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Update php.ini when using a Docker image

· 3 min read
Christophe
Christophe
Markdown, WSL and Docker lover ~ PHP developer ~ Insatiable curious.

Update php.ini when using a Docker image

This article aims to answer the following situation: I'm using a Docker image to run my website and I should modify the php.ini file; how do I do this?

A real-world example is: you've followed my article Create your Joomla website using Docker and everything is working fine. The website is running and you wish, using the Joomla administration web interface, upload a big file to your site. But, then, you get an error The selected file cannot be transferred because it is larger than the maximum upload size allowed.

Your PHP settings before changes

One of the easiest ways to do is to create a .ini file on your disk and share the file with your container.

Most probably, you'll have a docker-compose.yml file, please edit the file.

For the illustration, below you'll find a copy of the simplest docker-compose.yml file you can retrieve in my Create your Joomla website using Docker blog post. You can have yours of course. This is just for example.

services:
  joomla:
    image: joomla
    restart: always
    ports:
      - 8080:80
    environment:
      - JOOMLA_DB_HOST=joomladb
      - JOOMLA_DB_PASSWORD=example

  joomladb:
    image: mysql:8.0.13
    restart: always
    environment:
      - MYSQL_ROOT_PASSWORD=example

Step one - Update your yaml file​

The solution is to add the volumes line if not yet present in your file and, the most important one, the line for overriding the php.ini file like below:

services:
  joomla:
    image: joomla
    restart: always
    ports:
      - 8080:80
    environment:
      - JOOMLA_DB_HOST=joomladb
      - JOOMLA_DB_PASSWORD=example
    volumes:
      - ./php.ini:/usr/local/etc/php/php.ini

  joomladb:
    image: mysql:8.0.13
    restart: always
    environment:
      - MYSQL_ROOT_PASSWORD=example

Step two - Create your own php.ini file​

The second things to do is to create a file called php.ini in the same folder of your docker-compose.yml where you'll define your variables; f.i.

file_uploads = On
memory_limit = 500M
upload_max_filesize = 500M
post_max_size = 500M
max_execution_time = 600

So, now, your folder contains at least two files:

❯ pwd
/tmp/joomla

❯ ls -alh
Permissions Size User       Group      Date Modified    Name
drwxr-xr-x     - christophe christophe 2023-11-04 09:32  .
drwxrwxrwt     - christophe christophe 2023-11-04 09:32 ..
.rw-r--r--   325 christophe christophe 2023-11-04 09:32 docker-compose.yml
-rw-r--r--     1 christophe christophe 2023-12-22 19:51 php.ini

Step three - Restart your container​

This done, just run docker compose down ; docker compose up --detach in your terminal to stop your current container(s) and restart it/them.

Now, when restarting, Docker will take into account your latest changes and update accordingly the php.ini file that is present in Docker.

Your PHP settings after changes