PostgreSQL and pgAdmin both running in Docker containers and connecting - postgresql

Question

I am attempting to run both PostgreSQL and pgAdmin in Docker containers. The idea is that the PostgreSQL database should be accessible to any applications I have running on the host machine, and also to pgAdmin.
I am using this command to run PostgreSQL:
docker run -d -e POSTGRES_USER=username -e POSTGRES_PASSWORD=password --name postgres -p 5432:5432 postgres
And to run pgAdmin:
docker run -d -p 1111:1111 --name pgadmin -e "PGADMIN_LISTEN_PORT=1111" -e "PGADMIN_DEFAULT_EMAIL=admin#test.com" -e "PGADMIN_DEFAULT_PASSWORD=test" dpage/pgadmin4
If I go to localhost:1111, I can connect to pgAdmin and login. However, when I try to connect to my local PostgreSQL instance, it gets no response.
Therefore, I tried to run pgAdmin with access to the host internet using --net=host instead of -p 1111:1111:
docker run -d --net=host --name pgadmin -e "PGADMIN_LISTEN_PORT=1111" -e "PGADMIN_DEFAULT_EMAIL=admin#test.com" -e "PGADMIN_DEFAULT_PASSWORD=test" dpage/pgadmin4
Now, when I try to go to localhost:1111 to connect to pgAdmin, I get no response in my browser.
Docker Compose is a possible solution, as I could link the two containers together so they could access each other without having to worry about ports, but I also need pgAdmin to be able to access PostgreSQL instances on other machines, as well as my local one.
I feel like --net=host is broken in Docker. There's a whole thread here with a lot of confusion.
My setup:
Host: Windows 10
Docker: Docker Desktop Community v2.0.0.3 (31259)
Update
I have now tried using --link postgres on the pgAdmin container and it allows me to connect to my local instance of PostgreSQL but not non-local ones, the full command is:
docker run -d -p 1111:1111 --link postgres --name pgadmin -e "PGADMIN_LISTEN_PORT=1111" -e "PGADMIN_DEFAULT_EMAIL=admin#test.com" -e "PGADMIN_DEFAULT_PASSWORD=test" dpage/pgadmin4

Answer 1

The commands were not wrong, only the connection in pgAdmin, so the full list of commands are:
For PostgreSQL:
docker run -d -e POSTGRES_USER=username -e POSTGRES_PASSWORD=password --name postgres -p 5432:5432 postgres
And pgAdmin:
docker run -d -p 1111:1111 --name pgadmin -e "PGADMIN_LISTEN_PORT=1111" -e "PGADMIN_DEFAULT_EMAIL=admin#test.com" -e "PGADMIN_DEFAULT_PASSWORD=test" dpage/pgadmin4
Now the pgAdmin container won't connect to localhost but needs the IP of the PostgreSQL container. Run:
docker inspect postgres
Inspect result:
[
{
...
"NetworkSettings": {
...
"Networks": {
...
"IPAddress": "172.17.0.3",
...
}
}
}
]
We're only interested in the IPAddress from the inspect command. This is the IP which pgAdmin should connect to.
pgAdmin is also capable of access external IPs from your machine.

Answer 2

When you create docker containers it creates a bridge network. First find the network range for the bridge network. You can use ifconfig to find it. Let's say 172.17.0.5 is ip of pgAdmin, Then create a user 'root'#'172.17.0.5' for PostgreSQL and give database permissions for that user. Then you can connect to the database. Also check if port 3306 is accessible using telnet.