Connect to postgres in docker container from host machine - postgresql

Question

How can I connect to postgres in docker from a host machine?
docker-compose.yml
version: '2'
networks:
database:
driver: bridge
services:
app:
build:
context: .
dockerfile: Application.Dockerfile
env_file:
- docker/Application/env_files/main.env
ports:
- "8060:80"
networks:
- database
depends_on:
- appdb
appdb:
image: postdock/postgres:1.9-postgres-extended95-repmgr32
environment:
POSTGRES_PASSWORD: app_pass
POSTGRES_USER: www-data
POSTGRES_DB: app_db
CLUSTER_NODE_NETWORK_NAME: appdb
NODE_ID: 1
NODE_NAME: node1
ports:
- "5432:5432"
networks:
database:
aliases:
- database
docker-compose ps
Name Command State Ports
-----------------------------------------------------------------------------------------------------
appname_app_1 /bin/sh -c /app/start.sh Up 0.0.0.0:8060->80/tcp
appname_appdb_1 docker-entrypoint.sh /usr/ ... Up 22/tcp, 0.0.0.0:5432->5432/tcp
From container I can connect successfully. Both from app container and db container.
List of dbs and users from running psql inside container:
# psql -U postgres
psql (9.5.13)
Type "help" for help.
postgres=# \du
List of roles
Role name | Attributes | Member of
------------------+------------------------------------------------------------+-----------
postgres | Superuser, Create role, Create DB, Replication, Bypass RLS | {}
replication_user | Superuser, Create role, Create DB, Replication | {}
www-data | Superuser | {}
postgres=# \l
List of databases
Name | Owner | Encoding | Collate | Ctype | Access privileges
----------------+------------------+----------+------------+------------+-----------------------
app_db | postgres | UTF8 | en_US.utf8 | en_US.utf8 |
postgres | postgres | UTF8 | en_US.utf8 | en_US.utf8 |
replication_db | replication_user | UTF8 | en_US.utf8 | en_US.utf8 |
template0 | postgres | UTF8 | en_US.utf8 | en_US.utf8 | =c/postgres +
| | | | | postgres=CTc/postgres
template1 | postgres | UTF8 | en_US.utf8 | en_US.utf8 | =c/postgres +
| | | | | postgres=CTc/postgres
(5 rows)
DB image is not official postgres image. But Dockerfile in GitHub seem looking fine.
cat /var/lib/postgresql/data/pg_hba.conf from DB container:
# TYPE DATABASE USER ADDRESS METHOD
# "local" is for Unix domain socket connections only
local all all trust
# IPv4 local connections:
host all all 127.0.0.1/32 trust
# IPv6 local connections:
host all all ::1/128 trust
# Allow replication connections from localhost, by a user with the
# replication privilege.
#local replication postgres trust
#host replication postgres 127.0.0.1/32 trust
#host replication postgres ::1/128 trust
host all all all md5
host replication replication_user 0.0.0.0/0 md5
I tried both users with no luck
$ psql -U postgres -h localhost
psql: FATAL: role "postgres" does not exist
$ psql -h localhost -U www-data appdb -W
Password for user www-data:
psql: FATAL: role "www-data" does not exist
Looks like on my host machine there is already PSQL running on that port. How can I check it?

Answer 1

I believe the problem is you have postgres running on the local machine at port 5432.
Issue can be resolved by mapping port 5432 of docker container to another port in the host machine.
This can be achieved by making a change in docker-compose.yml
Change
"5432:5432"
to
"5433:5432"
Restart docker-compose
Now the docker container postgres is running on 5433. (Locally installed postgres is on 5432)
You can try connecting to the docker container.
psql -p 5433 -d db_name -U user -h localhost

Answer 2

I ran this on Ubuntu 16.04
$ psql -h localhost -U www-data app_db
Password for user www-data:
psql (9.5.13)
Type "help" for help.
app_db=# \du
List of roles
Role name | Attributes | Member of
------------------+------------------------------------------------------------+-----------
postgres | Superuser, Create role, Create DB, Replication, Bypass RLS | {}
replication_user | Superuser, Create role, Create DB, Replication | {}
www-data | Superuser | {}
And below from my mac to the VM inside which docker was running (192.168.33.100 is the IP address of the docker VM)
$ psql -h 192.168.33.100 -U www-data app_db
Password for user www-data:
psql (9.6.9, server 9.5.13)
Type "help" for help.
app_db=# \du
List of roles
Role name | Attributes | Member of
------------------+------------------------------------------------------------+-----------
postgres | Superuser, Create role, Create DB, Replication, Bypass RLS | {}
replication_user | Superuser, Create role, Create DB, Replication | {}
www-data | Superuser | {}
They both work for me.
PSQL version on VM
$ psql --version
psql (PostgreSQL) 9.5.13
PSQL version on Mac
$ psql --version
psql (PostgreSQL) 9.6.9

Answer 3

I had the same problem on elementary OS 5.0 while running postgres 10 official docker container though. I was able to connect from host using the ip of the running container.
sudo docker inspect -f '{{range .NetworkSettings.Networks}}{{.IPAddress}}{{end}}' container_name/id
Test after getting the ip:
psql -h 172.17.0.2 -U postgres

Answer 4

I believe you have an issue in pg_hba.conf. Here you've specified 1 host that has access - 127.0.0.1/32.
You can change it to this:
# IPv4 local connections:
host all all 0.0.0.0/0 md5
This will make sure your host (totally different IP) can connect.
To check if there is an instance of postgresql already running, you can do
netstat -plnt | grep 5432. If you get any result from this you can get the PID and verify the process itself.

Answer 5

I have a relatively similar setup, and the following works for me to open a psql session on the host machine into the docker postgres instance:
docker-compose run --rm db psql -h db -U postgres -d app_development
Where:
db is the name of the container
postgres is the name of the user
app_development is the name of the database
So for you, it would look like docker-compose run --rm appdb psql -h appdb -U www-data -d app_db.

Answer 6

Since you’re running it in OSX, you can always use the pre-installed Network Utility app to run a Port Scan on your host and identify if the postgres server is running (and if yes, on which port).
But I don’t think you have one running on your host. The problem is that Postgres by default runs on 5432 and the docker-compose file that you are trying to run exposes the db container on the same port i.e. 5432. If the Postgres server were already running on your host, then Docker would have tried to expose a a container to a port which is already being used, thereby giving an error.
Another potential solution:
As can be seen in this answer, mysql opens a unix socket with localhost and not a tcp socket. Maybe something similar is happening here.
Try using 127.0.0.1 instead of localhost while connecting to the server in the container.