Add runtime coverage support.

hack/lib/golang.sh

@@ -474,32 +474,22 @@ kube::golang::create_coverage_dummy_test() {
   local name="$(basename "$package")"
   cat <<EOF > $(kube::golang::path_for_coverage_dummy_test "$package")
 package main
- import (
-  "flag"
-	"os"
-	"strconv"
-	"testing"
-	"time"
+import (
+  "testing"
+  "k8s.io/kubernetes/pkg/util/coverage"
 )
- func TestMain(m *testing.M) {
-  // We need to pass coverage instructions to the unittest framework, so we hijack os.Args
-  original_args := os.Args
-  now := time.Now().UnixNano()
-  test_args := []string{os.Args[0], "-test.coverprofile=/tmp/k8s-${name}-" + strconv.FormatInt(now, 10) + ".cov"}
-  os.Args = test_args
 
-  // This is sufficient for the unit tests to be set up.
-  flag.Parse()
+func TestMain(m *testing.M) {
+  // Get coverage running
+  coverage.InitCoverage("${name}")
 
-   // Restore the original args for use by the program.
-	os.Args = original_args
  	// Go!
   main()
 
-   // Make sure we actually write the profiling information to disk, if we make it here.
+  // Make sure we actually write the profiling information to disk, if we make it here.
   // On long-running services, or anything that calls os.Exit(), this is insufficient,
   // so be sure to call this from inside the binary too.
-  // TODO: actually have some code here.
+  coverage.FlushCoverage()
 }
 EOF
 }
@@ -530,6 +520,7 @@ kube::golang::build_some_binaries() {
           -covermode count \
           -coverpkg k8s.io/... \
           "${build_args[@]}" \
+          -tags coverage \
           "$package"
         kube::golang::delete_coverage_dummy_test "$package"
       else

pkg/util/coverage/coverage.go

@@ -0,0 +1,83 @@
+// +build coverage
+
+/*
+Copyright 2018 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 coverage provides tools for coverage-instrumented binaries to collect and
+// flush coverage information.
+package coverage
+
+import (
+	"flag"
+	"github.com/golang/glog"
+	"k8s.io/apimachinery/pkg/util/wait"
+	"os"
+	"testing"
+	"time"
+)
+
+const flushInterval = 5 * time.Second
+
+var coverageFile string
+
+// tempCoveragePath returns a temporary file to write coverage information to.
+// The file is in the same directory as the destination, ensuring os.Rename will work.
+func tempCoveragePath() string {
+	return coverageFile + ".tmp"
+}
+
+// InitCoverage is called from the dummy unit test to prepare Go's coverage framework.
+// Clients should never need to call it.
+func InitCoverage(name string) {
+	// We read the coverage destination in from the KUBE_COVERAGE_FILE env var,
+	// or if it's empty we just use a default in /tmp
+	coverageFile = os.Getenv("KUBE_COVERAGE_FILE")
+	if coverageFile == "" {
+		coverageFile = "/tmp/k8s-" + name + ".cov"
+	}
+
+	// Set up the unit test framework with the arguments we want.
+	flag.CommandLine.Parse([]string{"-test.coverprofile=" + tempCoveragePath()})
+
+	// Begin periodic logging
+	go wait.Forever(FlushCoverage, flushInterval)
+}
+
+// FlushCoverage flushes collected coverage information to disk.
+// The destination file is configured at startup and cannot be changed.
+// Calling this function also sends a line like "coverage: 5% of statements" to stdout.
+func FlushCoverage() {
+	// We're not actually going to run any tests, but we need Go to think we did so it writes
+	// coverage information to disk. To achieve this, we create a bunch of empty test suites and
+	// have it "run" them.
+	tests := []testing.InternalTest{}
+	benchmarks := []testing.InternalBenchmark{}
+	examples := []testing.InternalExample{}
+
+	var deps fakeTestDeps
+
+	dummyRun := testing.MainStart(deps, tests, benchmarks, examples)
+	dummyRun.Run()
+
+	// Once it writes to the temporary path, we move it to the intended path.
+	// This gets us atomic updates from the perspective of another process trying to access
+	// the file.
+	if err := os.Rename(tempCoveragePath(), coverageFile); err != nil {
+		// This should never fail, because we're in the same directory. There's also little that
+		// we can do if it does.
+		glog.Errorf("Couldn't move coverage file from %s to %s", coverageFile, tempCoveragePath())
+	}
+}

pkg/util/coverage/coverage_disabled.go

@@ -0,0 +1,29 @@
+// +build !coverage
+
+/*
+Copyright 2018 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 coverage
+
+// InitCoverage is a no-op when not running with coverage.
+func InitCoverage(name string) {
+
+}
+
+// FlushCoverage is a no-op when not running with coverage.
+func FlushCoverage() {
+
+}

pkg/util/coverage/fake_test_deps.go

@@ -0,0 +1,54 @@
+/*
+Copyright 2018 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 coverage
+
+import (
+	"io"
+)
+
+// This is an implementation of testing.testDeps. It doesn't need to do anything, because
+// no tests are actually run. It does need a concrete implementation of at least ImportPath,
+// which is called unconditionally when running tests.
+type fakeTestDeps struct{}
+
+func (fakeTestDeps) ImportPath() string {
+	return ""
+}
+
+func (fakeTestDeps) MatchString(pat, str string) (bool, error) {
+	return false, nil
+}
+
+func (fakeTestDeps) StartCPUProfile(io.Writer) error {
+	return nil
+}
+
+func (fakeTestDeps) StopCPUProfile() {}
+
+func (fakeTestDeps) StartTestLog(io.Writer) {}
+
+func (fakeTestDeps) StopTestLog() error {
+	return nil
+}
+
+func (fakeTestDeps) WriteHeapProfile(io.Writer) error {
+	return nil
+}
+
+func (fakeTestDeps) WriteProfileTo(string, io.Writer, int) error {
+	return nil
+}