fix: pin postgres to version 17 to avoid data directory incompatibility

[FRosner]

Summary

Pins the postgres image to postgres:17 in docker-compose.yml. Postgres 18+ changed the default data directory structure, causing startup failures for users with existing volumes mounted at /var/lib/postgresql/data:

postgres-1  | Error: in 18+, these Docker images are configured to store database data in a
postgres-1  |        format which is compatible with "pg_ctlcluster" (specifically, using
postgres-1  |        major-version-specific directory names).  This better reflects how
postgres-1  |        PostgreSQL itself works, and how upgrades are to be performed.
postgres-1  |
postgres-1  |        See also https://github.com/docker-library/postgres/pull/1259
postgres-1  |
postgres-1  |        Counter to that, there appears to be PostgreSQL data in:
postgres-1  |          /var/lib/postgresql/data (unused mount/volume)
postgres-1  |
postgres-1  |        This is usually the result of upgrading the Docker image without
postgres-1  |        upgrading the underlying database using "pg_upgrade" (which requires both
postgres-1  |        versions).
postgres-1  |
postgres-1  |        The suggested container configuration for 18+ is to place a single mount
postgres-1  |        at /var/lib/postgresql which will then place PostgreSQL data in a
postgres-1  |        subdirectory, allowing usage of "pg_upgrade --link" without mount point
postgres-1  |        boundary issues.
postgres-1  |
postgres-1  |        See https://github.com/docker-library/postgres/issues/37 for a (long)
postgres-1  |        discussion around this process, and suggestions for how to do so.
postgres-1 exited with code 1

After pinning to 17 it works:

postgres-1  | The files belonging to this database system will be owned by user "postgres".
postgres-1  | This user must also own the server process.
postgres-1  |
postgres-1  | The database cluster will be initialized with locale "en_US.utf8".
postgres-1  | The default database encoding has accordingly been set to "UTF8".
postgres-1  | The default text search configuration will be set to "english".
postgres-1  |
postgres-1  | Data page checksums are disabled.
postgres-1  |
postgres-1  | fixing permissions on existing directory /var/lib/postgresql/data ... ok
postgres-1  | creating subdirectories ... ok
postgres-1  | selecting dynamic shared memory implementation ... posix
postgres-1  | selecting default "max_connections" ... 100
postgres-1  | selecting default "shared_buffers" ... 128MB
postgres-1  | selecting default time zone ... Etc/UTC
postgres-1  | creating configuration files ... ok
postgres-1  | running bootstrap script ... ok
postgres-1  | performing post-bootstrap initialization ... ok
postgres-1     | initdb: warning: enabling "trust" authentication for local connections
postgres-1     | initdb: hint: You can change this by editing pg_hba.conf or using the option -A, or --auth-local and --auth-host, the next time you run initdb.
postgres-1     | syncing data to disk ... ok
postgres-1     |
postgres-1     |
postgres-1     | Success. You can now start the database server using:
postgres-1     |
postgres-1     |     pg_ctl -D /var/lib/postgresql/data -l logfile start
postgres-1     |
postgres-1     | waiting for server to start....2026-03-05 14:29:38.814 UTC [48] LOG:  starting PostgreSQL 17.9 (Debian 17.9-1.pgdg13+1) on aarch64-unknown-linux-gnu, compiled by gcc (Debian 14.2.0-19) 14.2.0, 64-bit
postgres-1     | 2026-03-05 14:29:38.814 UTC [48] LOG:  listening on Unix socket "/var/run/postgresql/.s.PGSQL.5432"
postgres-1     | 2026-03-05 14:29:38.816 UTC [51] LOG:  database system was shut down at 2026-03-05 14:29:38 UTC
postgres-1     | 2026-03-05 14:29:38.818 UTC [48] LOG:  database system is ready to accept connections
postgres-1     |  done
postgres-1     | server started
postgres-1     |
postgres-1     | /usr/local/bin/docker-entrypoint.sh: ignoring /docker-entrypoint-initdb.d/*
postgres-1     |
postgres-1     | waiting for server to shut down...2026-03-05 14:29:38.929 UTC [48] LOG:  received fast shutdown request
postgres-1     | .2026-03-05 14:29:38.931 UTC [48] LOG:  aborting any active transactions
postgres-1     | 2026-03-05 14:29:38.931 UTC [48] LOG:  background worker "logical replication launcher" (PID 54) exited with exit code 1
postgres-1     | 2026-03-05 14:29:38.932 UTC [49] LOG:  shutting down
postgres-1     | 2026-03-05 14:29:38.932 UTC [49] LOG:  checkpoint starting: shutdown immediate
postgres-1     | 2026-03-05 14:29:38.934 UTC [49] LOG:  checkpoint complete: wrote 3 buffers (0.0%); 0 WAL file(s) added, 0 removed, 0 recycled; write=0.001 s, sync=0.001 s, total=0.003 s; sync files=2, longest=0.001 s, average=0.001 s; distance=0 kB, estimate=0 kB; lsn=0/14ED7C8, redo lsn=0/14ED7C8
postgres-1     | 2026-03-05 14:29:38.935 UTC [48] LOG:  database system is shut down
postgres-1     |  done
postgres-1     | server stopped
postgres-1     |
postgres-1     | PostgreSQL init process complete; ready for start up.
postgres-1     |
postgres-1     | 2026-03-05 14:29:39.047 UTC [1] LOG:  starting PostgreSQL 17.9 (Debian 17.9-1.pgdg13+1) on aarch64-unknown-linux-gnu, compiled by gcc (Debian 14.2.0-19) 14.2.0, 64-bit
postgres-1     | 2026-03-05 14:29:39.048 UTC [1] LOG:  listening on IPv4 address "0.0.0.0", port 5432
postgres-1     | 2026-03-05 14:29:39.048 UTC [1] LOG:  listening on IPv6 address "::", port 5432
postgres-1     | 2026-03-05 14:29:39.049 UTC [1] LOG:  listening on Unix socket "/var/run/postgresql/.s.PGSQL.5432"
postgres-1     | 2026-03-05 14:29:39.050 UTC [62] LOG:  database system was shut down at 2026-03-05 14:29:38 UTC
postgres-1     | 2026-03-05 14:29:39.052 UTC [1] LOG:  database system is ready to accept connections
postgres-1     | 2026-03-05 14:29:41.981 UTC [66] ERROR:  relation "schema_migrations" does not exist at character 27
postgres-1     | 2026-03-05 14:29:41.981 UTC [66] STATEMENT:  SELECT NULL AS "nil" FROM "schema_migrations" LIMIT 1
postgres-1     | 2026-03-05 14:29:41.983 UTC [66] ERROR:  relation "schema_info" does not exist at character 27
postgres-1     | 2026-03-05 14:29:41.983 UTC [66] STATEMENT:  SELECT NULL AS "nil" FROM "schema_info" LIMIT 1

🤖 Generated with Claude Code

[FRosner]

@YOU54F can you take a look please? :)

[YOU54F]

Thanks @FRosner