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Docker container, custom index.html on startup

Been dealing with this problem for 2 days already, don't understand why it won't create the file. Cannot find any info on this online.

Task

Design an apache container that creates a custom index.html file with container's hostname in it (for load balancing testing) on startup.

Basically I need it to run uname -n > /var/www/html/index.html on startup. But no matter what I do file is not created.

Tried

Running this script in Dockerfile's CMD/ENTRYPOINT:

#!/bin/bash
apachectl -DFOREGROUND
/bin/uname -n | tee /var/www/html/index.html

and

#!/bin/bash
apachectl -DFOREGROUND
/bin/uname -n > /var/www/html/index.html

Apache starts but file is not there.

But if I start container with just ENTRYPOINT and then attach to it and run the same script that was copied during build - it creates the file...

Tried keeping only ENTRYPOINT ["apachectl","-DFOREGROUND"] and running needed command with docker run ..., but then apache doesn't start and container exits right away.

I'm confused. Please, any help will be greatly appreciated.

Solution

  • apachectl -DFOREGROUND runs in the foreground. In other words, it blocks the progress of your entrypoint script until apachectl exits.

    I'm no Apache expert, but I suspect the easiest solution is to switch the order of the commands - do the uname stuff before starting Apache.