Installing PostgreSQL within a docker container - docker

Question

I've been following several different tutorials as well as the official one however whenever I try to install PostgreSQL within a container I get the following message afterwards
psql: 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"?
I've looked through several questions here on SO and throughout the internet but no luck.

Answer 1

The problem is that the your application/project is trying to access the postgres socket file in the HOST machine (not docker container).
To solve it one would either have to explicitly ask for an tcp/ip connection while using the -p flag to set up a port for the postgres container, or share the unix socket with the HOST maching using the -v flag.
:NOTE:
Using the -v or --volume= flag means you are sharing some space between the HOST machine and the docker container. That means that if you have postgres installed on your host machine and its running you will probably run into issues.
Below I demonstrate how to run a postgres container that is both accessible from tcp/ip and unix socket. Also I am naming the container as postgres.
docker run -p 5432:5432 -v /var/run/postgresql:/var/run/postgresql -d --name postgres postgres
There are other solutions, but I find this one the most suitable. Finally if the application/project that needs access is also a container, it is better to just link them.

Answer 2

By default psql is trying to connect to server using UNIX socket. That's why we see /var/run/postgresql/.s.PGSQL.5432- a location of UNIX-socket descriptor.
If you run postgresql-server in docker with port binding so you have to tell psql to use TCP-socket. Just add host param (--host or -h):
psql -h localhost [any other params]
UPD. Or share UNIX socket descriptor with host (where psql will be started) as was shown in main answer. But I prefer to use TCP socket as easy managed approach.

Answer 3

FROM postgres:9.6
RUN apt-get update && apt-get install -q -y postgresql-9.6 postgresql-client-9.6 postgresql-contrib-9.6 postgresql-client-common postgresql-common
RUN echo postgres:postgres | chpasswd
RUN pg_createcluster 9.6 main --start
RUN /etc/init.d/postgresql start
RUN su -c "psql -c \"ALTER USER postgres PASSWORD 'postgres';\"" postgres

Answer 4

Here are instructions for fixing that error that should also work for your docker container: PostgreSQL error 'Could not connect to server: No such file or directory'
If that doesn't work for any reason, there are many of off-the-shelf postgresql docker containers you can look at for reference on the Docker Index: https://index.docker.io/search?q=postgresql
Many of the containers are built from trusted repos on github. So if you find one that seems like it meets your needs, you can review the source.
The Flynn project has also included a postgresql appliance that might be worth checking out: https://github.com/flynn/flynn-postgres

Answer 5

Run the below command to create a new container with PSQL running it it, which can be accessed from other containers/applications.
docker run --name postgresql-container -p 5432:5432 -e POSTGRES_PASSWORD=somePassword -d postgres
Now, export the connection-string or DB credentials from ur .env and use it in the application.
Refernce: detailed installion and running