Port docs-no-retest from munge to prow

mungegithub/mungers/BUILD

@@ -63,7 +63,6 @@ go_library(
         "comment-deleter.go",
         "comment-deleter-jenkins.go",
         "doc.go",
-        "docs-no-retest.go",
         "inactive-review-handler.go",
         "issue-categorizer.go",
         "lgtm_after_commit.go",

prow/plugins/BUILD

@@ -47,6 +47,7 @@ filegroup(
         "//prow/plugins/assign:all-srcs",
         "//prow/plugins/cla:all-srcs",
         "//prow/plugins/close:all-srcs",
+        "//prow/plugins/docs-no-retest:all-srcs",
         "//prow/plugins/golint:all-srcs",
         "//prow/plugins/heart:all-srcs",
         "//prow/plugins/hold:all-srcs",

prow/plugins/docs-no-retest/BUILD

@@ -0,0 +1,32 @@
+load("@io_bazel_rules_go//go:def.bzl", "go_library", "go_test")
+
+go_library(
+    name = "go_default_library",
+    srcs = ["docs-no-retest.go"],
+    visibility = ["//visibility:public"],
+    deps = [
+        "//prow/github:go_default_library",
+        "//prow/plugins:go_default_library",
+    ],
+)
+
+go_test(
+    name = "go_default_test",
+    srcs = ["docs-no-retest_test.go"],
+    library = ":go_default_library",
+    deps = ["//prow/github:go_default_library"],
+)
+
+filegroup(
+    name = "package-srcs",
+    srcs = glob(["**"]),
+    tags = ["automanaged"],
+    visibility = ["//visibility:private"],
+)
+
+filegroup(
+    name = "all-srcs",
+    srcs = [":package-srcs"],
+    tags = ["automanaged"],
+    visibility = ["//visibility:public"],
+)

prow/plugins/docs-no-retest/docs-no-retest.go

@@ -0,0 +1,106 @@
+/*
+Copyright 2017 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+// Package docsnoretest contains a Prow plugin which manages a label indicating
+// whether a given pull requests only changes documentation.  In such cases it
+// would not need to be retested.
+package docsnoretest
+
+import (
+	"fmt"
+	"path"
+	"regexp"
+
+	"k8s.io/test-infra/prow/github"
+	"k8s.io/test-infra/prow/plugins"
+)
+
+const (
+	pluginName      = "docs-no-retest"
+	labelSkipRetest = "retest-not-required-docs-only"
+)
+
+var (
+	docFilesRegex    = regexp.MustCompile("^.*\\.(md|png|svg|dia)$")
+	ownersFilesRegex = regexp.MustCompile("^OWNERS$")
+)
+
+func init() {
+	plugins.RegisterPullRequestHandler(pluginName, handlePullRequest)
+}
+
+func handlePullRequest(pc plugins.PluginClient, pe github.PullRequestEvent) error {
+	return handlePR(pc.GitHubClient, pe)
+}
+
+// Strict subset of *github.Client methods.
+type githubClient interface {
+	AddLabel(owner, repo string, number int, label string) error
+	RemoveLabel(owner, repo string, number int, label string) error
+	GetIssueLabels(org, repo string, number int) ([]github.Label, error)
+	GetPullRequestChanges(org, repo string, number int) ([]github.PullRequestChange, error)
+}
+
+func handlePR(gc githubClient, pe github.PullRequestEvent) error {
+	var (
+		owner = pe.PullRequest.Base.Repo.Owner.Login
+		repo  = pe.PullRequest.Base.Repo.Name
+		num   = pe.PullRequest.Number
+	)
+
+	changes, err := gc.GetPullRequestChanges(owner, repo, num)
+	if err != nil {
+		return fmt.Errorf("cannot get pull request changes for docs_no_retest plugin: %v", err)
+	}
+
+	docsOnly := true
+	for _, change := range changes {
+		_, basename := path.Split(change.Filename)
+		if docFilesRegex.MatchString(basename) {
+			continue
+		}
+		if ownersFilesRegex.MatchString(basename) {
+			continue
+		}
+		docsOnly = false
+		break
+	}
+
+	labels, err := gc.GetIssueLabels(owner, repo, num)
+	if err != nil {
+		return fmt.Errorf("cannot get labels for docs_no_retest plugin: %v", err)
+	}
+
+	hasTargetLabel := false
+	for _, label := range labels {
+		if label.Name == labelSkipRetest {
+			hasTargetLabel = true
+			break
+		}
+	}
+
+	if docsOnly && !hasTargetLabel {
+		if err := gc.AddLabel(owner, repo, num, labelSkipRetest); err != nil {
+			return fmt.Errorf("error adding label to %s/%s PR #%d: %v", owner, repo, num, err)
+		}
+	} else if !docsOnly && hasTargetLabel {
+		if err := gc.RemoveLabel(owner, repo, num, labelSkipRetest); err != nil {
+			return fmt.Errorf("error removing label from %s/%s PR #%d: %v", owner, repo, num, err)
+		}
+	}
+
+	return nil
+}