08-23T11:00:00Z")
+	if rec.Code != 200 {
+		t.Fatalf("status %d: %s", rec.Code, rec.Body)
+	}
+	since := boundMS(t, ch.lastParams, "since_ms")
+	until := boundMS(t, ch.lastParams, "until_ms")
+	if until-since != time.Hour.Milliseconds() {
+		t.Errorf("window = %dms, want 1h", until-since)
+	}
+}
+
+func TestQueryRelativeSince(t *testing.T) {
+	s, ch := newTestServer(t)
+	if rec := get(t, s, "/api/query?since=6h"); rec.Code != 200 {
+		t.Fatalf("status %d: %s", rec.Code, rec.Body)
+	}
+	since := boundMS(t, ch.lastParams, "since_ms")
+	if want := testNow.Add(-6 * time.Hour).UnixMilli(); since != want {
+		t.Errorf("since = %d, want %d", since, want)
+	}
+}
+
+func TestQueryRejectsUnboundedWindow(t *testing.T) {
+	s, _ := newTestServer(t)
+	cases := []string{
+		"/api/query?since=1970-01-01T00:00:00Z",           // wider than maxWindow
+		"/api/query?since=2026-08-01T00:00:00Z&until=30d", // nonsense + wide
+		"/api/query?since=0",                              // epoch
+	}
+	for _, c := range cases {
+		if rec := get(t, s, c); rec.Code != http.StatusBadRequest {
+			t.Errorf("%s: status %d, want 400 (body %s)", c, rec.Code, rec.Body)
+		}
+	}
+}
+
+func TestQueryRejectsInvertedAndBadTimes(t *testing.T) {
+	s, _ := newTestServer(t)
+	cases := []string{
+		"/api/query?since=2026-08-23T11:00:00Z&until=2026-08-23T10:00:00Z",
+		"/api/query?since=yesterdayish",
+		"/api/query?until=not-a-time",
+	}
+	for _, c := range cases {
+		if rec := get(t, s, c); rec.Code != http.StatusBadRequest {
+			t.Errorf("%s: status %d, want 400", c, rec.Code)
+		}
+	}
+}
+
+// --- filters and fuzzy search ---
+
+func TestQueryFilterParamsAreBound(t *testing.T) {
+	s, ch := newTestServer(t)
+	rec := get(t, s, "/api/query?namespace=prod&app=encapi&severity=error")
+	if rec.Code != 200 {
+		t.Fatalf("status %d: %s", rec.Code, rec.Body)
+	}
+	if got := ch.lastParams.Get("param_f_namespace"); got != "prod" {
+		t.Errorf("param_f_namespace = %q", got)
+	}
+	if got := ch.lastParams.Get("param_f_app"); got != "encapi" {
+		t.Errorf("param_f_app = %q", got)
+	}
+	for _, pred := range []string{
+		"namespace = {f_namespace:String}",
+		"labels['app'] = {f_app:String}",
+		"severity = {f_severity:String}",
+	} {
+		if !strings.Contains(ch.lastSQL, pred) {
+			t.Errorf("SQL missing %q:\n%s", pred, ch.lastSQL)
+		}
+	}
+	// values must never be interpolated into the SQL text
+	if strings.Contains(ch.lastSQL, "prod") || strings.Contains(ch.lastSQL, "encapi") {
+		t.Errorf("filter value interpolated into SQL:\n%s", ch.lastSQL)
+	}
+}
+
+func TestQueryFuzzyTokens(t *testing.T) {
+	s, ch := newTestServer(t)
+	rec := get(t, s, "/api/query?q="+url.QueryEscape("timeout o'brien"))
+	if rec.Code != 200 {
+		t.Fatalf("status %d: %s", rec.Code, rec.Body)
+	}
+	if got, want := ch.lastParams.Get("param_q_tokens"), `['timeout','o\'brien']`; got != want {
+		t.Errorf("q_tokens = %q, want %q", got, want)
+	}
+	if !strings.Contains(ch.lastSQL, "arrayAll(t -> positionCaseInsensitive(message, t) > 0, {q_tokens:Array(String)})") {
+		t.Errorf("SQL missing fuzzy predicate:\n%s", ch.lastSQL)
+	}
+}
+
+// --- raw sql fragment ---
+
+func TestQuerySQLFragmentWrapped(t *testing.T) {
+	s, ch := newTestServer(t)
+	frag := "severity = 'error' AND message LIKE '%oom%'"
+	rec := get(t, s, "/api/query?sql="+url.QueryEscape(frag))
+	if rec.Code != 200 {
+		t.Fatalf("status %d: %s", rec.Code, rec.Body)
+	}
+	if !strings.Contains(ch.lastSQL, "AND ( "+frag+" )") {
+		t.Errorf("fragment not parenthesised inside WHERE:\n%s", ch.lastSQL)
+	}
+	// bounds and LIMIT still enforced around the fragment
+	if !strings.Contains(ch.lastSQL, "timestamp >= fromUnixTimestamp64Milli({since_ms:Int64})") {
