This is a PoC and is likely not yet complete, except for a basic, initial solution:
[x] We want to think about what to do for content outside of etc -- do we add separate configmaps for each overlay? Use the global overlay?
[x] Haven't tested binary content yet
[x] Docs changes
[x] Should test with > 10 configmaps to make sure the ordering is correct
[x] Nothing is done with uncompressing content yet (or should that be a different PR? Or go into the entrypoint of the dockerfile)
[x] Is the ".uncompress" file the right way to trigger the uncompress logic? Should it always be on?
[x] Make sure we get ownership/permissions right for OpenShift in particular (it's fine for etc, but will need work in the container for other directories)
[x] Any scripting/Helm charts to help make configmaps for multiple directories--not needed with ZIP support
[x] Make sure the characters in the files we use are allowed by the configmap key regex -- nah, just toss 'em in an archive
[x] Should we support extracting archives? (zip, tar.gz) -- YES
[x] Should we do as much of this in the Docker container instead of here? -- NO, not now
[x] Add support for ZIP archives (and remove support for .gz--we'll only support one compression/archive format for simplicity and documentation)
future possibilities
Support arbitrary user-specific init containers.
Make the etc pvc optional (maybe even disabled by default eventually?)
Git workflow for editing etc files, merging changes between versions, etc..
We could possibly add support for files that can be updated while Horizon is running.
Support a zip or tar.gz of files
To test
# set your namespace first
instance=whatever
configmap=foobaz
mkdir etc
date > etc/testing-configmap
kubectl create configmap -n $instance $configmap --from-file=etc
kubectl get configmap -n $instance $configmap -o yaml
helm upgrade --reuse-values $instance . --set "core.overlayConfigMaps[0].name=$configmap" --set 'core.overlayConfigMaps[0].path=etc'
Output from the init container:
Processing overlay config maps ...
Copying files from /opennms-overlay-configmaps/0 to /opt/opennms-overlay/ ...
etc/testing-configmap c0f178d439e947ba9d62abb519fe56af
Notes
If the pod doesn't start, check events -- maybe the configmap name is wrong and can't be mounted:
kubectl events -n $instance
Remove the configmap before creating a new one:
kubectl delete configmap -n $instance $configmap
When you update the configmap, the pod will not automatically restart. You'll have to do that:
$ dd if=/dev/urandom of=etc/random-file bs=1k count=1
1+0 records in
1+0 records out
1024 bytes transferred in 0.000158 secs (6481013 bytes/sec)
$ md5sum etc/random-file
ad428160a7518cd5893bd2a6c3b09938 etc/random-file
This is a PoC and is likely not yet complete, except for a basic, initial solution:
etc, but will need work in the container for other directories)Any scripting/Helm charts to help make configmaps for multiple directories--not needed with ZIP supportfuture possibilities
To test
Output from the init container:
Notes
If the pod doesn't start, check events -- maybe the configmap name is wrong and can't be mounted:
Remove the configmap before creating a new one:
When you update the configmap, the pod will not automatically restart. You'll have to do that:
Testing
Binary content
Updating the configmap and restarting the pod:
Inside the container after updating the configmap and restarting the pod:
configmap with .zip file
Make a big file of zeros and add to a .zip file
Update the configmap and update the helm chart to unzip the configmap:
Inside the container after updating the configmap and restarting the pod:
Output from the init container: