pgsync

A deliberately boring tool.

Copying a database between two Postgres instances is easy to get wrong in a hurry: dump flags, ON_ERROR_STOP, and whether logs contaminate the dump stream.

The problem did not need a service, a framework, or a container.

Why a Bash script?

PostgreSQL already provides the primitive:

pg_dump | psql

pgsync wraps that primitive with safer defaults, URI source/target, bash completion, and a few flags people already know from rsync.

The interesting decision was knowing what not to build. There is no incremental mode. This is always a full logical dump/restore.

The pipe is the interface

All status goes to stderr. stdout is reserved for the dump. A dry-run prints the quoted pipeline and exits.

psql runs with ON_ERROR_STOP=1. Unless --no-clean, dump uses --clean --if-exists. Every dump uses --no-owner --no-privileges so restores do not drag source roles onto the target.

--delete is a separate, explicit pre-step: DROP SCHEMA public CASCADE then CREATE SCHEMA public.

rsync-shaped CLI

Flag	Behavior
-n	Print the pipeline; do not run it
--delete	Recreate public on the target first
-q / -v	Quiet / show the exact command
--schema-only / --data-only	Narrow the dump

Completion lives in completions/pgsync.bash and does not require bash-completion.deb. install.sh places the binary and the completion file under a configurable prefix.

Docker and GHCR

The same script runs in a container built on postgres:16-bookworm, so callers do not need local pg_dump / psql:

docker run --rm ghcr.io/mamahoos/pgsync:latest \
  -s 'postgresql://user:pass@source:5432/dbname' \
  -t 'postgresql://user:pass@target:5432/dbname'

Every version tag publishes to GHCR with semver and latest. docker-compose.yml runs a two-Postgres smoke test — the same stack the publish workflow exercises before push.

CI

GitHub Actions splits concerns instead of one catch-all job:

Workflow	Trigger	What it proves
test.yml	push / PR	ShellCheck on the scripts, Bats unit tests, then integration sync against two Postgres 16 services
docker-publish.yml	version tag	image build, compose smoke test, push to GHCR

Integration tests use real URIs and assert quiet mode, data-only restores, and the full dump/restore path. The Docker publish job only runs after the image passes the same compose sync the README documents.

What this demonstrates

Operational restraint: a one-shot, auditable script with Unix I/O discipline, instead of a platform around a two-command pipeline — plus just enough packaging and CI to trust it in other workflows.