+		t.Errorf("time bounds missing with sql fragment:\n%s", ch.lastSQL)
+	}
+	if !strings.Contains(ch.lastSQL, "LIMIT 100 OFFSET 0") {
+		t.Errorf("LIMIT missing with sql fragment:\n%s", ch.lastSQL)
+	}
+}
+
+func TestQuerySQLFragmentRejectsSemicolon(t *testing.T) {
+	s, _ := newTestServer(t)
+	rec := get(t, s, "/api/query?sql="+url.QueryEscape("1=1; DROP TABLE logs.raw"))
+	if rec.Code != http.StatusBadRequest {
+		t.Fatalf("status %d, want 400", rec.Code)
+	}
+}
+
+// --- limit / offset ---
+
+func TestQueryLimitCappedAndOffset(t *testing.T) {
+	s, ch := newTestServer(t)
+	rec := get(t, s, "/api/query?limit=999999&offset=200")
+	if rec.Code != 200 {
+		t.Fatalf("status %d: %s", rec.Code, rec.Body)
+	}
+	if !strings.Contains(ch.lastSQL, "LIMIT 1000 OFFSET 200") {
+		t.Errorf("limit not capped at %d:\n%s", maxLimit, ch.lastSQL)
+	}
+	for _, c := range []string{"limit=0", "limit=-5", "limit=abc", "offset=-1"} {
+		if rec := get(t, s, "/api/query?"+c); rec.Code != http.StatusBadRequest {
+			t.Errorf("%s: status %d, want 400", c, rec.Code)
+		}
+	}
+}
+
+// --- tail ---
+
+func tailRows(ts ...int64) string {
+	rows := make([]map[string]any, len(ts))
+	for i, v := range ts {
+		rows[i] = map[string]any{"ts_ms": v, "message": "m"}
+	}
+	b, _ := json.Marshal(map[string]any{"meta": []any{}, "data": rows, "rows": len(rows)})
+	return string(b)
+}
+
+func TestTailCursorAdvances(t *testing.T) {
+	s, ch := newTestServer(t)
+	cursor := testNow.Add(-5 * time.Second).UnixMilli()
+	ch.respond = func() (int, string) { return 200, tailRows(cursor+100, cursor+250) }
+
+	rec := get(t, s, "/api/tail?cursor="+strconv.FormatInt(cursor, 10))
+	if rec.Code != 200 {
+		t.Fatalf("status %d: %s", rec.Code, rec.Body)
+	}
+	if got := boundMS(t, ch.lastParams, "since_ms"); got != cursor {
+		t.Errorf("since_ms = %d, want cursor %d", got, cursor)
+	}
+	if !strings.Contains(ch.lastSQL, "timestamp > fromUnixTimestamp64Milli({since_ms:Int64})") {
+		t.Errorf("tail lower bound must be exclusive:\n%s", ch.lastSQL)
+	}
+	if !strings.Contains(ch.lastSQL, "ORDER BY timestamp ASC") {
+		t.Errorf("tail must be ascending:\n%s", ch.lastSQL)
+	}
+	var resp struct {
+		Cursor int64 `json:"cursor"`
+		Count  int   `json:"count"`
+	}
+	if err := json.Unmarshal(rec.Body.Bytes(), &resp); err != nil {
+		t.Fatal(err)
+	}
+	if resp.Cursor != cursor+250 {
+		t.Errorf("cursor = %d, want %d", resp.Cursor, cursor+250)
+	}
+	if resp.Count != 2 {
+		t.Errorf("count = %d, want 2", resp.Count)
+	}
+}
+
+func TestTailCursorUnchangedWhenNoRows(t *testing.T) {
+	s, _ := newTestServer(t)
+	cursor := testNow.Add(-3 * time.Second).UnixMilli()
+	rec := get(t, s, "/api/tail?cursor="+strconv.FormatInt(cursor, 10))
+	if rec.Code != 200 {
+		t.Fatalf("status %d: %s", rec.Code, rec.Body)
+	}
+	var resp struct {
+		Cursor int64 `json:"cursor"`
+	}
+	json.Unmarshal(rec.Body.Bytes(), &resp)
+	if resp.Cursor != cursor {
+		t.Errorf("cursor = %d, want unchanged %d", resp.Cursor, cursor)
+	}
+}
+
+func TestTailStaleCursorClamped(t *testing.T) {
+	s, ch := newTestServer(t)
+	stale := testNow.Add(-48 * time.Hour).UnixMilli()
+	rec := get(t, s, "/api/tail?cursor="+strconv.FormatInt(stale, 10))
+	if rec.Code != 200 {
+		t.Fatalf("status %d: %s", rec.Code, rec.Body)
+	}
+	if got, min := boundMS(t, ch.lastParams, "since_ms"), testNow.Add(-defaultWindow).UnixMilli(); got != min {
+		t.Errorf("stale cursor not clamped: since_ms = %d, want %d", got, min)
+	}
+}
+
+func TestTailBadCursor(t *testing.T) {
+	s, _ := newTestServer(t)
+	if rec := get(t, s, "/api/tail?cursor=nope"); rec.Code != http.StatusBadRequest {
+		t.Fatalf("status %d, want 400", rec.Code)
+	}
+}
+
