deploy: test with Kubernetes 1.21 instead of 1.18

The deployments for 1.18 get removed in favor of testing with 1.21.
For the two versions which get tested pre-merge, testing of both
"production" and "testing" deployments gets restored the way it
was originally intended (more tests on main worker, less on newly
spawned worker).

Author: pohly

Jenkinsfile

@@ -174,45 +174,48 @@ pipeline {
 
         // Some stages are skipped entirely when testing PRs, the
         // others skip certain tests in that case:
-        // - production deployment is only tested with Kubernetes 1.16
-        //   and testing deployment only with Kubernetes 1.18
+        // - production deployment is tested on the oldest supported Kubernetes
+        //   (less tests, runs faster)
+        // - testing deployment is tested on the newest supported Kubernetes
+        //   (more tests, runs longer, thus gets to use the existing worker)
         stage('Testing') {
             parallel {
-                // This runs most tests and thus gets to use the initial worker immediately.
-                stage('1.20') {
+                stage('1.21') {
                     options {
                         timeout(time: 12, unit: "HOURS")
                     }
                     steps {
-                        TestInVM("", "fedora", "", "1.20", "Top.Level..[[:alpha:]]*-production[[:space:]]")
+                        // Skip production, i.e. run testing.
+                        TestInVM("", "fedora", "", "1.21", "Top.Level..[[:alpha:]]*-production[[:space:]]")
                     }
                 }
 
                 // All others set up their own worker.
-                stage('1.19') {
+                stage('1.20') {
+                    when {
+		        beforeAgent true
+		        not { changeRequest() }
+                    }
                     options {
                         timeout(time: 12, unit: "HOURS")
                     }
                     agent {
                         label "pmem-csi"
                     }
                     steps {
-                        TestInVM("fedora-1.19", "fedora", "", "1.19", "Top.Level..[[:alpha:]]*-production[[:space:]]")
+                        TestInVM("fedora-1.20", "fedora", "", "1.20", "")
                     }
                 }
-                stage('1.18') {
-                    when {
-		        beforeAgent true
-		        not { changeRequest() }
-                    }
+                stage('1.19') {
                     options {
                         timeout(time: 12, unit: "HOURS")
                     }
                     agent {
                         label "pmem-csi"
                     }
                     steps {
-                        TestInVM("fedora-1.18", "fedora", "", "1.18", "")
+                        // Skip testing, i.e. run production.
+                        TestInVM("fedora-1.19", "fedora", "", "1.19",  "Top.Level..[[:alpha:]]*-testing[[:space:]]")
                     }
                 }
             }

Makefile

@@ -167,9 +167,9 @@ KUSTOMIZE_KUBERNETES_OUTPUT = \
     deploy/kubernetes-X.XX/pmem-csi-lvm-testing.yaml=deploy/kustomize/kubernetes-base-lvm-coverage \
 
 KUSTOMIZE_KUBERNETES_VERSIONS = \
-    1.18 \
     1.19 \
     1.20 \
+    1.21
 
 KUSTOMIZE += $(foreach version,$(KUSTOMIZE_KUBERNETES_VERSIONS),$(subst X.XX,$(version),$(KUSTOMIZE_KUBERNETES_OUTPUT)))