docs(issue_template): Improve rolling HDFS upgrade instructions (#432)

Author: Techassi

.github/ISSUE_TEMPLATE/pre-release-from-scratch-testing.md

@@ -3,7 +3,7 @@ name: Pre-Release Demo Nightly Testing
 about: |
   This template can be used to track the testing of nightly demos from scratch
   leading up to the next Stackable release.
-title: "chore(tracking): Test demos on nightly versions for YY.M.X"
+title: "tracking: Test demos on nightly versions for YY.M.X"
 labels: ['epic']
 assignees: ''
 ---

.github/ISSUE_TEMPLATE/pre-release-upgrade-testing.md

@@ -3,7 +3,7 @@ name: Pre-Release Demo Upgrade Testing
 about: |
   This template can be used to track the upgrade testing of demos from stable to
   nightly leading up to the next Stackable release.
-title: "chore(tracking): Test demo upgrades on nightly versions for YY.M.X"
+title: "tracking: Test demo upgrades to nightly versions for YY.M.X"
 labels: ['epic']
 assignees: ''
 ---
@@ -125,34 +125,33 @@ kubectl patch hbaseclusters/hbase --type='json' -p='[{"op": "replace", "path": "
 # Run through the (still) nightly demo/stack instructions again.
 ```
 
-### HDFS Rolling Upgrade
+<details>
+  <summary>HDFS rolling upgrade instructions</summary>
 
-For demos that use HDFS, also test a rolling upgrade.
-See <https://docs.stackable.tech/home/nightly/hdfs/usage-guide/upgrading/>.
+  For demos that use HDFS, also test a rolling upgrade.
+  Also see <https://docs.stackable.tech/home/nightly/hdfs/usage-guide/upgrading/>
 
-#### Prepare the upgrade (run in an HDFS superuser container)
+  ```shell
+  # In some cases (eg. in the end-to-end-security demo), HDFS is kerberized.
+  # This requires these commands to be run first.
+  # Pick "nn/..."
+  klist -kt /stackable/kerberos/keytab
+  kinit -kt /stackable/kerberos/keytab <PRINCIPAL_FROM_ABOVE>
 
-```shell
-hdfs dfsadmin -rollingUpgrade prepare
-hdfs dfsadmin -rollingUpgrade query  # repeat until "Proceed with rolling upgrade"
-```
-
-#### Patch the HdfsCluster to the new product version and wait for all pods to restart and reach Ready state
-
-```shell
-kubectl patch hdfs/<CLUSTER_NAME> --type=merge \
-  --patch '{"spec": {"image": {"productVersion": "<NEW_VERSION>"}}}'
-```
+  # These commands need to be executed in a superuser environment (eg. the namenode pod)
+  hdfs dfsadmin -rollingUpgrade prepare
+  hdfs dfsadmin -rollingUpgrade query  # repeat until "Proceed with rolling upgrade"
 
-#### Finalize the upgrade (run in an HDFS superuser container)
+  # Now patch the productVersion in your regular shell
+  kubectl patch hdfs/<CLUSTER_NAME> --type=merge \
+    --patch '{"spec": {"image": {"productVersion": "<NEW_VERSION>"}}}'
 
-```shell
-hdfs dfsadmin -rollingUpgrade finalize
-```
+  # Finalize the upgrade in the namenode pod
+  # Needs another kinit because the container was restarted
+  hdfs dfsadmin -rollingUpgrade finalize
 
-#### Update the deployed product version status
+  kubectl patch hdfs/<CLUSTER_NAME> --subresource=status --type=merge \
+    --patch '{"status": {"deployedProductVersion": "<NEW_VERSION>"}}'
+  ```
 
-```shell
-kubectl patch hdfs/<CLUSTER_NAME> --subresource=status --type=merge \
-  --patch '{"status": {"deployedProductVersion": "<NEW_VERSION>"}}'
-```
+</details>

.github/ISSUE_TEMPLATE/release-from-scratch-testing.md

@@ -3,7 +3,7 @@ name: Release Demo and Upgrade Testing
 about: |
   This template can be used to track the upgrade testing of demos from the outgoing stable to
   the new release, and new release from scratch before officially marking the new release as stable.
-title: "chore(tracking): Test demos on nightly versions for YY.M.X"
+title: "tracking: Test demos on nightly versions for YY.M.X"
 labels: ['epic']
 assignees: ''
 ---

.markdownlint.yaml

@@ -18,3 +18,9 @@ MD013:
 MD024:
   # Only check sibling headings
   siblings_only: true
+
+# MD033 - no-inline-html
+MD033:
+  allowed_elements:
+    - details
+    - summary