Files created during docker build not present in container created from image

General Discussions
1

I have the following Dockerfile

FROM wordpress

#make sure necessary tools for publishing are installed
RUN curl -sL https://deb.nodesource.com/setup_4.x | bash - && \
	apt-get install -y nodejs git && \
	npm install -g npm gulp bower

ADD . /var/www/html/wp-content/themes/new-theme

RUN cd /var/www/html/wp-content/themes/new-theme \
	&& npm install \
	&& npm run build \
	&& rm -rf node_modules \
	&& rm -rf bower_components \
	&& find ./* -type f -printf "%h%f\n" | sort \
	&& cd /

VOLUME ["/var/www/html/wp-content/themes/new-theme"]

ENTRYPOINT ["/entrypoint.sh"]
CMD ["apache2-foreground"]

When I build it, the second RUN command produces several files that get dropped into the /var/www/html/wp-content/themes/ca-ticket.com/dist folder, and when I view the build log I can see clearly that the files are getting created (that is why the find ./* -type f -printf "%h%f\n" | sort is there.

From the log:

build	11-Apr-2016 18:51:01	./dist/scriptsjquery.js
build	11-Apr-2016 18:51:01	./dist/scriptsjquery.js.map
build	11-Apr-2016 18:51:01	./dist/scriptsmain.js
build	11-Apr-2016 18:51:01	./dist/scriptsmain.js.map
build	11-Apr-2016 18:51:01	./dist/stylesmain.css
build	11-Apr-2016 18:51:01	./dist/stylesmain.css.map

… and so on.

However, when I create a container from this image, the /var/www/html/wp-content/themes/ca-ticket.com/dist simply doesn’t exist!

The build command is:

docker build --force-rm=true --tag="<tag here>" /path/to/context

I’ve also tried with the --no-cache option with no change to the result.

I’m running the image with:

docker run --name <name> -d -p 81:80 -e WORDPRESS_DB_HOST=<dbhost> -e WORDPRESS_DB_USER=<dbuser> -e WORDPRESS_DB_PASSWORD=<pass> -e WORDPRESS_DB_NAME=<dbname> -e WORDPRESS_TABLE_PREFIX=<tblprefix> <imagename>

I’m suspect I must be doing something silly to cause docker to ignore a layer, but I’m not sure what is wrong about this process.

2

You have VOLUME ["/var/www/html/wp-content/themes/new-theme"]. That means a volume will be mounted in that location when you run the image. Volumes are just bind mounts. When something is mounted to a directory, it hides any contents of that directory.

You may want to put that VOLUME somewhere else.

3

But the files that get added in the ADD stage are all present at the same path when I do a docker exec -t -i <containername> bash and ls /var/www/html/wp-content/themes/new-theme - the only missing files are those that get generated during the subsequent RUN.

I just tried re-running with the volume commented out with the exact same outcome. I have the volume there because when I am doing dev work I mount the volume to a local path for me to work on the theme, but when publishing the image I run without the volume at all.

4

If you have VOLUME in the dockerfile, that location will always be a volume.

What are the exact commands you are using for the docker build and docker run ?

5

The build command is:

docker build --force-rm=true --tag="<tag here>" /path/to/context

I’ve also tried with the --no-cache option with no change to the result.

I’m running the image with:

docker run --name <name> -d -p 81:80 -e WORDPRESS_DB_HOST=<dbhost> -e WORDPRESS_DB_USER=<dbuser> -e WORDPRESS_DB_PASSWORD=<pass> -e WORDPRESS_DB_NAME=<dbname> -e WORDPRESS_TABLE_PREFIX=<tblprefix> <imagename>

I’m currently trying to do a full rebuild (--no-cache) with the volume removed.

6

Do a docker inpsect on the running container that has a problem-- does it list a volume in that location?

7

Just completed a build with the volume commented out, and docker inspect shows:

"Volumes": { "/var/www/html": {} },

That volume comes from the base wordpress image, and as you can see the volume I was adding is no longer present.

The contents of the npm run build output are still not present.

I’m hesitant to post it because it it quite large, but I can post the entire output of the docker build itself if you think that’d be helpful.

8

Is it possible I’m experiencing an issue similar to https://github.com/docker/docker/issues/3639 ?

There is a volume created in the base image, which I am copying files to, and those files do not seem to be present.

9

Ah yes,

The wordpress container will do a bunch of black magic with /var/www/html. Due to wordpress’s approach in keeping state on the filesystem, the wordpress’s entrypoint.sh script will populate it with a vanilla wordpress install at runtime.

Any changes to that location at build time are masked by the /var/www/html volume.

What you might have to do is ADD your files to another location, and then get the wordpress entrypoint.sh script to set up a symlink at runtime after doing the initial wordpress download/install.

The wordpress image’s entrypoint script can be found here: https://github.com/docker-library/wordpress/blob/master/docker-entrypoint.sh

10

I’ve currently just folded their Dockerfile into my own and removed the extra VOLUME - if this works I may have to just fork their dockerfile and do exactly what you suggested.

Thank you so much for the help; can be tough working in a vacuum!

11

Oh - crap. Now I see what you mean with the black magic / keeping state. It needs the volume to function. Symlinks it is!