added health probes

Author: GrigoriyMikhalkin

pkg/healthz/doc.go

@@ -0,0 +1,28 @@
+/*
+Copyright 2014 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.
+*/
+
+// This package is almost exact copy of apiserver's healthz package:
+//   https://github.com/kubernetes/apiserver/tree/master/pkg/server/healthz
+//
+// Except that LogHealthz checker removed
+// and some style fixes is made to satisfy linters
+package healthz
+
+import (
+	logf "sigs.k8s.io/controller-runtime/pkg/internal/log"
+)
+
+var log = logf.RuntimeLog.WithName("healthz")

pkg/healthz/healthz.go

@@ -0,0 +1,185 @@
+/*
+Copyright 2014 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 healthz
+
+import (
+	"bytes"
+	"fmt"
+	"net/http"
+	"strings"
+
+	"k8s.io/apimachinery/pkg/util/sets"
+)
+
+// HealthzChecker is a named healthz checker.
+type Checker interface {
+	Name() string
+	Check(req *http.Request) error
+}
+
+// PingHealthz returns true automatically when checked
+var PingHealthz Checker = ping{}
+
+// ping implements the simplest possible healthz checker.
+type ping struct{}
+
+func (ping) Name() string {
+	return "ping"
+}
+
+// PingHealthz is a health check that returns true.
+func (ping) Check(_ *http.Request) error {
+	return nil
+}
+
+// NamedCheck returns a healthz checker for the given name and function.
+func NamedCheck(name string, check func(r *http.Request) error) Checker {
+	return &healthzCheck{name, check}
+}
+
+// InstallPathHandler registers handlers for health checking on
+// a specific path to mux. *All handlers* for the path must be
+// specified in exactly one call to InstallPathHandler. Calling
+// InstallPathHandler more than once for the same path and mux will
+// result in a panic.
+func InstallPathHandler(mux mux, path string, checks ...Checker) {
+	if len(checks) == 0 {
+		log.V(5).Info("No default health checks specified. Installing the ping handler.")
+		checks = []Checker{PingHealthz}
+	}
+
+	log.V(5).Info("Installing healthz checkers:", formatQuoted(checkerNames(checks...)...))
+
+	mux.Handle(path, handleRootHealthz(checks...))
+	for _, check := range checks {
+		mux.Handle(fmt.Sprintf("%s/%v", path, check.Name()), adaptCheckToHandler(check.Check))
+	}
+}
+
+// mux is an interface describing the methods InstallHandler requires.
+type mux interface {
+	Handle(pattern string, handler http.Handler)
+}
+
+// healthzCheck implements HealthzChecker on an arbitrary name and check function.
+type healthzCheck struct {
+	name  string
+	check func(r *http.Request) error
+}
+
+var _ Checker = &healthzCheck{}
+
+func (c *healthzCheck) Name() string {
+	return c.name
+}
+
+func (c *healthzCheck) Check(r *http.Request) error {
+	return c.check(r)
+}
+
+// getExcludedChecks extracts the health check names to be excluded from the query param
+func getExcludedChecks(r *http.Request) sets.String {
+	checks, found := r.URL.Query()["exclude"]
+	if found {
+		return sets.NewString(checks...)
+	}
+	return sets.NewString()
+}
+
+// handleRootHealthz returns an http.HandlerFunc that serves the provided checks.
+func handleRootHealthz(checks ...Checker) http.HandlerFunc {
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		failed := false
+		excluded := getExcludedChecks(r)
+		var verboseOut bytes.Buffer
+		for _, check := range checks {
+			// no-op the check if we've specified we want to exclude the check
+			if excluded.Has(check.Name()) {
+				excluded.Delete(check.Name())
+				fmt.Fprintf(&verboseOut, "[+]%v excluded: ok\n", check.Name())
+				continue
+			}
+			if err := check.Check(r); err != nil {
+				// don't include the error since this endpoint is public.  If someone wants more detail
+				// they should have explicit permission to the detailed checks.
+				log.V(4).Info(fmt.Sprintf("healthz check %v failed: %v", check.Name(), err))
+				fmt.Fprintf(&verboseOut, "[-]%v failed: reason withheld\n", check.Name())
+				failed = true
+			} else {
+				fmt.Fprintf(&verboseOut, "[+]%v ok\n", check.Name())
+			}
+		}
+		if excluded.Len() > 0 {
+			fmt.Fprintf(&verboseOut, "warn: some health checks cannot be excluded: no matches for %v\n", formatQuoted(excluded.List()...))
+			log.Info(fmt.Sprintf("cannot exclude some health checks, no health checks are installed matching %v",
+				formatQuoted(excluded.List()...)))
+		}
+		// always be verbose on failure
+		if failed {
+			log.V(2).Info(fmt.Sprintf("%vhealthz check failed", verboseOut.String()))
+			http.Error(w, fmt.Sprintf("%vhealthz check failed", verboseOut.String()), http.StatusInternalServerError)
+			return
+		}
+
+		w.Header().Set("Content-Type", "text/plain; charset=utf-8")
+		w.Header().Set("X-Content-Type-Options", "nosniff")
+		if _, found := r.URL.Query()["verbose"]; !found {
+			fmt.Fprint(w, "ok")
+			return
+		}
+
+		_, err := verboseOut.WriteTo(w)
+		if err != nil {
+			log.V(2).Info(fmt.Sprintf("%vhealthz check failed", verboseOut.String()))
+			http.Error(w, fmt.Sprintf("%vhealthz check failed", verboseOut.String()), http.StatusInternalServerError)
+			return
+		}
+		fmt.Fprint(w, "healthz check passed\n")
+	})
+}
+
+// adaptCheckToHandler returns an http.HandlerFunc that serves the provided checks.
+func adaptCheckToHandler(c func(r *http.Request) error) http.HandlerFunc {
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		err := c(r)
+		if err != nil {
+			http.Error(w, fmt.Sprintf("internal server error: %v", err), http.StatusInternalServerError)
+		} else {
+			fmt.Fprint(w, "ok")
+		}
+	})
+}
+
+// checkerNames returns the names of the checks in the same order as passed in.
+func checkerNames(checks ...Checker) []string {
+	// accumulate the names of checks for printing them out.
+	checkerNames := make([]string, 0, len(checks))
+	for _, check := range checks {
+		checkerNames = append(checkerNames, check.Name())
+	}
+	return checkerNames
+}
+
+// formatQuoted returns a formatted string of the health check names,
+// preserving the order passed in.
+func formatQuoted(names ...string) string {
+	quoted := make([]string, 0, len(names))
+	for _, name := range names {
+		quoted = append(quoted, fmt.Sprintf("%q", name))
+	}
+	return strings.Join(quoted, ",")
+}