MCPg v0.6.5 — release notes

Released: 2026-06-30 Tool surface: 246 tools across 19 capability buckets Tests: 2552 pass (PG 14 / 15 / 16 / 17 / 18 / 19) CI: PG 14-19 + an experimental WarehousePG lane

This is a patch-level bump (0.6.4 → 0.6.5) carrying a single headline feature — the multi-database selector (roadmap 13.1). Every addition is backward-compatible: the primary-only path is byte-for-byte unchanged when the new env var is unset, so existing deployments upgrade with no configuration changes.

Headline: one server, multiple databases (read-only secondaries)

A single MCPg server can now serve multiple databases. The primary (MCPG_DATABASE_URL) stays the default target of every tool; additional named, read-only secondaries are configured via the new MCPG_SECONDARY_DATABASE_URLS env var — comma- or newline-separated name=dsn entries, e.g. analytics=postgresql://…,reporting=postgresql://….

Every read-capable tool gains an optional database argument that selects a secondary by name; omitting it targets the primary. The new list_databases READ tool discovers every configured database id, which one is primary, each read_only flag, and a live SELECT 1 reachability probe.

Read-only is enforced by PostgreSQL, not by convention

Secondaries are read-only at the server level: every query against a secondary runs inside a BEGIN TRANSACTION READ ONLY, so a stray write fails closed with SQLSTATE 25006 even if the calling tool forgot to mark itself read-only. This is the design boundary that keeps the feature safe — it sidesteps per-database write/DDL/LISTEN gating entirely:

• Write / DDL / shell / listen / migrate tools always target the primary — they never carry the database argument.
• The global MCPG_ACCESS_MODE / MCPG_ALLOW_DDL / MCPG_ALLOW_SHELL / MCPG_ALLOW_LISTEN gates continue to apply to the primary exactly as before; secondaries simply can’t be written to.

Operational niceties: secondary DSNs get the same TLS enforcement as the primary; names must be simple identifiers ([a-z0-9_]+), unique, and not the reserved primary; and a secondary that fails to open at startup is marked unavailable (surfaced by list_databases) rather than aborting startup — mirroring the existing read-replica tolerance.

Also in this release: container images on GHCR

Pre-built images now publish to the GitHub Container Registry on every tagged release, so container users can pull instead of building from source:

docker pull ghcr.io/devopam/mcpg:0.6.5   # or :latest

The image build is the same production-grade multi-stage Dockerfile (non-root uid 10001, slim runtime). The push runs only after the maintainer-approved PyPI publish, so the container tracks the approved release.

Upgrade

pip install --upgrade mcpg   # once published to PyPI

No configuration changes required. Multi-database support is opt-in — leave MCPG_SECONDARY_DATABASE_URLS unset and the server behaves exactly as in 0.6.4.

Full changelog

See ../CHANGELOG.md [0.6.5] for the complete itemised list.