Only download kubectl and provide volume if graylog version is < 4.2.0-0

[tuxBurner]

Only download kubectl and provide volume if graylog version is < 4.2.0-0

I recognized that the kubectl is always downloaded. But it is only used in the lifecycle whe tne graylog version is < 4.2.0-0

Which issue this PR fixes

Special notes for your reviewer

Checklist

• [x ] DCO signed
• [ x] Chart Version bumped

[KongZ]

The kubectl is using for setting the label to master node. The chart uses label mechanism to choose the master node.

[tuxBurner]

Aaah okay sorry have overseen this

[tuxBurner]

@KongZ do we really need this mechamism ?

As stated in https://go2docs.graylog.org/5-0/downloading_and_installing_graylog/docker_installation.htm#KubernetesAutomaticMasterSelection we only need to set the POD_NAME env var.

The /docker-entrypoint.sh has a part like this

# check if we are inside kubernetes, Graylog should be run as statefulset and $POD_NAME env var should be defined like this
#          env:
#          - name: POD_NAME
#            valueFrom:
#              fieldRef:
#                fieldPath: metadata.name
# First stateful member is having pod name ended with -0, so
if [[ ! -z "${POD_NAME}" ]]
then
 if echo "${POD_NAME}" | grep "\\-0$" >/dev/null
 then
   export GRAYLOG_IS_LEADER="true"
 else
   export GRAYLOG_IS_LEADER="false"
 fi
fi

[KongZ]

The solution described in the doc above will hard-code pod-0 to be the master.
The solution in this chart will automatically set the other pod to be the master if pod-0 is unable to run.
Yes, it is not necessary if pod-0 is always running. The chart was originally created from Graylog version 2 where the container and application may not be stable. The mechanism to elect the master from the other pod was necessary. 

I believe the recent Graylog versions are stable and we should be able to use pod-0 as the master but I do not have a chance to test them. 

[tuxBurner]

@KongZ i commented your script out which determines which is the master node and added the suggested env var POD_NAME

It works on my installation :)

[metron2]

I'm using this change as well and it works much better, especially with the pod security settings (chown is disallowed) but I get an error that there are multiple leaders in the cluster.

[KongZ]

@tuxBurner sorry for being late. Instead of commenting out, it would be better to delete them from manifest.

[KongZ]

The Graylog 4 is very out of date. We can say the chart no longer supports Graylog version < 4.2.
You can remove all kubectl related.

[KongZ]

Please bump chart version one more.

[metron2]

@KongZ can close this out now