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logarchiver/docs/fetch.md
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Initial implementation: NATS->S3 archiver + search/retrieve CLI
logarchiver replaces the plain Vector archiver leg of the centralized
logging stack (argocd-apps #296) with a Go service that archives raw logs
from NATS JetStream to S3 as zstd-compressed, OpenPGP-encrypted, indexed
objects, plus an operator CLI to search the index and retrieve/decrypt
archived logs. It adds the things that outgrew Vector: zstd compression,
encryption keyed from Ben's Vault GPG secrets engine, a searchable
ClickHouse index, and sink-conditional acks (a batch is acknowledged to
JetStream only after the object is durably in S3 AND indexed).

Service (`logarchiver run`):
- Durable JetStream pull consumer (stream LOGS, durable archiver, subject
  filter default logs.k8s.vault.>), explicit acks, independent offsets.
- Batch per subject by size/count/time -> NDJSON -> zstd -> encrypt -> S3
  PUT -> ClickHouse index row -> ack. On any failure the batch is Nak'd and
  redelivered, so nothing is lost on a sink outage.
- Encryption is a wrapped-DEK envelope (container LARC1): the bulk is
  AES-256-GCM framed under a random data key, and only that 32-byte key is
  OpenPGP-encrypted to the engine's public key. This is because the Vault
  GPG engine does whole-payload decrypt only; retrieval round-trips just the
  tiny wrapped key regardless of object size. Public key fetched from the
  engine or a mounted file (configurable); key fingerprint recorded per
  object; periodic pubkey refresh for rotation.
- Prometheus metrics, structured slog, graceful drain on shutdown.

CLI:
- `search` queries the index (subject/host/time) and lists matching objects.
- `fetch` downloads, decrypts via the Vault GPG engine, unzstds and emits
  NDJSON (optionally re-filtered by host/time).
- `init-schema` creates/prints the ClickHouse archive_index DDL.
- cobra `completion` subcommands.

Config via file+env (k8s-friendly, secrets from env), boundaries (NATS/S3/
ClickHouse/Vault) behind interfaces with unit tests (config, batching,
host/subject extraction, crypto roundtrip with a test key, ack-after-persist
with fakes, search query building). go build/vet/test -race clean;
golangci-lint v2 clean. Woodpecker CI: build/test/pre-commit on PR; on v*
tag a container image plus a Gitea binary release + rpm-internal RPM. Docs
per subcommand + architecture + retrieval runbook + deployment drop-in.

Claude-Session: https://claude.ai/code/session_015ur3i7D2azsMAWTSVABApv
2026-07-27 23:22:40 +10:00

1.6 KiB

logarchiver fetch

Download, decrypt, and decompress archived objects to plain NDJSON.

logarchiver fetch [object-key ...] [flags]

Objects are selected either by explicit object-key arguments, or — when no keys are given — by the same --subject/--host/--from/--to query used by search. When --host/--from/--to are supplied they ALSO re-filter the emitted events to just the matching lines.

Flags

Flag Meaning
-o, --output - for stdout (default), or a directory to write one NDJSON file per object.
--subject/--host/--from/--to/--limit Object selection (same as search) when no keys are given; host/time also re-filter emitted lines.

How decryption works

For each object, fetch reads the object header to learn which Vault GPG key wrapped it, sends only the small wrapped data key to the engine's gpg/decrypt/<name> endpoint, recovers the data key, and streams the AES-GCM frames through local decryption + zstd to emit NDJSON. See the retrieval runbook for the full design and required creds (S3 read, internal CA, ambient VAULT_TOKEN/~/.vault-token).

Examples

# Straight to stdout by key:
logarchiver fetch archive/logs.k8s.vault._/2026/07/27/20260727T101500Z-ab12cd34.ndjson.zst.larc -o -

# From a query, re-filtered to host db-1 in the last 24h, into ./out:
logarchiver fetch --subject 'logs.vm.*' --host db-1 --from -24h -o ./out

Exit status is non-zero if any selected object fails; per-object errors are reported on stderr and the remaining objects are still processed.