How do I create a directory in a Docker container that won't start?

Question

I have a Docker container (not image) that crashes when I try to start it. The Docker logs show that it is failing because and Apache2 conf file can't find a directory (/var/www/html/log/ - this is the result of me trying to get SSL setup and forgot to create this directory after I referenced it in the 000-default.conf file and restarted Apache).

How do I create this directory in the container without having to start the container itself?

Answer 1

You have 4.5 options that comes to my mind:

• You can rebuild the image and set up the directory while doing it.
• You can attach a volume while starting the image, but in this case your changes will remain in your disk and not in your container.
• You can run the image overriding the entry point with --entrypoint="bash" or something. You need to do it with -ti flag so that it begins in interactive mode. Then make your changes and run docker commit -p <container> <image:tag> -p pauses container while commiting. I recommend this unless it absolutely needs to be running.
• I am not sure if this one works so I give half point :P but if it does this would be the fastest option actually. You can start the container in interactive mode with docker start -i container which would attach a terminal. And if you have time until container exits or read that part of configuration, you can create the folder.
• Ah finally, I have just remembered, you should be able to move files and folders from your file system to container using docker cp [container:]<source> [container:]<destination> even while container is not running.

Answer 2

In general, if you're using a base Docker image for Apache (for example, httpd/2.4/Dockerfile), it should already have "/var/www/html/log".

SUGGESTION 1: Please make sure you're starting with a "good" base image.

SUGGESTION 2: Add "mkdir -p /var/www/html/log" to your Dockerfile, and rebuild the image.

I'm not sure how you're using your image - what you want the image to contain besides Apache - but:

SUGGESTION 3: Google for a simple tutorial that matches your use case, and see what steps you might be "missing". For example: Dockerize your Laravel Application