Update the IC so that GlobalConfiguration is not mandatory when configured

[soneillf5]

Proposed changes

The globalConfig parameter for the IC was a dependency, it was parsed and validated on starting the IC.
This meant it was requirement for the helm chart and the operator. This change removes the parsing
but keeps the namespace/name definition so watchers are setup correctly, enabling GlobalConfig
resources to be added/updated/removed while the IC is running.

Checklist

Before creating a PR, run through this checklist and mark each as complete.

• I have read the CONTRIBUTING doc
• I have added tests that prove my fix is effective or that my feature works
• I have checked that all unit tests pass after adding my changes
• I have updated necessary documentation
• I have rebased my branch onto master
• I will ensure my PR is targeting the master branch and pulling from my branch from my own fork

[soneillf5]

This change means we don't need a GlobalConfig resource to start the IC.

We do need to specify the namespace/name though. What do the reviewers think about changing the default from empty string to a valid namespace/name ?

[pleshakov]

Hi @soneillf5

We do need to specify the namespace/name though. What do the reviewers think about changing the default from empty string to a valid namespace/name ?

Better to not have a default. The GlobalConfiguration is only required for TCP/UDP load balancing. Most of the people use only HTTP load balancing in the Ingress Controller, so there is no need to monitor for GlobalConfiguration resource.
Also, because multiple KICs could be deployed in the same namespace, having the same default will make those KICs depend on the same configuration, which isn't the usual case - because those are different KICs, their ConfigMaps and GlobalConfiguration will probably be different

[ciarams87]

LGTM

[pleshakov]

Hi @soneillf5

A few docs issues:

could you restore the docs for helm (both in deployments/helm-chart/README.md and https://github.com/nginxinc/kubernetes-ingress/pull/1492/files ) ?

Also, in the installation with manifests, we have

However, the file deployments/common/global-configuration.yaml was removed. It's better to leave it - it could be used as the base to add necessary listeners.

[soneillf5]

@pleshakov I've removed the reference to creating the GlobalConfig from installation-with-manifests.md to be consistent with the other custom resources.