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Using PHP with Volume Mounting in Docker Containers

In this lecture we're going to create an ephemeral PHP file and then a persistent PHP file through volume mounting.

Video Walkthrough

Text Walkthrough

docker run -it --rm --name my-running-script php:7.2-cli /bin/bash
  • Downloads the official php 7.2 cli image
  • Runs an interactive shell inside
  • --rm will remove the container once /bin/bash stops (exiting the container)
php -m
  • Get the installed modules
php -i
  • Get the config of the PHP cli
echo '<? echo "test text\n";' > ~/index.php
  • This will write <? echo "text text\n"; into the index.php file in the home directory of root
  • Let's execute this
php ~/index.php
  • Should print now "test text"
  • Will end the container, but will also remove the container (including our index.php) because of the --rm flag
  • This is where mounting an external host directory comes in handy
docker run -it --rm -v ${PWD}:/myfiles --name my-running-script php:7.0-cli /bin/bash
  • Now we are running the php 7.0, not the php 7.2 cli, because we can (no particular reason)
  • And we are mounting the root directory into the /myfiles directory inside the container
echo '<? echo "test text\n";' > /myfiles/index.php
  • This creates the same index.php, but this time inside /myfiles.
  • Observe the host directory, you will get a new file there as well
php /myfiles/index.php
  • This should run index.php with the php 7.0 interpreter
  • We can safely exit again, because our file is securely stored on the host. It will not be destroyed with the container upon exiting
  • If we re-run it, we can conveniently map the same file into another container
docker run -it --rm -v ${PWD}:/myfiles --name my-running-script php:7.2-cli /bin/bash
  • Let's re-run the 7.2-cli container
  • This time with the same directory mounted in /myfiles
php /myfiles/index.php
  • This allows you to execute the same script with another PHP version
  • Let's exit the container

Working Directory

Remember, we used the working directory before. Let's use it again:

docker run -it --rm -v ${PWD}:/myfiles -w /myfiles --name my-running-script php:7.2-cli php index.php
  • Will directly run index.php and output the "test text" and exit again
  • No need to actually enter the container
  • -w flag again sets the working directory to /myfiles

Last update: May 29, 2022