+// --- facets ---
+
+func TestFacets(t *testing.T) {
+	s, ch := newTestServer(t)
+	ch.respond = func() (int, string) {
+		rows := []map[string]any{
+			{"facet": "namespace", "value": "prod", "n": 100},
+			{"facet": "namespace", "value": "logging", "n": 50},
+			{"facet": "app", "value": "encapi", "n": 70},
+			{"facet": "host", "value": "node1", "n": 30},
+		}
+		b, _ := json.Marshal(map[string]any{"meta": []any{}, "data": rows, "rows": len(rows)})
+		return 200, string(b)
+	}
+	rec := get(t, s, "/api/facets?since=1h")
+	if rec.Code != 200 {
+		t.Fatalf("status %d: %s", rec.Code, rec.Body)
+	}
+	for _, expr := range []string{"GROUP BY value", "labels['app']", "UNION ALL", "LIMIT 20"} {
+		if !strings.Contains(ch.lastSQL, expr) {
+			t.Errorf("facets SQL missing %q:\n%s", expr, ch.lastSQL)
+		}
+	}
+	var resp map[string][]map[string]any
+	if err := json.Unmarshal(rec.Body.Bytes(), &resp); err != nil {
+		t.Fatal(err)
+	}
+	if len(resp["namespaces"]) != 2 || len(resp["apps"]) != 1 || len(resp["hosts"]) != 1 {
+		t.Errorf("facet grouping wrong: %v", resp)
+	}
+	if resp["namespaces"][0]["value"] != "prod" {
+		t.Errorf("namespaces[0] = %v", resp["namespaces"][0])
+	}
+}
+
+func TestFacetsRejectsWideWindow(t *testing.T) {
+	s, _ := newTestServer(t)
+	if rec := get(t, s, "/api/facets?since=2020-01-01T00:00:00Z"); rec.Code != http.StatusBadRequest {
+		t.Fatalf("status %d, want 400", rec.Code)
+	}
+}
+
+// --- healthz + plumbing ---
+
+func TestHealthz(t *testing.T) {
+	s, ch := newTestServer(t)
+	if rec := get(t, s, "/healthz"); rec.Code != 200 {
+		t.Fatalf("status %d: %s", rec.Code, rec.Body)
+	}
+	ch.respond = func() (int, string) { return 500, "boom" }
+	if rec := get(t, s, "/healthz"); rec.Code != http.StatusServiceUnavailable {
+		t.Fatalf("status %d, want 503", rec.Code)
+	}
+}
+
+func TestQueryPropagatesCHError(t *testing.T) {
+	s, ch := newTestServer(t)
+	ch.respond = func() (int, string) { return 400, "Code: 62. DB::Exception: Syntax error" }
+	rec := get(t, s, "/api/query?sql="+url.QueryEscape("not valid sql"))
+	if rec.Code != http.StatusBadGateway {
+		t.Fatalf("status %d, want 502", rec.Code)
+	}
+	if !strings.Contains(rec.Body.String(), "Syntax error") {
+		t.Errorf("CH error not surfaced: %s", rec.Body)
+	}
+}
+
+func TestMaxExecutionTimeSet(t *testing.T) {
+	s, ch := newTestServer(t)
+	if rec := get(t, s, "/api/query"); rec.Code != 200 {
+		t.Fatalf("status %d", rec.Code)
+	}
+	if got := ch.lastParams.Get("max_execution_time"); got != "30" {
+		t.Errorf("max_execution_time = %q, want 30", got)
+	}
+}
+
+func TestIndexServed(t *testing.T) {
+	s, _ := newTestServer(t)
+	rec := get(t, s, "/")
+	if rec.Code != 200 || !strings.Contains(rec.Body.String(), "logviewer") {
+		t.Fatalf("index not served: %d", rec.Code)
+	}
+}

main.go

@@ -0,0 +1,47 @@
+package main
+
+import (
+	"log"
+	"net/http"
+	"os"
+	"time"
+
+	"git.unkin.net/unkin/logviewer/internal/server"
+)
+
+var version = "dev"
+
+func envOr(key, def string) string {
+	if v := os.Getenv(key); v != "" {
+		return v
+	}
+	return def
+}
+
+func main() {
+	chURL := envOr("CH_URL", "http://clickhouse-logs.logging.svc.cluster.local:8123")
+	chUser := envOr("CH_USER", "logreader")
+	chPassword := os.Getenv("CH_PASSWORD")
+	addr := envOr("LISTEN_ADDR", ":8080")
+
+	srv := server.New(server.Config{
+		CHURL:      chURL,
+		CHUser:     chUser,
+		CHPassword: chPassword,
+		Version:    version,
+	})
+
+	hs := &http.Server{
+		Addr:              addr,
+		Handler:           srv,
+		ReadHeaderTimeout: 10 * time.Second,
+		ReadTimeout:       60 * time.Second,
+		WriteTimeout:      60 * time.Second,
+		IdleTimeout:       120 * time.Second,
+	}
+
