Update PHP in Docker images

A container has its own PHP, separate from the server it runs on. Updating PHP on the server does not change PHP in your containers. And a container keeps running the image it was started with until you replace it, even after a newer image exists.

Check which PHP a container runs#

1. List your containers and the images they use:

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   docker ps --format 'table {{.Names}}\t{{.Image}}'
   

2. Check the PHP version inside a container. Replace my-app with the container name:

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   docker exec my-app php -v
   

3. In an image with PHP-FPM, check that too:

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   docker exec my-app php-fpm -v
   

With Docker Compose, use the service name: docker compose exec app php -v.

Know which tag your image follows#

The tag after the colon decides what you get when you pull. For the official php image:

A tag with the full version number never gets security fixes. To update, you change the number.

For an image someone else built (for your app, or a base image from another maintainer), the PHP inside comes from that maintainer. Check their release notes or the PHP version in their newest image before you rely on it.

Update a container that uses an image as it is#

Use this when your docker-compose.yml has an image: line and no build:.

1. Change the tag if it has a full version number, for example from php:8.3.30-fpm to php:8.3.36-fpm.

2. Download the new image:

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   docker compose pull
   

3. Recreate the containers with the new image:

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   docker compose up -d
   

4. Check the version again: docker compose exec app php -v.

Without Compose, docker pull the image, then stop and remove the old container and start a new one with the same options. Make sure its data is in a volume or bind mount first, or it is lost with the container.

Rebuild an image you build yourself#

Use this when you have a Dockerfile that starts with something like FROM php:8.3-fpm.

1. If the FROM line has a full version number, raise it.

2. Build again, and make Docker download the newest base image instead of using the copy it has:

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   docker compose build --pull
   

   Without Compose: docker build --pull -t my-app .

3. Recreate the containers:

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   docker compose up -d
   

4. Check the version inside the new container.

Settings for PHP in the official image#

In the official php image, extra ini files go in $PHP_INI_DIR/conf.d/ (that is /usr/local/etc/php/conf.d/). To add a setting, for example the emergency measure from PHP2Shell: patch CVE-2026-109618 and CVE-2026-109619, add a line to your Dockerfile:

RUN echo 'session.upload_progress.enabled = 0' > "$PHP_INI_DIR/conf.d/99-emergency.ini"

Then rebuild and recreate the container as above. A file you only change inside a running container is gone at the next recreate.

Clean up old images#

Old images stay on disk after an update. When you pull a newer image under the same tag, the old one loses its tag. To remove images without a tag:

docker image prune

It asks for confirmation first. docker image prune -a goes further and removes every image no container uses; only run that if you are sure you do not need them.