Docker not recognizing Postgresql data directory

Question

I am desperately trying to get a Docker project I have inherited up and running, and Docker is giving me no end of problems. When trying to start up my containers I get the following error on my Postgresql container:

FATAL:  "/var/lib/postgresql/data" is not a valid data directory
DETAIL:  File "/var/lib/postgresql/data/PG_VERSION" does not contain valid data.
HINT:  You might need to initdb.

The project is a Rails project using Redis, ElasticSearch, and Sidekiq containers as well - those all load fine.

docker-compose.yml:

postgres:
  image: postgres:9.6.2
  environment:
    POSTGRES_USER: $PG_USER
    POSTGRES_PASSWORD: $PG_PASS
  ports:
    - '5432:5432'
  volumes:
    - postgres:/var/lib/postgresql/data

/var/lib/postgresql/data is owned by the postgres user (as it should be I believe) and the postgresql service starts up and runs fine on its own.

I have tried running initdb from the /usr/lib/postgresql/9.6/bin directory, as well as from docker (from docker it doesn't seem to persist or even create anything... if anyone knows why I would be interested in knowing)

The contents of the /var/lib/postgresql/data directory:

drwxrwxrwx 19 postgres postgres  4096 Jun 28 20:41 .
drwxr-xr-x  5 postgres postgres  4096 Jun 28 20:41 ..
drwx------  5 postgres postgres  4096 Jun 28 20:41 base
drwx------  2 postgres postgres  4096 Jun 28 20:41 global
drwx------  2 postgres postgres  4096 Jun 28 20:41 pg_clog
drwx------  2 postgres postgres  4096 Jun 28 20:41 pg_commit_ts
drwx------  2 postgres postgres  4096 Jun 28 20:41 pg_dynshmem
-rw-------  1 postgres postgres  4468 Jun 28 20:41 pg_hba.conf
-rw-------  1 postgres postgres  1636 Jun 28 20:41 pg_ident.conf
drwx------  4 postgres postgres  4096 Jun 28 20:41 pg_logical
drwx------  4 postgres postgres  4096 Jun 28 20:41 pg_multixact
drwx------  2 postgres postgres  4096 Jun 28 20:41 pg_notify
drwx------  2 postgres postgres  4096 Jun 28 20:41 pg_replslot
drwx------  2 postgres postgres  4096 Jun 28 20:41 pg_serial
drwx------  2 postgres postgres  4096 Jun 28 20:41 pg_snapshots
drwx------  2 postgres postgres  4096 Jun 28 20:41 pg_stat
drwx------  2 postgres postgres  4096 Jun 28 20:41 pg_stat_tmp
drwx------  2 postgres postgres  4096 Jun 28 20:41 pg_subtrans
drwx------  2 postgres postgres  4096 Jun 28 20:41 pg_tblspc
drwx------  2 postgres postgres  4096 Jun 28 20:41 pg_twophase
-rw-------  1 postgres postgres     4 Jun 28 20:41 PG_VERSION
drwx------  3 postgres postgres  4096 Jun 28 20:41 pg_xlog
-rw-------  1 postgres postgres    88 Jun 28 20:41 postgresql.auto.conf
-rw-------  1 postgres postgres 22267 Jun 28 20:41 postgresql.conf  

PG_VERSION contains 9.6

Any help is much appreciated.

Answer 1

you're changing default postgresql data path hence you need to initialize the database. try this

volumes:
    - ./init.sql:/docker-entrypoint-initdb.d/init.sql

here is the init.sql file

CREATE USER docker;
CREATE DATABASE docker;
GRANT ALL PRIVILEGES ON DATABASE docker TO docker;

Answer 2

I had the same issue, I restarted Docker daemon and even restarted the machine, but didn't fix the issue.
The path /var/lib/postgresql/data was not even on the FS.

Note: Performing a docker ps was not showing the postgresql container as running.

Solution (docker-compose):

• Close postgres container:
  docker-compose -f <path_to_my_docker_compose_file.yaml> down postgres

• Start postgres container:
  docker-compose -f <path_to_my_docker_compose_file.yaml> -d up postgres

-- That did the trick! --

Solution (docker):

docker stop <postgres_container>
docker start <postgres_container>

Another solution that you can try:
initdb <temporary_volum_folder>
Example:
initdb /tmp/postgres
docker-compose -f <path_to_my_docker_compose_file.yaml> -d up postgres
or
initdb /tmp/postgres docker start <postgres_container>

Note:
In my case the postgres image is defined in docker-compose.yaml file, and it can be observed I don't define PG_DAT nor PG_VERSION and the container runs ok.

  postgres:
    image: postgres:9.6.14
    container_name: postgres
    environment:
      POSTGRES_USER: 'pg12345678'
      POSTGRES_PASSWORD: 'pg12345678'
    ports:
      - "5432:5432"