+	log.Printf("logviewer %s listening on %s (clickhouse %s as %s)", version, addr, chURL, chUser)
+	if err := hs.ListenAndServe(); err != nil {
+		log.Fatal(err)
+	}
+}

web/embed.go

@@ -0,0 +1,7 @@
+// Package web embeds the UI so the server binary is self-contained.
+package web
+
+import "embed"
+
+//go:embed index.html static
+var FS embed.FS

web/index.html

@@ -0,0 +1,122 @@
+<!DOCTYPE html>
+<html lang="en">
+<head>
+  <meta charset="utf-8">
+  <meta name="viewport" content="width=device-width, initial-scale=1">
+  <title>logviewer</title>
+  <link rel="stylesheet" href="/static/bootstrap.min.css">
+  <link rel="stylesheet" href="/static/logviewer.css">
+</head>
+<body>
+  <nav class="navbar navbar-inverse navbar-static-top">
+    <div class="container-fluid">
+      <div class="navbar-header">
+        <a class="navbar-brand" href="/">logviewer</a>
+      </div>
+      <p class="navbar-text navbar-right" id="status-text"></p>
+    </div>
+  </nav>
+
+  <div class="container-fluid">
+    <form id="search-form" onsubmit="return false;">
+      <div class="row">
+        <div class="col-md-4">
+          <div class="btn-group" role="group" id="range-buttons">
+            <button type="button" class="btn btn-default range-btn active" data-range="15m">15m</button>
+            <button type="button" class="btn btn-default range-btn" data-range="1h">1h</button>
+            <button type="button" class="btn btn-default range-btn" data-range="6h">6h</button>
+            <button type="button" class="btn btn-default range-btn" data-range="1d">1d</button>
+            <button type="button" class="btn btn-default range-btn" data-range="custom">custom</button>
+          </div>
+        </div>
+        <div class="col-md-5">
+          <div class="input-group">
+            <input type="text" class="form-control" id="q" placeholder="fuzzy search (space-separated terms, all must match)">
+            <span class="input-group-btn">
+              <button class="btn btn-primary" type="button" id="search-btn">Search</button>
+            </span>
+          </div>
+        </div>
+        <div class="col-md-3 text-right">
+          <button type="button" class="btn btn-default" id="sql-toggle">SQL</button>
+          <button type="button" class="btn btn-default" id="tail-toggle">Tail</button>
+        </div>
+      </div>
+
+      <div class="row" id="custom-range" style="display:none; margin-top:8px;">
+        <div class="col-md-3">
+          <div class="input-group">
+            <span class="input-group-addon">since</span>
+            <input type="datetime-local" class="form-control" id="since-input" step="1">
+          </div>
+        </div>
+        <div class="col-md-3">
+          <div class="input-group">
+            <span class="input-group-addon">until</span>
+            <input type="datetime-local" class="form-control" id="until-input" step="1">
+          </div>
+        </div>
+      </div>
+
+      <div class="row" id="sql-row" style="display:none; margin-top:8px;">
+        <div class="col-md-12">
+          <textarea class="form-control mono" id="sql" rows="2"
+            placeholder="raw WHERE fragment, e.g. severity = 'error' AND message LIKE '%timeout%' (runs as readonly user, time bounds and LIMIT always enforced)"></textarea>
+        </div>
+      </div>
+
+      <div class="row" style="margin-top:8px;">
+        <div class="col-md-2"><select class="form-control" id="f-namespace"><option value="">namespace</option></select></div>
+        <div class="col-md-2"><select class="form-control" id="f-app"><option value="">app</option></select></div>
