Debugging

For Docker Apps, debugging takes one more step.

Important

Remember that for Docker Apps, many files will be available only in the container. If you want to examine your log files, they will not be found where they used to be. Instead you always need to log into the container.

Debugging the installation process

If something goes wrong really badly (like the installation of packages fails), the App Center tries to revert the installation. In case of the installation of Docker Apps, it will remove the the container.

This means you cannot look into it to see what exactly happened. For testing purposes you may use the undocumented options --do-not-revert:

univention-app install myapp --do-not-revert

This will leave you with a running, yet somewhat "unconfigured" container.

Getting into the container

For debugging installations problems, but also for supporting customers, you will need to use the container. To get closer to your App, you can do

univention-app shell myapp

This will open /bin/bash in the container. If your container does not support this, you can still use the "hard way":

CONTAINER="$(ucr get appcenter/apps/myapp/container)"
docker exec "$CONTAINER" ...

From there, you can interact with your App as always.

Log files

Maybe it is sufficient to look into the log files to know what went wrong. Important log files are:

• /var/log/univention/appcenter.log
• /var/log/univention/management-console-module-appcenter.log (if you installed the App via the UMC module - which is actually a good idea as users will install it that way, too).
• /var/log/docker.log