Fix OVNKubernetes alert rules for OpenShift 4.14

OpenShift 4.14 moved the OVNKubernetes control plane alerts (and we
can't use the 4.13 alerts, because 4.14 makes significant changes to the
OVNKubernetes architecture). Additionally 4.14 introduced gotemplate
snippets in the OVNKubernetes alerts that we need to render.

Since the files also contain gotemplate snippets which aren't valid
Jinja2, we implement very simple rendering logic which uses
`std.strReplace()` in the component.

class/openshift4-monitoring.yml

@@ -47,9 +47,15 @@ parameters:
           control_plane: https://raw.githubusercontent.com/openshift/cluster-network-operator/${openshift4_monitoring:manifests_version}/bindata/network/ovn-kubernetes/self-hosted/alert-rules-control-plane.yaml
         release-4.14:
           common: https://raw.githubusercontent.com/openshift/cluster-network-operator/${openshift4_monitoring:manifests_version}/bindata/network/ovn-kubernetes/common/alert-rules.yaml
-          # We use the "self-hosted" variant of the control-plane alerts, so
-          # we don't have to worry about unresolved gotemplate references.
-          control_plane: https://raw.githubusercontent.com/openshift/cluster-network-operator/release-4.13/bindata/network/ovn-kubernetes/self-hosted/alert-rules-control-plane.yaml
+          # We handle the gotemplate stuff in Jsonnet for now, since Jinja
+          # can't deal with gotemplate expressions like `{{.OvnkubeMasterReplicas}}`.
+          # The only templates that are in the alerting rules can be handled
+          # with a simple string replace.
+          # By default we use the `multi-zone-interconnect` rules for 4.14,
+          # since those rules match the rules that are deployed by default
+          # when selecting OVNKubernetes as the network plugin during
+          # installation.
+          control_plane: https://raw.githubusercontent.com/openshift/cluster-network-operator/release-4.14/bindata/network/ovn-kubernetes/self-hosted/multi-zone-interconnect/alert-rules-control-plane.yaml
 
   kapitan:
     dependencies:

component/rules.jsonnet

@@ -52,6 +52,40 @@ local upstreamManifests = std.flattenArrays(
   ]
 );
 
+// Currently this function can only render the following gotemplate
+// expressions:
+// * '{{"{{"}}' -> '{{'
+// * '{{"}}"}}' -> '}}'
+local simpleRenderGoTemplate(groups) =
+  // We only try to render gotemplates in the rule groups listed in this
+  // variable.
+  local rulegroups = [
+    'cluster-network-operator-master.rules',
+    'cluster-network-operator-ovn.rules',
+  ];
+  [
+    if std.member(rulegroups, g.name) then
+      g {
+        rules: [
+          if std.objectHas(r, 'alert') then
+            // only try to render templates in alerting rules
+            r {
+              annotations+: {
+                summary: std.strReplace(
+                  std.strReplace(r.annotations.summary, '{{"{{"}}', '{{'), '{{"}}"}}', '}}'
+                ),
+              },
+            }
+          else
+            r
+          for r in g.rules
+        ],
+      }
+    else
+      g
+    for g in groups
+  ];
+
 local additionalRules = {
   spec+: {
     groups+: [ {
@@ -84,7 +118,9 @@ local additionalRules = {
       function(obj)
         if com.getValueOrDefault(obj, 'kind', '') == 'PrometheusRule' then
           // handle case for empty PrometheusRule objects
-          com.getValueOrDefault(obj, 'spec', { groups: [] }).groups
+          local groups =
+            com.getValueOrDefault(obj, 'spec', { groups: [] }).groups;
+          simpleRenderGoTemplate(groups)
         else if std.objectHas(obj, 'groups') then
           obj.groups
         else