+        <div class="col-md-2"><select class="form-control" id="f-host"><option value="">host</option></select></div>
+        <div class="col-md-2"><input type="text" class="form-control" id="f-pod" placeholder="pod"></div>
+        <div class="col-md-1"><input type="text" class="form-control" id="f-container" placeholder="container"></div>
+        <div class="col-md-2">
+          <select class="form-control" id="f-severity">
+            <option value="">severity</option>
+            <option>fatal</option><option>error</option><option>warn</option>
+            <option>info</option><option>debug</option><option>trace</option>
+          </select>
+        </div>
+        <div class="col-md-1">
+          <select class="form-control" id="f-stream">
+            <option value="">stream</option>
+            <option>stdout</option><option>stderr</option>
+          </select>
+        </div>
+      </div>
+    </form>
+
+    <div class="row" style="margin-top:10px;">
+      <div class="col-md-6">
+        <p id="result-info" class="text-muted"></p>
+      </div>
+      <div class="col-md-6 text-right" id="pager">
+        <div class="btn-group">
+          <button type="button" class="btn btn-default btn-sm" id="prev-btn" disabled>&laquo; newer</button>
+          <button type="button" class="btn btn-default btn-sm" id="next-btn" disabled>older &raquo;</button>
+        </div>
+        <select id="page-size" class="btn btn-default btn-sm">
+          <option>100</option><option>200</option><option>500</option><option>1000</option>
+        </select>
+      </div>
+    </div>
+
+    <table class="table table-condensed table-hover" id="log-table">
+      <thead>
+        <tr>
+          <th class="col-ts">timestamp (UTC)</th>
+          <th class="col-src">namespace / pod</th>
+          <th class="col-sev">severity</th>
+          <th>message</th>
+        </tr>
+      </thead>
+      <tbody id="log-body"></tbody>
+    </table>
+  </div>
+
+  <script src="/static/jquery.min.js"></script>
+  <script src="/static/bootstrap.min.js"></script>
+  <script src="/static/app.js"></script>
+</body>
+</html>

web/static/app.js

@@ -0,0 +1,253 @@
+(function () {
+  'use strict';
+
+  var state = {
+    range: '15m',
+    offset: 0,
+    limit: 100,
+    tail: false,
+    tailTimer: null,
+    tailCursor: null,
+    tailPaused: false,
+    lastCount: 0
+  };
+
+  var SEV_CLASS = {
+    fatal: 'label-danger', crit: 'label-danger', critical: 'label-danger',
+    error: 'label-danger', err: 'label-danger',
+    warn: 'label-warning', warning: 'label-warning',
+    info: 'label-info',
+    debug: 'label-default', trace: 'label-default'
+  };
+
+  function sevLabel(sev) {
+    var cls = SEV_CLASS[(sev || '').toLowerCase()] || 'label-default';
+    return $('<span>').addClass('label ' + cls).text(sev || '-');
+  }
+
+  function timeParams() {
+    var p = {};
+    if (state.range === 'custom') {
+      var s = $('#since-input').val(), u = $('#until-input').val();
+      if (s) p.since = new Date(s).toISOString();
+      if (u) p.until = new Date(u).toISOString();
+    } else {
+      p.since = state.range;
+    }
+    return p;
+  }
+
+  function filterParams() {
+    var p = {};
+    var map = {
+      namespace: '#f-namespace', app: '#f-app', host: '#f-host',
+      pod: '#f-pod', container: '#f-container',
+      severity: '#f-severity', stream: '#f-stream'
+    };
+    Object.keys(map).forEach(function (k) {
+      var v = $(map[k]).val();
+      if (v) p[k] = v;
+    });
+    var q = $('#q').val().trim();
+    if (q) p.q = q;
+    if ($('#sql-row').is(':visible')) {
+      var sql = $('#sql').val().trim();
+      if (sql) p.sql = sql;
+    }
+    return p;
