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Kenta Takeuchi
Kenta Takeuchi

Posted on • Originally published at bmf-tech.com

Encountered 'Permission denied' Error When Starting MySQL Container on Ubuntu 20.04.2 LTS

#ubuntu #mysql #tips

This article was originally published on bmf-tech.com.

Overview

When attempting to start a MySQL container on Ubuntu 20.04.2 LTS, the following error occurs, causing the container to fail to start.

Could not open file '/var/log/mysql/mysql-error.log' for error logging: Permission denied”
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Dockerfile

The Dockerfile where the issue occurred.

docker-compose.yml (partial excerpt)

version: '3.2'
services:
  mysql:
    container_name: "example-mysql"
    env_file: ./mysql/.env
    build:
        context: "./mysql"
        dockerfile: "Dockerfile"
    ports:
      - "3306:3306"
    volumes:
      - ./mysql/data:/var/lib/mysql
      - ./mysql/initdb.d:/docker-entrypoint-initdb.d
      - ./mysql/log:/var/log/mysql
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Dockerfile

FROM --platform=linux/amd64 mysql:8.0.26

ADD ./conf.d/my.cnf /etc/mysql/conf.d/my.cnf

CMD ["mysqld"]
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Checking the Mount Source 

$ ls -la mysql
drwxrwxrwx  7 systemd-coredump example-app 4096 Sep 12 23:10 data
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An unfamiliar user named systemd-coredump appears.

systemd-coredump

Checking the user on the host, systemd-coredump has uid 999.

$ cat /etc/passwd | grep systemd-coredump
systemd-coredump:x:999:999:systemd Core Dumper:/:/usr/sbin/nologin
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The user inside the MySQL container likely has uid 999, which is probably the cause?

Solution

Add user: 1000:1000 to docker-compose.yml.

docker-compose.yml (partial excerpt)

version: '3.2'
services:
  mysql:
    container_name: "example-mysql"
    env_file: ./mysql/.env
    build:
        context: "./mysql"
        dockerfile: "Dockerfile"
    ports:
      - "3306:3306"
    volumes:
      - ./mysql/data:/var/lib/mysql
      - ./mysql/initdb.d:/docker-entrypoint-initdb.d
      - ./mysql/log:/var/log/mysql
    user: 1000:1000
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It might be better to pass the uid and gid from the host instead of hardcoding them.

Thoughts

This issue did not occur on Docker for Mac, so I'm glad I was able to notice it.

References

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