summaryrefslogtreecommitdiff
path: root/sd_daemon/watchdog.go
diff options
context:
space:
mode:
authorLuke Shumaker <lukeshu@sbcglobal.net>2016-12-18 03:20:47 -0500
committerLuke Shumaker <lukeshu@sbcglobal.net>2016-12-18 03:20:47 -0500
commit3b1bdfbd2687e81bef85260f9cdfbf617ece3527 (patch)
tree93f2c45e6e616ab63e5fb21f4d2a740d8b9b05e2 /sd_daemon/watchdog.go
parenteb6e8a6ca87879a6ca85788fcf6d3bf8848088e6 (diff)
Implement almost all of sd-daemon. BREAKING CHANGES.v0.2.0
This does not include the sd_is_* utility functions. BREAKING CHANGES: - The import name is now "sd_daemon" instead of "sd". - The logger interface is now entirely different. - Notify now takes more arguments.
Diffstat (limited to 'sd_daemon/watchdog.go')
-rw-r--r--sd_daemon/watchdog.go68
1 files changed, 68 insertions, 0 deletions
diff --git a/sd_daemon/watchdog.go b/sd_daemon/watchdog.go
new file mode 100644
index 0000000..b32f470
--- /dev/null
+++ b/sd_daemon/watchdog.go
@@ -0,0 +1,68 @@
+// Copyright 2016 CoreOS, Inc.
+// Copyright 2016 Luke Shumaker
+//
+// 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 sd_daemon
+
+import (
+ "os"
+ "strconv"
+ "time"
+)
+
+// WatchdogEnabled returns how often the process is expected to send a
+// keep-alive notification to the service manager.
+//
+// Notify(0, false, "WATCHDOG=1", nil) // send keep-alive notification
+//
+// If unsetEnv is true, then (regardless of whether the function call
+// itself succeeds or not) it will unset the environmental variables
+// WATCHDOG_USEC and WATCHDOG_PID, which will cause further calls to
+// this function to fail.
+//
+// If an error is returned, then the duration is 0. If the service
+// manager is not expecting a keep-alive notification from this
+// process (or if this has already been called with unsetEnv=true),
+// then ErrDisabled is returned. If there is an error parsing the
+// service manager's watchdog request, then an appropriate other error
+// is returned.
+func WatchdogEnabled(unsetEnv bool) (time.Duration, error) {
+ if unsetEnv {
+ defer func() {
+ _ = os.Unsetenv("WATCHDOG_USEC")
+ _ = os.Unsetenv("WATCHDOG_PID")
+ }()
+ }
+
+ usecStr, haveUsec := os.LookupEnv("WATCHDOG_USEC")
+ if !haveUsec {
+ return 0, ErrDisabled
+ }
+ usec, err := strconv.ParseInt(usecStr, 10, 64)
+ if err != nil || usec < 0 {
+ return 0, err
+ }
+
+ if pidStr, havePid := os.LookupEnv("WATCHDOG_PID"); havePid {
+ pid, err := strconv.Atoi(pidStr)
+ if err != nil {
+ return 0, err
+ }
+ if pid != os.Getpid() {
+ return 0, ErrDisabled
+ }
+ }
+
+ return time.Duration(usec) * time.Microsecond, nil
+}