Gitea-Tools/docs/observability/sentry-integration.md

Self-hosted Sentry observability for the Gitea MCP server (#606)

Optional, off-by-default instrumentation that reports MCP runtime errors, fail-closed workflow blockers, lease / terminal-lock / stale-runtime collisions, and recurring watchdog check-ins to a self-hosted Sentry at https://sentry.prgs.cc/.

Gitea remains the source of truth. Sentry is observe-only. It never approves, merges, closes, or otherwise mutates Gitea workflow state, and it never bypasses leases, #332, workflow roles, or the MCP gates. Sentry alerts may only feed the sanctioned Gitea issue/comment path via the #612 incident bridge — never a direct write.

Implemented by sentry_observability.py.

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1. Create the Sentry project

1. Sign in to the self-hosted Sentry at https://sentry.prgs.cc/ (this is not Sentry Cloud — do not use *.ingest.sentry.io).
2. Create a new Python project named gitea-tools-mcp.
3. Open Settings → Projects → gitea-tools-mcp → Client Keys (DSN) and copy the DSN. It looks like https://<publickey>@sentry.prgs.cc/<project-id>.
4. Never commit the DSN. It is a runtime secret supplied via env var only.

2. Configure the environment

All configuration is env-var driven (see .env.example):

Variable	Purpose	Default
MCP_SENTRY_ENABLED	Master gate (1/true/yes/on). Required.	off
SENTRY_DSN	Self-hosted DSN. Required.	(empty)
SENTRY_ENVIRONMENT	local / dev / prod tag.	development
SENTRY_RELEASE	Release id (git SHA or version).	(none)
MCP_SENTRY_TRACES_SAMPLE_RATE	Perf-trace sample rate 0.0–1.0 (clamped).	0.0
MCP_SENTRY_ENABLE_LOGS	Forward Python logs as structured logs.	off

The feature stays completely off unless MCP_SENTRY_ENABLED is truthy and SENTRY_DSN is non-empty. With either missing, init_sentry() is a no-op, the SDK is never initialised, and no events are sent — existing tool behaviour and API-call patterns are unchanged.

Per-environment examples

# local (quiet: capture errors/blockers, no traces)
export MCP_SENTRY_ENABLED=1
export SENTRY_DSN="https://<key>@sentry.prgs.cc/<id>"
export SENTRY_ENVIRONMENT=local

# dev (light tracing + logs)
export MCP_SENTRY_ENABLED=1
export SENTRY_DSN="https://<key>@sentry.prgs.cc/<id>"
export SENTRY_ENVIRONMENT=dev
export MCP_SENTRY_TRACES_SAMPLE_RATE=0.2
export MCP_SENTRY_ENABLE_LOGS=1

# prod (errors/blockers + low-rate tracing, release-tagged)
export MCP_SENTRY_ENABLED=1
export SENTRY_DSN="https://<key>@sentry.prgs.cc/<id>"
export SENTRY_ENVIRONMENT=prod
export SENTRY_RELEASE="$(git rev-parse --short HEAD)"
export MCP_SENTRY_TRACES_SAMPLE_RATE=0.05

The optional SDK is pinned in requirements.txt (sentry-sdk==2.20.0). It is imported lazily: if the package is absent, the module still imports and every entry point is a safe no-op.

3. What is instrumented

Signal	Where	Notes
Startup init	gitea_mcp_server.py __main__, before mcp.run	Prints a redaction-safe status line to stderr.
Failing mutations (exceptions)	_audited(...) context manager	capture_exception with scrubbed tags.
Fail-closed blockers / failed mutations	_audit_pr_result(...) (BLOCKED/FAILED)	Structured capture_workflow_blocker event incl. the canonical next action when available (criterion 7).
Allocator watchdog check-ins	gitea_allocate_next_work tool	allocator_health, stale_lease_scan, terminal_lock_scan.
Namespace-health check-in	gitea_assess_mcp_namespace_health tool	namespace_health.

All capture paths are best-effort / fail open: a Sentry outage or capture error never breaks an MCP tool success path.

4. Cron / watchdog monitors

sentry_observability.MONITOR_SLUGS defines stable check-in slugs:

Registry key	Sentry monitor slug	Wired at
stale_lease_scan	gitea-mcp-stale-lease-scan	allocator run (global lease expiry)
terminal_lock_scan	gitea-mcp-terminal-lock-scan	allocator run (terminal-lock lookup)
allocator_health	gitea-mcp-allocator-health	allocator run
namespace_health	gitea-mcp-namespace-health	namespace-health probe
dashboard_freshness	gitea-mcp-dashboard-freshness	call monitor_checkin("dashboard_freshness", ...) from the dashboard refresh job (#605)
reconciler_cleanup	gitea-mcp-reconciler-cleanup	call monitor_checkin("reconciler_cleanup", ...) from the reconciler cleanup entrypoint

Create matching Cron monitors in Sentry with those slugs. Emit an in_progress check-in at job start and ok/error at completion via sentry_observability.monitor_checkin(slug_key, status).

5. Redaction guarantees (fail closed)

Redaction fails closed: if a field cannot be proven safe it is dropped rather than sent. The before_send (and before_send_log) hook scrub_event recursively redacts every outgoing event; on any error it drops the event entirely. Guarantees, proven by tests/test_sentry_observability.py:

• No tokens, passwords, keychain IDs, DSNs, cookies, or user:pass@host.
• No raw session-state or full prompt/comment bodies — session_id is only ever surfaced as a 12-char session_id_hash.
• No private config contents or raw credential headers.
• No full local filesystem paths — a worktree path collapses to a coarse worktree_category (author / reviewer / merger / reconciler / branches / root / other).
• Only the allowlisted tag keys in ALLOWED_TAG_KEYS are ever attached.

6. Coexistence with GlitchTip / the #612 incident bridge

This is the outbound path (MCP → Sentry SDK). It complements — it does not replace — the inbound incident_bridge.py (#612), which turns Sentry/GlitchTip observations into durable Gitea issues and incident_links rows.

• Prefer one observability path per environment. Point the MCP server's SENTRY_DSN at the same self-hosted gitea-tools-mcp project that the #612 bridge reconciles from, so an MCP-reported error and its Gitea issue line up.
• GlitchTip is Sentry-protocol compatible; if an existing GlitchTip DSN is in use, either migrate it to https://sentry.prgs.cc/ or document the split (MCP → Sentry, legacy → GlitchTip) explicitly for operators.
• The bridge remains the only sanctioned route from an alert back into Gitea workflow state.

7. Non-goals

• Sentry must not become the workflow source of truth.
• Sentry must not approve, merge, close, or mutate Gitea workflow state.
• Sentry must not bypass leases, #332, workflow roles, or the MCP gates.