+  }
+
+  function setStatus(msg, isError) {
+    $('#status-text').text(msg || '').toggleClass('text-danger', !!isError);
+  }
+
+  function renderRow(row, tbody) {
+    var src = (row.namespace || '-') + ' / ' + (row.pod || '-');
+    var tr = $('<tr>').addClass('log-row')
+      .append($('<td>').addClass('col-ts').text(row.timestamp))
+      .append($('<td>').addClass('col-src').text(src))
+      .append($('<td>').addClass('col-sev').append(sevLabel(row.severity)))
+      .append($('<td>').addClass('msg').text(row.message));
+    tr.data('row', row);
+    tbody.append(tr);
+  }
+
+  function kvTable(title, obj) {
+    var keys = Object.keys(obj || {});
+    if (!keys.length) return null;
+    var t = $('<table>').addClass('table table-condensed detail-table');
+    t.append($('<caption>').text(title));
+    keys.sort().forEach(function (k) {
+      t.append($('<tr>').append($('<th>').text(k)).append($('<td>').text(obj[k])));
+    });
+    return t;
+  }
+
+  function toggleDetail(tr) {
+    var next = tr.next();
+    if (next.hasClass('detail-row')) { next.remove(); return; }
+    var row = tr.data('row');
+    var cell = $('<td>').attr('colspan', 4);
+    var meta = {
+      host: row.host, source: row.source, namespace: row.namespace,
+      pod: row.pod, container: row.container, stream: row.stream
+    };
+    [kvTable('meta', meta), kvTable('labels', row.labels), kvTable('fields', row.fields)]
+      .forEach(function (t) { if (t) cell.append(t); });
+    tr.after($('<tr>').addClass('detail-row').append(cell));
+  }
+
+  function renderRows(rows, append) {
+    var tbody = $('#log-body');
+    if (!append) tbody.empty();
+    rows.forEach(function (r) { renderRow(r, tbody); });
+  }
+
+  function runQuery() {
+    var params = $.extend({ limit: state.limit, offset: state.offset }, timeParams(), filterParams());
+    setStatus('loading...');
+    $.getJSON('/api/query', params)
+      .done(function (res) {
+        renderRows(res.rows, false);
+        state.lastCount = res.count;
+        setStatus('');
+        $('#result-info').text(
+          res.count + ' rows (' + res.since + ' → ' + res.until + '), offset ' + res.offset);
+        $('#prev-btn').prop('disabled', state.offset === 0);
+        $('#next-btn').prop('disabled', res.count < state.limit);
+      })
+      .fail(function (xhr) {
+        setStatus((xhr.responseJSON && xhr.responseJSON.error) || 'query failed', true);
+      });
+  }
+
+  function tailTick() {
+    if (state.tailPaused) return;
+    var params = $.extend({}, filterParams());
+    if (state.tailCursor !== null) params.cursor = state.tailCursor;
+    $.getJSON('/api/tail', params)
+      .done(function (res) {
+        state.tailCursor = res.cursor;
+        if (res.rows.length) {
+          renderRows(res.rows, true);
+          // keep the DOM bounded during long tails
+          var body = $('#log-body');
+          var extra = body.children('.log-row').length - 2000;
+          if (extra > 0) body.children().slice(0, extra * 2).remove();
+          if (!state.tailPaused) {
+            window.scrollTo(0, document.body.scrollHeight);
+          }
+        }
+        setStatus('tailing (cursor ' + res.cursor + ')');
+      })
+      .fail(function (xhr) {
+        setStatus((xhr.responseJSON && xhr.responseJSON.error) || 'tail failed', true);
+      });
+  }
+
+  function startTail() {
+    state.tail = true;
+    state.tailCursor = null;
+    state.tailPaused = false;
+    $('#log-body').empty();
+    $('#tail-toggle').addClass('active');
+    $('#pager button, #page-size').prop('disabled', true);
+    state.tailTimer = setInterval(tailTick, 1000);
