Make sure postgres is ready to accept connections before neon-proxy starts

[krachtstefan]

I found an issue where it is possible to have both containers running without the neon_control_plane schema being created. It's a race condition that is very likely to happen when running docker compose up for the first time.

how to reproduce

• to be on a clean slate, run docker compose down --volumes to remove the containers and get rid of the db volume
• run docker-compose up to start everything
• neon-proxy-1 was not able to create the schema. The logs show that the DB was not initialized at this point even though the Postgres service was started.

...
postgres-1    | creating configuration files ... ok
neon-proxy-1  | psql: error: connection to server at "postgres" (192.168.96.2), port 5432 failed: Connection refused
neon-proxy-1  | 	Is the server running on that host and accepting TCP/IP connections?
...
postgres-1    | PostgreSQL init process complete; ready for start up.
...

• both containers are running now, but the DB has no neon_control_plane schema
• press CTRL+C to stop the containers
• run docker-compose up to start the containers again
• this time the DB inits faster and it is very likely that the schema will be created

solution

Instead of only waiting for Postgres container to be running, ChatGPT I added a health check that can be used in the depends_on block of the neon-proxy service to guarantee that the DB can be used already.

Now the logs indicate that the DB is used after its initialization.

postgres-1    | PostgreSQL init process complete; ready for start up.
...
neon-proxy-1  | CREATE SCHEMA
...
neon-proxy-1  | CREATE TABLE

[TimoWilhelm]

Thanks, good catch! I guess I got lucky with the startup so far.

[krachtstefan]

You’re welcome!