Add ArtifactHUB pre-release annotations to the Helm chart

Signed-off-by: Richard Wall <richard.wall@jetstack.io>

deploy/charts/cert-manager/BUILD.bazel

@@ -38,6 +38,28 @@ genrule(
     visibility = ["//visibility:public"],
 )
 
+# We don't want alpha and beta releases to show on ArtifactHUB as releases.
+# To prevent pre-releases from appearing, we use the ArtifactHUB-specific:
+#
+#   annotation:
+#     artifacthub.io/prerelease: "true"
+#
+# See https://artifacthub.io/docs/topics/annotations/helm/
+genrule(
+    name = "chart-yaml",
+    srcs = [
+        "Chart.template.yaml",
+        "//:version",
+    ],
+    outs = ["Chart.yaml"],
+    cmd = """
+    IS_PRERELEASE=$$(grep -q '^v[0-9]\\+.[0-9]\\+.[0-9]\\+$$' $(location //:version) && echo "false" || echo "true")
+    sed -e "s:{{IS_PRERELEASE}}:$${IS_PRERELEASE}:g" < $(location Chart.template.yaml) > $@
+    """,
+    stamp = 1,
+    visibility = ["//visibility:public"],
+)
+
 filegroup(
     name = "chart-srcs",
     srcs = ["//deploy/charts/cert-manager/templates:chart-srcs"] + glob(

deploy/charts/cert-manager/Chart.template.yaml

@@ -16,3 +16,5 @@ sources:
 maintainers:
   - name: cert-manager-maintainers
     email: cert-manager-maintainers@googlegroups.com
+annotations:
+  artifacthub.io/prerelease: "{{IS_PRERELEASE}}"