从另一个容器访问 Docker postgres 容器

Question

I am trying to make a portable solution to having my application container connect to a postgres container. By 'portable' I mean that I can give the user two docker run commands, one for each container, and they will always work together.

I have a postgres docker container running on my local PC, and I run it like this,

docker run -p 5432:5432 -v $(pwd)/datadir:/var/lib/postgresql/data -e POSTGRES_PASSWORD=qwerty -d postgres:11

and I am able to access it from a python flask app, using the address 127.0.0.1:5432 .

I put the python app in a docker container as well, and I am having trouble connecting to the postgres container.

Address 127.0.0.1:5432 does not work.

Address 172.17.0.2:5432 DOES work (172.17.0.2 is the address of the docker container running postgres). However I consider this not portable because I can't guarantee what the postgres container IP will be.

I am aware of the --add-host flag, but it is also asking for the host-ip, which I want to be the localhost (127.0.0.1). Despite several hits on --add-host I wasn't able to get that to work so that the final docker run commands can be the same on any computer they are run on.

I also tried this: docker container port accessed from another container

My situation is that the postgres and myApp will be containers running on the same computer. I would prefer a non-Docker compose solution.

Answer 1

The comment from Truong had me try that approach (again) and I got it working. Here are my steps in case it helps out another. The crux of the problem was needing one container to address another container in a way that was static (didn't change). Using user defined network was the answer, because you can name a container, and thus reference that container IP by that name.

My steps,

docker network create mynet
docker run --net mynet --name mydb -v $(pwd)/datadir:/var/lib/postgresql/data -e POSTGRES_PASSWORD=qwerty -d postgres:11

Now the IP address of the postgres database is mydb , and all the ports of this container are exposed to any other container running in this network.

Now add the front end app,

docker run --net mynet -ti -p 80:80 -v mydockerhubaccount/myapp