Kubernetes refactoring #450
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This was referenced Nov 15, 2024
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aaannz
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Nov 18, 2024
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| var noSSLPaths = []string{ | ||
| "/pub", | ||
| "/rhn/([^/])+/DownloadFile", | ||
| "/(rhn/)?rpc/api", | ||
| "/rhn/errors", | ||
| "/rhn/ty/TinyUrl", | ||
| "/rhn/websocket", | ||
| "/rhn/metrics", | ||
| "/cobbler_api", | ||
| "/cblr", | ||
| "/httpboot", | ||
| "/images", | ||
| "/cobbler", | ||
| "/os-images", | ||
| "/tftp", | ||
| "/docs", | ||
| } |
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This will need some crosslink with relevant parts of uyuni code so we know when remove/add here where else it should be checked.
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Yes, but sadly I don't see how we could improve this as long as we have SSL handled inside the container for podman and outside for Kubernetes.
During a migration to kubernetes the server is deployed after the rsync to prepare the SSL secrets and PVC. This has the nasty effect to corrupt the synchronized data with a too recent catalog version ID. This would let the DB migration to fail starting the old postgresql server. To workaround this, move the data to the the backup place after the rsync instead of the begining of the db upgrade.
After the k8s migration the pod has been started again since the initial connection creation. We need to reset the connection to not search for the old pod name.
Some pods require a long time to run. This is the case for the DB upgrade finalization that runs a potentially long reindex.
Of of the issuers creation function had two distinct behaviors and this was only generating confusion when reading the whole code. This function has been split and some useless intermediary functions have been merged. This with better function naming should make the SSL setup code more understandable.
In the kubernetes world we need to link the ports to services. For now we only have a TCP and an UDP service for server and the same for proxy, but in the short term, we will need more services to allow splitting into multiple pods. This refactoring is preparing this split.
Running commands in a running container only works if there is a running container and is harder to unit test. In order to help sharing code for Kubernetes, the SanityCheck now gets the existing deployment version with inspecting its image. This also helps adding unit tests for those checks.
In order to later share code between those 3 very similar commands, we need to share the parameters data structure.
Migration to kubernetes is rather fragile, with:
1. tasks running in `kubectl exec` or as `pod`.
2. the uyuni helm chart being deployed multiple times
3. `hostPath` mounts are used everywhere for the scripts to run and
data to read and force the script to run on the cluster node.
Here are the solutions to those problems:
1. Each step will run as a Job and those won't be deleted automatically
for the user to access their logs after.
2. Stop using the helm chart and deploy the resources when we need them.
This will allow more control of what runs when and reduces the number
of useless starts of the giant container.
Postgresql DB upgrade will disable SSL temporarily in the
postgresql.conf in order to not rely on the SSL certificates to be
migrated.
3. The scripts to run for each step will be passed directly as `sh -c`
parameter to the generated Jobs.
The migration data are be stored in a special volume and not on the
host.
As a collateral, SSH agent can no longer be used as that would require
running on a cluster node again. The tool now creates a ConfigMap to
store the SSH config and known_hosts and a Secret for a passwordless
SSH key.
The PersistentVolumes are not destroyed after the end of the first job
and are then reused by the next ones and the final deployment.
Using Kubernetes API modules also helps for code reuse with a future
operator.
Note that the old postgresql database cannot be moved to a separate
PersistentVolumes. As we run a `db_upgrade --link`, the old database is
linked by the new one and cannot be disposed of.
In order to share the same code for installation, migration and upgrade the RunSetup() function needs to move to the mgradm shared utils module.
Remove all server resources without relying on the helm chart.
Refactor upgrade and install of the server to no longer need the helm chart as initiated for the migration, but merge all those logics into a single Reconcile() function to avoid redundancy. Merging the code into a single function will also help figuring out how to implement an operator in the future.
There is no need to run a potentially lengthy reindexing on minor upgrades, only on major ones. Don't call su with `-` parameter as it shows the warning message for terminals... and that looks ugly in logs.
Since helm is no longer used installing Uyuni, but only cert-manager, rename the flags. Also drop those that are no longer used for the server after the refactoring.
With CGO enabled there are include problems on that architecture and that would probably require cross-compiling.
Traefik helm chart changed the structure of the expose property starting version 27. Read the chart version from the trafik.yaml file and write the config accordingly.
Running the first user creation from outside the container relies on the pod to be seen as ready by kubernetes... and sometimes it takes longer than others. Calling the API from the setup script inside the container allows to use localhost and not rely on ingress to route the request.
During the installation, there was a message indicating that the timezone from the host couldn't be set in the container. This was due to no removing the line end from the command output.
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What does this PR change?
The installation, migration, upgrade and uninstall for Kubernetes has been refactored to:
Reconcile()function.This PR paves the way for the transition to an operator and improves the reliability of migrations.
As a collateral, SSH agent can no longer be used as that would require
running on a cluster node again. The tool creates a
ConfigMapto store the SSH config andknown_hostsand aSecretfor a password-less SSH key.
Using Kubernetes API modules also helps for code reuse with a future operator.
Test coverage
Unit tests were added
DONE
Links
Issue(s): #431 #432 #433 #436
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