Clean up certmagic locks on signaled process exit

This should help prevent hanging in some cases when the process is
restarted and tries to obtain or renew a certificate, for example, but
the lock remains from the previous shutdown (which was during the same
operation). Only works if the process is cleanly shut down with a signal
it can capture.

go.mod

@@ -14,7 +14,7 @@ require (
 	github.com/klauspost/cpuid v1.2.0
 	github.com/kylelemons/godebug v0.0.0-20170820004349-d65d576e9348 // indirect
 	github.com/lucas-clemente/quic-go v0.10.2
-	github.com/mholt/certmagic v0.5.0
+	github.com/mholt/certmagic v0.6.1-0.20190619225040-c7a9fdb17816
 	github.com/naoina/go-stringutil v0.1.0 // indirect
 	github.com/naoina/toml v0.1.1
 	github.com/russross/blackfriday v0.0.0-20170610170232-067529f716f4

go.sum

@@ -44,8 +44,8 @@ github.com/lucas-clemente/quic-go v0.10.2/go.mod h1:hvaRS9IHjFLMq76puFJeWNfmn+H7
 github.com/lucas-clemente/quic-go-certificates v0.0.0-20160823095156-d2f86524cced h1:zqEC1GJZFbGZA0tRyNZqRjep92K5fujFtFsu5ZW7Aug=
 github.com/lucas-clemente/quic-go-certificates v0.0.0-20160823095156-d2f86524cced/go.mod h1:NCcRLrOTZbzhZvixZLlERbJtDtYsmMw8Jc4vS8Z0g58=
 github.com/marten-seemann/qtls v0.2.3/go.mod h1:xzjG7avBwGGbdZ8dTGxlBnLArsVKLvwmjgmPuiQEcYk=
-github.com/mholt/certmagic v0.5.0 h1:lYXxsLUFya/I3BgDCrfuwcMQOB+4auzI8CCzpK41tjc=
-github.com/mholt/certmagic v0.5.0/go.mod h1:g4cOPxcjV0oFq3qwpjSA30LReKD8AoIfwAY9VvG35NY=
+github.com/mholt/certmagic v0.6.1-0.20190619225040-c7a9fdb17816 h1:DEoTKH/n8k9JXYqM/A3AmW407Q5Rncrkuipqu0mztcg=
+github.com/mholt/certmagic v0.6.1-0.20190619225040-c7a9fdb17816/go.mod h1:g4cOPxcjV0oFq3qwpjSA30LReKD8AoIfwAY9VvG35NY=
 github.com/miekg/dns v1.1.3 h1:1g0r1IvskvgL8rR+AcHzUA+oFmGcQlaIm4IqakufeMM=
 github.com/miekg/dns v1.1.3/go.mod h1:W1PPwlIAgtquWBMBEV9nkV9Cazfe8ScdGz/Lj7v3Nrg=
 github.com/naoina/go-stringutil v0.1.0 h1:rCUeRUHjBjGTSHl0VC00jUPLz8/F9dDzYI70Hzifhks=

sigtrap.go

@@ -21,6 +21,7 @@ import (
 	"sync"
 
 	"github.com/mholt/caddy/telemetry"
+	"github.com/mholt/certmagic"
 )
 
 // TrapSignals create signal handlers for all applicable signals for this
@@ -49,6 +50,7 @@ func trapSignalsCrossPlatform() {
 				for _, f := range OnProcessExit {
 					f() // important cleanup actions only
 				}
+				certmagic.CleanUpOwnLocks()
 				os.Exit(2)
 			}
 
@@ -63,6 +65,7 @@ func trapSignalsCrossPlatform() {
 			}
 
 			go func() {
+				certmagic.CleanUpOwnLocks()
 				os.Exit(executeShutdownCallbacks("SIGINT"))
 			}()
 		}

sigtrap_posix.go

@@ -23,6 +23,7 @@ import (
 	"syscall"
 
 	"github.com/mholt/caddy/telemetry"
+	"github.com/mholt/certmagic"
 )
 
 // trapSignalsPosix captures POSIX-only signals.
@@ -38,6 +39,7 @@ func trapSignalsPosix() {
 				for _, f := range OnProcessExit {
 					f() // only perform important cleanup actions
 				}
+				certmagic.CleanUpOwnLocks()
 				os.Exit(0)
 
 			case syscall.SIGTERM:
@@ -55,6 +57,7 @@ func trapSignalsPosix() {
 				telemetry.AppendUnique("sigtrap", "SIGTERM")
 				go telemetry.StopEmitting() // won't finish in time, but that's OK - just don't block
 
+				certmagic.CleanUpOwnLocks()
 				os.Exit(exitCode)
 
 			case syscall.SIGUSR1: