Unable to run psql command inside a postgres docker container - bash

Question

I have recently started using Docker. However, while I was able to run a postgres container and run a bash command "psql" inside it. Now, I am facing error in trying to do the same after sometime.
Here is what worked for me sometime back and now it does not work anymore:
docker run --rm -it postgres bash
The above command opens a bash inside the postgres container. When I type psql inside this container, it shows error:
root#3615146cf679:/# psql
psql: error: could not connect to server: could not connect to server: No such file or directory
Is the server running locally and accepting
connections on Unix domain socket “/var/run/postgresql/.s.PGSQL.5432”?

Answer 1

You need to use these commands in order:
start the container with:
$ sudo docker run --name some-postgres -e POSTGRES_PASSWORD=mysecretpassword -d postgres
enter the container with:
$ sudo docker exec -it some-postgres /bin/bash
when you entered the container, run:
$ psql -U postgres

Answer 2

I myself figured it out that using "bash" at the time of starting the container was causing the problem. Once we run it using:
docker run --rm postgres
Above command says that we need to provide a Password or Auth Method. Hence, we do so.
Anyone of below 3 commands can start a postgres container:
docker run --rm -e POSTGRES_PASSWORD=postgres postgres
or
docker run --rm -e POSTGRES_HOST_AUTH_METHOD=trust postgres
or
docker run --rm -e POSTGRES_HOST_AUTH_METHOD=trust -e POSTGRES_USER=postgres -e
POSTGRES_PASSWORD=postgres postgres
Then, we can execute:
docker exec -it <container_id> bash
psql -U postgres
CREATE TABLE tutorials (id int, tutorial_name text);
INSERT INTO tutorials VALUES (1, 'C++');
select * from tutorials;