deploy: fix CSIStorageCapacity version check

Checking via "kubectl get" and parsing its output was broken in
combination with "-o pipefail" because then the overall result of the
pipe was false even when the expected error occurred. Checking the
output of "kubectl api-resources" and failing the install when that
command fails (i.e. not using it inside an if) is better.

The check also failed on clusters that had the v1beta1 API but not the
v1alpha1. We need to be very careful about which version we need for
the external-provisioner that is going to be installed. Unfortunately
some heuristics are needed to determine that.

Author: pohly

deploy/kubernetes-distributed/deploy.sh

@@ -136,11 +136,21 @@ for component in CSI_PROVISIONER; do
     run kubectl apply -f "${current}"
 done
 
-if kubectl get csistoragecapacities 2>&1 | grep "the server doesn't have a resource type"; then
-    have_csistoragecapacity=false
-else
+# The cluster must support exactly the version that the external-provisioner supports.
+# The problem then becomes that the version of the external-provisioner might get
+# changed via CSI_PROVISIONER_TAG, so we cannot just check for the version currently
+# listed in the YAML file.
+case "$CSI_PROVISIONER_TAG" in
+    "") csistoragecapacities_api=v1alpha1;; # unchanged, assume version from YAML
+    *) csistoragecapacities_api=v1beta1;; # set, assume that it is more recent *and* a version that uses v1beta1 (https://github.com/kubernetes-csi/external-provisioner/pull/584)
+esac
+resources=$(kubectl api-resources)
+if echo "$resources" | grep -q "csistoragecapacities.*storage.k8s.io/$csistoragecapacities_api"; then
     have_csistoragecapacity=true
+else
+    have_csistoragecapacity=false
 fi
+echo "deploying with CSIStorageCapacity: $have_csistoragecapacity"
 
 # deploy hostpath plugin and registrar sidecar
 echo "deploying hostpath components"