Invoke dbmate from Docker and trigger migration in postgres

[jayarjo]

I was trying the following:

$ docker run --rm -it --env DATABASE_URL="..." --mount type=bind,source=...,target=/app amacneil/dbmate --no-dump-schema --migrations-dir /app up

However I repeatedly get:

Error: dial tcp 127.0.0.1:57806: connect: connection refused

DATABASE_URL points to the postgres server running on another Docker container (not sure how that should matter?)

Do I need to to anything in addition to the above command to be able to run migrations on another Docker container that is running postgres?

[jayarjo]

In fact forget about another Docker container, it fails to connect to the postgres on the host as well, with the same error.

[amacneil]

By default docker containers have their own network and IP address. There are several ways you can work around this.

If you're running postgres on your local computer you should be able to connect to it by running the dbmate container with host networking (I'll add this to the readme):

docker run --rm --network=host -it amacneil/dbmate

If you're running postgres in another container, again there are several ways to solve this. One option is to expose the port from the postgres container to your host (using -p flag), then use host networking (as above) when running dbmate to connect via localhost:

docker run --rm -d -p 5432:5432 -e POSTGRES_PASSWORD=postgres postgres
docker run --rm -it --network=host -e DATABASE_URL="postgres://postgres:postgres@localhost/foo?sslmode=disable" amacneil/dbmate create

Another is to put both the postgres container and dbmate on a private container network (and not expose them to the host):

docker network create mynet
docker run --rm -d -e POSTGRES_PASSWORD=postgres --name=pg --network=mynet postgres
docker run --rm --network=mynet -e DATABASE_URL="postgres://postgres:postgres@pg/foo?sslmode=disable" amacneil/dbmate create

Finally, you can also do this using docker compose by adding depends_on, which is what we do for dbmate development & testing.

[jayarjo]

@amacneil thanks for taking your time to clarify this. Would have been great to have this somewhere in readme.

[amacneil]

Thanks for the feedback - I updated the readme.