Why postgres container changes folder`s owner (docker-compose)

Question

My docker-compose.yml is

  database:
    container_name: k4fntr_database
    build: ./docker/postgres
    restart: always
    environment:
      ENV: ${APP_ENV}
      TESTING_DB: ${DB_DATABASE_TESTING}
      POSTGRES_DB: ${DB_DATABASE}
      POSTGRES_USER: ${DB_USERNAME}
      POSTGRES_PASSWORD: ${DB_PASSWORD}
    ports:
      - "15432:5432"
    volumes:
    - ./docker/postgres/pg-data:/var/lib/postgresql/data
    networks:
      - backend-network

and my Dockerfile is

FROM postgres:10.5-alpine

COPY /docker-entrypoint-initdb.d/ /docker-entrypoint-initdb.d/

RUN chmod 0755 -R /docker-entrypoint-initdb.d/

I have a problem when I run

docker-compose up -d --build

a folder which is called pg-data is created with wrong permissions from user "70" and group "root"

This permissions don't let me to do any things such as look inside the folder. In addition, when I try to rebuild the container with

docker-compose up -d --build

I get an error

PermissionError: [Errno 13] Permission denied: '/home/ubuntu/PhpstormProjects/fntr/docker/postgres/pg-data' [5262] Failed to execute script docker-compose

I run docker-compose as user ubuntu:ubuntu.

The situation was changed a little bit when I created folder BEFORE run

docker-compose up -d --build

In this case the folder has group "ubuntu" but the owner is still "70"

but there is no some effects and all problems are exists

Please add Dockerfile for the image. Most likely, the container is running as user 70 and is creating a folder using this. Inside the container, user 70 is resolvable through /etc/passwd but it is not resolvable on the host machine. — Palash Goel
– Palash Goel, Commented Feb 27, 2020 at 12:08
I have dockerfile but there aren`t some interesting things FROM postgres:10.5-alpine COPY /docker-entrypoint-initdb.d/ /docker-entrypoint-initdb.d/ — Viktor
– Viktor, Commented Feb 27, 2020 at 12:16

Palash Goel · Accepted Answer · 2020-02-27 13:50:15Z

2

Postgres run an entrypoint file when a container is started.

https://github.com/docker-library/postgres/blob/master/10/docker-entrypoint.sh#L36

This is the function that changes the permission of the directory inside docker container. Since this directory is mounted on the host file-system too, the permissions are reflected there.

On your system, check the user currently mapped to uid-999. You can have a clue from there. Avoid posting /etc/passwd or /etc/shadow file here

You need to pass User in docker-compose

See https://hub.docker.com/_/postgres -> Arbitrary --user Notes

edited Feb 27, 2020 at 13:50

answered Feb 27, 2020 at 12:25

Palash Goel

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2 Comments

Viktor Over a year ago

cat /etc/passwd | grep 999 guest-sdklnd:x:999:999:Guest:/tmp/guest-sdklnd:/bin/bash

Viktor Over a year ago

I can't understand. Postgres doing that inside the container, but I have problem with my filesystem

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