fireproofsocks
Dumb question and one I used to know the answer to… but how does one connect to a postgres instance running inside docker-compose? I thought I would work through Broadway’s example repo GitHub - elixir-broadway/broadway_bike_sharing_rabbitmq_example: An example of a Broadway pipeline for a bike sharing app with RabbitMQ and PostgreSQL · GitHub – it uses docker-compose to spin up both a version of Postgres (one specifically with postgis installed) and an instance of RabbitMQ.
docker-compose up seems to have worked… no errors, and Docker Desktop shows 3 containers: rabbitmq-1, db-1, and app-1. RabbitMQ and Postgres are running, but the app has crashed because it can’t connect to the database.
Looking more closely, it seems like the port directive in docker-compose.yml is being ignored. I’ve deleted the images and rebuilt this several times in the course of testing it, and each time the ports used come up with something more random (?) like 53665. If I set my database client to use that port, I can connect.
Can someone clarify why this port is changing? And I seem to remember that the list of services defined inside of the docker-compose.yml corresponded to hostnames? Is that accurate? Like, instead of localhost, you might reference a hostname of db – but that doesn’t seem to work (even if I use the numeric extension).
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dimitarvp
Again, very likely it’s because their
docker-compose.yamlfile is used for CI/CD and deployment, not for local development, that’s my hypothesis. If it was used for local dev then surely it would have the host:container port pairs.D4no0
Yes, you can reference containers by their service names, no numeric extension should be added, the name should be exactly as it is defined in
docker-compose.yml.portoption is for just exposing the container port to your host, the optionport: "5432"will expose port 5432 from the container on your host on 5432.I would recommend checking that your host 5432 port is free, otherwise map to a different port:
Also ensure that you are not connecting to some already exsting volumes with some strange Postgres configurations, a clean postgres/postgis container will always serve on port 5432 by default.
The last and the first thing I should have mentioned is to check that the database container has started as expected, it can happen that it will not start if it’s missing some mandatory configuration options (like username), you should have logs that it started accepting clients on port 5432.
D4no0
I’ve just ran the
docker-composeand everything works as expected from the standpoint of database. It’s a very strange setup, but it works as expected without any issues.What OS are you using? I’ve ran the example on ubuntu.
The only thing to keep in mind is that ecto migrations are not ran automatically, so you have to execute this command before starting the compose: