node-lookup/README.md

node-lookup tools

PuppetDB CLIs and one proxy daemon, shipped together in a single RPM:

• node-lookup — query and filter PuppetDB node facts.
• pburl — print each host's Puppetboard node-page URL.
• pblastreport — print each host's last Puppet report time + Puppetboard URL.
• pdbmux — merging HTTP proxy over two PuppetDBs (see below).

See AGENTS.md for the CLI tools' flags, config, and internals. This README covers pdbmux.

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pdbmux — merging PuppetDB proxy

What

pdbmux is a small HTTP daemon that fronts two PuppetDB backends and serves a single, merged PuppetDB v4 query surface on one address. Point node-lookup, pblastreport, or anything else at pdbmux instead of a raw PuppetDB and it sees one consistent view spanning both.

Why

During the VM→k8s Puppet migration there are two PuppetDBs:

• old — the legacy Consul-registered http://puppetdbapi.service.consul:8080
• new — the k8s https://puppetdb.k8s.syd1.au.unkin.net (TLS terminated at the gateway; backends are plain PuppetDB on 8080)

Nodes move from old to new as they migrate, so at any moment a given node's current data lives in exactly one of them. pdbmux merges both so consumers don't have to know (or query twice) which PuppetDB a node currently lives in.

Endpoints

pdbmux proxies GET requests only. The query param (PuppetDB AST JSON, not PQL) is forwarded verbatim.

Path	Behaviour
GET /pdb/query/v4/nodes	Fan out to both backends, dedupe by certname, keep the record with the newer report_timestamp.
GET /pdb/query/v4/facts	Fan out to both, and per certname keep all facts from the backend that owns that node (see merge semantics).
GET /pdb/query/v4/* (any other)	Transparently proxied to the primary backend, unmerged, streamed verbatim.
GET /healthz	Per-backend reachability. 200 {"status":"ok"} if all reachable, 200 degraded if some fail, 503 down if all fail.

Fan-out is concurrent. If one backend errors or times out, pdbmux serves the survivor's results and logs a warning; a merged endpoint only returns 502 when every backend fails. Response records are passed through as raw JSON so unknown fields survive untouched.

Merge semantics

• /nodes — dedupe by certname; the record with the strictly-newer report_timestamp wins. On a tie (or when a node exists in only one backend), the preferred backend's record is kept.
• /facts — node-level granularity. For a certname present in both backends, pdbmux keeps all of that node's facts from one backend and drops the other's, chosen by the merge strategy:
  • freshness (default) — attribute each certname to whichever backend holds its newer report_timestamp. pdbmux derives this from a per-certname freshness map built by querying /nodes from both backends, cached for freshness_ttl (default 30s). Ties/fallbacks use prefer.
  • static — always keep the prefer backend's facts for shared nodes. No extra /nodes query.
  • A node present in only one backend always appears (falls back to whichever backend actually returned facts for it).

Config

Precedence (lowest → highest): defaults < config file < env vars (PDBMUX_*) < flags.

Config file: $XDG_CONFIG_HOME/pdbmux/config.yaml (as an RPM/systemd service: /etc/pdbmux/config.yaml).

# ~/.config/pdbmux/config.yaml  (or /etc/pdbmux/config.yaml under systemd)
listen: ":8080"
backends:
  - name: old
    url: http://puppetdbapi.service.consul:8080
  - name: new
    url: https://puppetdb.k8s.syd1.au.unkin.net
primary: new          # backend used for non-merged /pdb/query/v4/* pass-through
merge: freshness      # freshness | static
prefer: new           # winner on ties / static merge / fallback
timeout: 10s          # per-upstream request timeout
freshness_ttl: 30s    # freshness-map cache TTL (freshness merge only)

backends[*].url is a base URL (scheme://host[:port]), without the /pdb/query/v4/... path — pdbmux appends the path per request.

Env var	Overrides
PDBMUX_LISTEN	listen
PDBMUX_PRIMARY	primary
PDBMUX_MERGE	merge
PDBMUX_PREFER	prefer
PDBMUX_TIMEOUT	timeout (Go duration, e.g. 10s)
PDBMUX_FRESHNESS_TTL	freshness_ttl
PDBMUX_BACKENDS	whole backend list, as name=url,name=url

Flags: --listen, --primary, --merge.

Running

pdbmux                 # start the proxy (serve is the default action)
pdbmux serve           # explicit
pdbmux config init     # write a default config file
pdbmux config show     # print active config after all overrides
pdbmux version

Point a consumer at it:

node-lookup --url http://localhost:8080/pdb/query/v4/facts -R
NODE_LOOKUP_URL=http://localhost:8080/pdb/query/v4/facts pblastreport somehost

Deployment

The RPM installs /usr/bin/pdbmux plus a systemd unit at /usr/lib/systemd/system/pdbmux.service (reads /etc/pdbmux/config.yaml):

systemctl enable --now pdbmux
curl -s localhost:8080/healthz

Suited to run as an RPM-managed daemon on a VM alongside the existing Puppet infra during migration; the same static binary is container-ready for a future k8s deployment (single listener, /healthz liveness/readiness probe, config via PDBMUX_* env).