Docker Compose，如何去除bind mount数据？

Question

I'm creating a PostgreSQL database with Docker Compose on Debian 11.

• Docker version 20.10.14, build a224086
• Docker Compose version v2.3.3

When I try to shutdown Docker Compose and remove all existing data, I cannot seem to get rid of bind mounted data.

docker-compose.yml

version: '3'

services:
  postgres:
    image: postgres:9.3.25
    healthcheck:
      test: [ "CMD", "pg_isready", "-q", "-d", "postgres", "-U", "root" ]
      timeout: 45s
      interval: 10s
      retries: 10
    restart: always
    environment:
      - POSTGRES_USER=root
      - POSTGRES_PASSWORD=docker
      - APP_DB_USER=app_user
      - APP_DB_PASS=docker
      - APP_DB_NAME=myapp_db
    # Notice this creates bind mounts, not volumes!
    volumes:
      - ./db-entry-point:/docker-entrypoint-initdb.d/
      - ./postgres-db-data:/var/lib/postgresql/data
    ports:
      - 5432:5432

The command below is issued to shutdown docker containers. I know it doesn't remove volumes by default. --volumes argument could be used for removing volumes, but I tested that it doesn't remove bind mound data.

docker compose -f /opt/storage/disk-03/docker/myapp-db/docker-compose.yml down

These files are on the bind mount target directory:

ls -la /opt/storage/disk-03/docker/myapp-db/postgres-db-data/
total 44
drwx------ 15 systemd-timesync root               329 Mar 29 09:52 .
drwxr-xr-x  4 root             root                78 Mar 29 09:35 ..
-rw-------  1 systemd-timesync systemd-timesync     4 Mar 28 14:52 PG_VERSION
drwx------  7 systemd-timesync systemd-timesync    67 Mar 28 14:52 base
drwx------  2 systemd-timesync systemd-timesync  4096 Mar 29 09:51 global
drwx------  2 systemd-timesync systemd-timesync    18 Mar 28 14:52 pg_clog
-rw-------  1 systemd-timesync systemd-timesync  4486 Mar 28 14:52 pg_hba.conf
-rw-------  1 systemd-timesync systemd-timesync  1636 Mar 28 14:52 pg_ident.conf
drwx------  4 systemd-timesync systemd-timesync    36 Mar 28 14:52 pg_multixact
drwx------  2 systemd-timesync systemd-timesync    18 Mar 29 09:50 pg_notify
drwx------  2 systemd-timesync systemd-timesync     6 Mar 28 14:52 pg_serial
drwx------  2 systemd-timesync systemd-timesync     6 Mar 28 14:52 pg_snapshots
drwx------  2 systemd-timesync systemd-timesync   105 Mar 29 09:52 pg_stat
drwx------  2 systemd-timesync systemd-timesync     6 Mar 29 09:52 pg_stat_tmp
drwx------  2 systemd-timesync systemd-timesync    18 Mar 28 14:52 pg_subtrans
drwx------  2 systemd-timesync systemd-timesync     6 Mar 28 14:52 pg_tblspc
drwx------  2 systemd-timesync systemd-timesync     6 Mar 28 14:52 pg_twophase
drwx------  3 systemd-timesync systemd-timesync    60 Mar 28 14:52 pg_xlog
-rw-------  1 systemd-timesync systemd-timesync 20120 Mar 28 14:52 postgresql.conf
-rw-------  1 systemd-timesync systemd-timesync    37 Mar 29 09:50 postmaster.opts

I'm not sure how to delete these files as rm -rf doesn't remove them. ls -la /opt/storage/disk-03/docker/myapp-db/postgres-db-data/ still lists the files.

sudo rm -rf /opt/storage/disk-03/docker/myapp-db/postgres-db-data/*

What would be the right way from Docker's perspective to remove these files?

Answer 1

Seems that the files can be removed by changing the owner of the files first and then removing. I'm not sure what's going on in the underlying OS, but I tested this couple times and it works.

# This doesn't remove the files when files are owned by "systemd-timesync"
sudo rm -rf /opt/storage/disk-03/docker/myapp-db/postgres-db-data/*

# chown to admin user
sudo chown -R admin. /opt/storage/disk-03/docker/myapp-db/postgres-db-data/
# Now removal works
sudo rm -rf /opt/storage/disk-03/docker/myapp-db/postgres-db-data/*