Volume storage not available while building from Docker image?
I'm looking to deploy the
mediawiki Docker image as a service. After deploying, it correctly starts up apache as a web service, and the first connection is then walked through a MediaWiki set-up process that asks for relevant info like DB authentication and customizable options for the website. At the end of the process, a file LocalSettings.php is generated that must be manually downloaded and then re-uploaded to the root folder for the website (i.e., /var/www/html).
Since this calls for persistent information to be available between re-deploys of the service, it calls for a volume. But whenever I attach a volume, it appears to clobber the contents of /var/www/html that already exist in the container: after mounting a new volume to my service in Railway, attempting to connect to the website gives me a 'Forbidden' access error since it cannot find index.php. This also happens when I mount the volume to an empty service before loading the MediaWiki docker image.
Is there a proper way to mount a volume that would let me persist files generated by the container's build process alongside a new file like LocalSettings.php that I could add later (perhaps through the FileBrowser template)?Solution:Jump to solution
I'm interested in MediaWiki despite its design flaws (as well as learning a bit about Docker and Railway along the way) which means I need to be able to access
/var/www/html on my volume. A mounted volume in Railway can only be accessed by the app after the container is running. With the default MediaWiki DockerHub image, I note that the actual MediaWiki "install" portion basically amounts to downloading a tarball using curl and extracting it into /var/www/html, something that doesn't work if that's where the volume is mounted.
My work-around is to use a custom Dockerfile hosted on a private repo that is a copy of the MediaWiki file with a few key lines added. The end result is that the MW files end up untarred into a temp directory, and an executable shell script is used as the main CMD entrypoint instead of running apache. This shell script first copies all of the MW files from the temp directory into /var/www/html (which will now be the mounted volume, at "runtime" for the container), deletes the temp directory, then runs the apache server as per usual....33 Replies
Project ID:
N/AN/A
the volume is not available during build, but I don't think that's the issue here
you are deploying a docker image, there really isn't a build stage since the image is already built
Fair point about the build part not being the issue. But the underlying issue remains, that I can't seem to attach a volume without it changing/removing what's already there.
I can deploy a container locally doing something like
docker run -d ... --mount source=myvolume,target=/var/www/html mediawiki:latest
and this works as I would have expected.
But I'm not sure how to achieve the same effect on Railway.mediawiki needs two volumes, and wants a volume mounted to
/var/www/html/LocalSettings.php never a good idea in the first place, so i dont think you will be able to run this on railwayI’ll take you at your word that it might not be possible on Railway atm.
But can you elaborate on what you mean by mediawiki needing two volumes?
my bad i thought you would have seen the dockercompose file
https://hub.docker.com/_/mediawiki
I saw that docker compose file, but isn't that just an example compose file? The paragraph above specifies that the dockerhub image doesn't include any volumes.
And since both the images directory and the LocalSettings.php file itself are contained within
/var/www/html I would have thought it sufficient for deploying on Railway (if not exactly the intention for the dockerhub image) that I optionally include a single volume mounted at /var/www/html, encapsulating both the images dir and LocalSettings file.guess mediawiki is setup in a way that mounting to that breaks
😦
This only happens on Railway though. As I mentioned, using the same image from dockerhub and running on my own PC
docker run... with the same mount point gives me a working container that behaves as expected: all of the usual stuff that MediaWiki puts in /var/www/html is present and accounted for, except it's all sitting on the mounted volume. At that point I can add the LocalSettings file and know it will persist. I don't know why this isn't possible on Railway.just because something doesn't work on Railway doesn't always mean railway is at fault, I've setup a few php based apps with volumes mounted to /var/www/html without issues
I've looked at this some more and while I can't say for certain the fault lies with Railway, I'm at a loss for what else could be the issue.
Based on the mediawiki Dockerfile source used to generate their image
https://github.com/wikimedia/mediawiki-docker/blob/fdf347f62615dad789d0e703fc2f6d628c43d4e1/1.40/apache/Dockerfile
I've broken things down to the simplest case that results in the service not running as expected:
Using that custom Dockerfile in a new service, I am able to successfully run this on Railway and accessing the generated domain gives me the expected 'Hello world' page.
However, mounting a volume to
/var/www/html on that same service then trying to run with no other changes, I receive a 403-Forbidden error along with this entry in my my Deploy logs on Railway:
AH01276: Cannot serve directory /var/www/html/: No matching DirectoryIndex (index.php,index.html) found, and server-generated directory index forbidden by Options directiveattaching a volume to a mount point that already has files will resulting in that folder having no files since the volume is empty
This also occurs when mounting the volume before building the image
of course