+    tailTick();
+  }
+
+  function stopTail() {
+    state.tail = false;
+    clearInterval(state.tailTimer);
+    state.tailTimer = null;
+    $('#tail-toggle').removeClass('active');
+    $('#pager button, #page-size').prop('disabled', false);
+    setStatus('');
+  }
+
+  function refresh() {
+    if (state.tail) { stopTail(); startTail(); return; }
+    state.offset = 0;
+    runQuery();
+  }
+
+  function loadFacets() {
+    $.getJSON('/api/facets', timeParams()).done(function (res) {
+      var fill = function (sel, items, placeholder) {
+        var cur = $(sel).val();
+        var el = $(sel).empty().append($('<option>').val('').text(placeholder));
+        (items || []).forEach(function (it) {
+          el.append($('<option>').val(it.value).text(it.value + ' (' + it.count + ')'));
+        });
+        el.val(cur);
+        if (el.val() === null) el.val('');
+      };
+      fill('#f-namespace', res.namespaces, 'namespace');
+      fill('#f-app', res.apps, 'app');
+      fill('#f-host', res.hosts, 'host');
+    });
+  }
+
+  // --- events ---
+
+  $('#range-buttons').on('click', '.range-btn', function () {
+    $('.range-btn').removeClass('active');
+    $(this).addClass('active');
+    state.range = $(this).data('range');
+    $('#custom-range').toggle(state.range === 'custom');
+    if (state.range !== 'custom') { loadFacets(); refresh(); }
+  });
+
+  $('#custom-range input').on('change', function () {
+    loadFacets();
+    refresh();
+  });
+
+  $('#search-btn').on('click', refresh);
+  $('#search-form').on('change', 'select', refresh);
+  $('#search-form').on('keypress', 'input', function (e) {
+    if (e.which === 13) { e.preventDefault(); refresh(); }
+  });
+
+  var debounce = null;
+  $('#q').on('input', function () {
+    clearTimeout(debounce);
+    debounce = setTimeout(refresh, 300);
+  });
+
+  $('#sql-toggle').on('click', function () {
+    $(this).toggleClass('active');
+    $('#sql-row').toggle($(this).hasClass('active'));
+  });
+
+  $('#tail-toggle').on('click', function () {
+    if (state.tail) stopTail(); else startTail();
+  });
+
+  $('#log-body').on('click', 'tr.log-row', function () { toggleDetail($(this)); });
+
+  $('#prev-btn').on('click', function () {
+    state.offset = Math.max(0, state.offset - state.limit);
+    runQuery();
+  });
+  $('#next-btn').on('click', function () {
+    state.offset += state.limit;
+    runQuery();
+  });
+  $('#page-size').on('change', function () {
+    state.limit = parseInt($(this).val(), 10);
+    state.offset = 0;
+    runQuery();
+  });
+
+  // Pause tail autoscroll when the user scrolls up; resume at the bottom.
+  $(window).on('scroll', function () {
+    if (!state.tail) return;
+    var atBottom = window.innerHeight + window.scrollY >= document.body.scrollHeight - 40;
+    state.tailPaused = !atBottom;
+    if (state.tailPaused) setStatus('tail paused (scroll to bottom to resume)');
+  });
+
+  loadFacets();
+  runQuery();
+})();

web/static/logviewer.css

@@ -0,0 +1,14 @@
+.mono, #log-table td.msg, #log-table td.col-ts, .detail-table td {
+  font-family: Menlo, Monaco, Consolas, "Liberation Mono", monospace;
+  font-size: 12px;
+}
+#log-table td { vertical-align: top; word-break: break-all; }
+#log-table .col-ts { white-space: nowrap; width: 190px; }
+#log-table .col-src { width: 260px; }
+#log-table .col-sev { width: 80px; }
+#log-table tbody tr.log-row { cursor: pointer; }
+#log-table tr.detail-row td { background: #f7f7f9; }
+.detail-table { margin-bottom: 4px; }
+.detail-table th { width: 160px; }
+.sev-error, .sev-fatal, .sev-crit { }
+#tail-toggle.active, #sql-toggle.active { background: #337ab7; color: #fff; }