Builds public, multi-arch Docker images of pgquarrel with an ENTRYPOINT so the image is callable like a command. Used by DockerPgquarrel in ktts-webapp-sample's database-lib to diff PostgreSQL schemas across environments.

One sub-directory per PostgreSQL base version:

16.9/Dockerfile   16.9/push.sh
18.0/Dockerfile   18.0/push.sh

Each version produces its own image tag. Multiple versions coexist because pgquarrel is bound at compile time to the PG headers it was built against: the postgresql-server-dev-NN package determines which server versions the resulting binary can talk to (see Version coupling below).

mlorber/public:pgquarrel-compare-<pgquarrel-ref>-pg<pg-version>

• <pgquarrel-ref> — either a short SHA of a master commit (e.g. 80637e4) or a release tag in slug form (e.g. 0_7_0).
• <pg-version> — the postgres:NN.M base image tag (e.g. 18.0).

Examples produced by this repo:

Production code (DockerPgquarrel.image in ktts-webapp-sample) always pins to one of these immutable tags.

• PG14+ base → use a master commit. The pgquarrel_0_7_0 release (March 2023) calls simple_prompt(prompt, buf, len, echo) (4 args), but PG14 changed the signature to simple_prompt(prompt, echo) (2 args). Master gates the call with #if PG_VERSION_NUM >= 140000 and compiles cleanly on PG14 through PG18.
• PG13 and earlier → either master or the pgquarrel_0_7_0 tag work; the tag is preferable when you want an immutable release as the source of truth.

Pin to a specific SHA either way so the build is reproducible.

Two pitfalls aligned, both fixed by the same rule: the postgresql-server-dev-NN you install at build time must match the postgres:NN.M base:

1. postgresql-server-dev-all (a meta package) makes pg_config resolve to whichever pg-dev was installed last by apt. The Debian repos started shipping pg18-dev recently, which silently changes the build. Pin postgresql-server-dev-NN explicitly.

2. pgquarrel checks the server version at connect time and refuses to talk to a server newer than the PG version it was compiled against:

   cannot connect to server whose version (X.Y) is greater than postgres version (Z.W) used to compile pgquarrel

   So a pg18.0 image can connect to PG ≤ 18; a pg16.9 image can connect to PG ≤ 16. Pick the image that covers the newest server you need to diff.

The image must be a multi-arch manifest — it's consumed both on Apple Silicon dev machines (arm64) and on CI/Linux servers (amd64).

# One-time
docker login
docker buildx create --use --name multiarch

# Build & push a version (the context is the subdir)
cd 18.0
./push.sh

push.sh in each subdir is hardcoded for that version's image tag. To bump a version in place, edit Dockerfile and push.sh together and re-run.

1. cp -r 18.0 NEW_VERSION (e.g. 19.0).
2. In NEW_VERSION/Dockerfile:
   • Update FROM postgres:NEW_VERSION.
   • Update postgresql-server-dev-NN (and the matching apt-get purge line).
   • Pick the pgquarrel ref per Which pgquarrel ref to pick.
3. In NEW_VERSION/push.sh, update the image tag (-pgNEW_VERSION suffix and the pgquarrel ref slug).
4. cd NEW_VERSION && ./push.sh.
5. Update DockerPgquarrel.image in ktts-webapp-sample to point at the new immutable tag.