Adds graceful shutdown for golang -middleware and -http

Closes: #35 Tested outside of a container, using kill -s TERM <PID> - it worked as expected by waiting for N seconds. Signed-off-by: Alex Ellis (OpenFaaS Ltd) <alexellis2@gmail.com>
openfaas · Feb 6, 2020 · 1c52628 · 1c52628
1 parent 23db8b3
commit 1c52628
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Showing 12 changed files with 256 additions and 68 deletions.
diff --git a/template/golang-http-armhf/.gitignore b/template/golang-http-armhf/.gitignore
@@ -0,0 +1 @@
+/handler
diff --git a/template/golang-http-armhf/Dockerfile b/template/golang-http-armhf/Dockerfile
@@ -1,4 +1,4 @@
-FROM openfaas/of-watchdog:0.7.3 as watchdog
+FROM openfaas/of-watchdog:0.7.6 as watchdog
 FROM golang:1.13-alpine3.11 as build
 
 RUN apk --no-cache add git

diff --git a/template/golang-http-armhf/main.go b/template/golang-http-armhf/main.go
@@ -1,19 +1,80 @@
 package main
 
 import (
+	"context"
 	"fmt"
 	"io/ioutil"
 	"log"
 	"net/http"
 	"os"
+	"os/signal"
 	"strconv"
+	"sync/atomic"
+	"syscall"
 	"time"
 
 	"handler/function"
-	// "github.com/alexellis/golang-http-template/template/golang-http/function"
+
 	handler "github.com/openfaas-incubator/go-function-sdk"
 )
 
+var (
+	acceptingConnections int32
+)
+
+const defaultTimeout = 10 * time.Second
+
+func main() {
+	readTimeout := parseIntOrDurationValue(os.Getenv("read_timeout"), defaultTimeout)
+	writeTimeout := parseIntOrDurationValue(os.Getenv("write_timeout"), defaultTimeout)
+
+	s := &http.Server{
+		Addr:           fmt.Sprintf(":%d", 8082),
+		ReadTimeout:    readTimeout,
+		WriteTimeout:   writeTimeout,
+		MaxHeaderBytes: 1 << 20, // Max header of 1MB
+	}
+
+	http.HandleFunc("/", makeRequestHandler())
+	listenUntilShutdown(s, writeTimeout)
+}
+
+func listenUntilShutdown(s *http.Server, shutdownTimeout time.Duration) {
+	idleConnsClosed := make(chan struct{})
+	go func() {
+		sig := make(chan os.Signal, 1)
+		signal.Notify(sig, syscall.SIGTERM)
+
+		<-sig
+
+		log.Printf("[entrypoint] SIGTERM received.. shutting down server in %s\n", shutdownTimeout.String())
+
+		<-time.Tick(shutdownTimeout)
+
+		if err := s.Shutdown(context.Background()); err != nil {
+			log.Printf("[entrypoint] Error in Shutdown: %v", err)
+		}
+
+		log.Printf("[entrypoint] No new connections allowed. Exiting in: %s\n", shutdownTimeout.String())
+
+		<-time.Tick(shutdownTimeout)
+
+		close(idleConnsClosed)
+	}()
+
+	// Run the HTTP server in a separate go-routine.
+	go func() {
+		if err := s.ListenAndServe(); err != http.ErrServerClosed {
+			log.Printf("[entrypoint] Error ListenAndServe: %v", err)
+			close(idleConnsClosed)
+		}
+	}()
+
+	atomic.StoreInt32(&acceptingConnections, 1)
+
+	<-idleConnsClosed
+}
+
 func makeRequestHandler() func(http.ResponseWriter, *http.Request) {
 	return func(w http.ResponseWriter, r *http.Request) {
 		var input []byte
@@ -74,18 +135,3 @@ func parseIntOrDurationValue(val string, fallback time.Duration) time.Duration {
 	}
 	return duration
 }
-
-func main() {
-	readTimeout := parseIntOrDurationValue(os.Getenv("read_timeout"), 10*time.Second)
-	writeTimeout := parseIntOrDurationValue(os.Getenv("write_timeout"), 10*time.Second)
-
-	s := &http.Server{
-		Addr:           fmt.Sprintf(":%d", 8082),
-		ReadTimeout:    readTimeout,
-		WriteTimeout:   writeTimeout,
-		MaxHeaderBytes: 1 << 20, // Max header of 1MB
-	}
-
-	http.HandleFunc("/", makeRequestHandler())
-	log.Fatal(s.ListenAndServe())
-}
diff --git a/template/golang-http/.gitignore b/template/golang-http/.gitignore
@@ -0,0 +1 @@
+/handler
diff --git a/template/golang-http/Dockerfile b/template/golang-http/Dockerfile
@@ -1,4 +1,4 @@
-FROM openfaas/of-watchdog:0.7.3 as watchdog
+FROM openfaas/of-watchdog:0.7.6 as watchdog
 FROM golang:1.13-alpine3.11 as build
 
 RUN apk --no-cache add git

diff --git a/template/golang-http/main.go b/template/golang-http/main.go
@@ -1,19 +1,80 @@
 package main
 
 import (
+	"context"
 	"fmt"
 	"io/ioutil"
 	"log"
 	"net/http"
 	"os"
+	"os/signal"
 	"strconv"
+	"sync/atomic"
+	"syscall"
 	"time"
 
 	"handler/function"
-	// "github.com/alexellis/golang-http-template/template/golang-http/function"
+
 	handler "github.com/openfaas-incubator/go-function-sdk"
 )
 
+var (
+	acceptingConnections int32
+)
+
+const defaultTimeout = 10 * time.Second
+
+func main() {
+	readTimeout := parseIntOrDurationValue(os.Getenv("read_timeout"), defaultTimeout)
+	writeTimeout := parseIntOrDurationValue(os.Getenv("write_timeout"), defaultTimeout)
+
+	s := &http.Server{
+		Addr:           fmt.Sprintf(":%d", 8082),
+		ReadTimeout:    readTimeout,
+		WriteTimeout:   writeTimeout,
+		MaxHeaderBytes: 1 << 20, // Max header of 1MB
+	}
+
+	http.HandleFunc("/", makeRequestHandler())
+	listenUntilShutdown(s, writeTimeout)
+}
+
+func listenUntilShutdown(s *http.Server, shutdownTimeout time.Duration) {
+	idleConnsClosed := make(chan struct{})
+	go func() {
+		sig := make(chan os.Signal, 1)
+		signal.Notify(sig, syscall.SIGTERM)
+
+		<-sig
+
+		log.Printf("[entrypoint] SIGTERM received.. shutting down server in %s\n", shutdownTimeout.String())
+
+		<-time.Tick(shutdownTimeout)
+
+		if err := s.Shutdown(context.Background()); err != nil {
+			log.Printf("[entrypoint] Error in Shutdown: %v", err)
+		}
+
+		log.Printf("[entrypoint] No new connections allowed. Exiting in: %s\n", shutdownTimeout.String())
+
+		<-time.Tick(shutdownTimeout)
+
+		close(idleConnsClosed)
+	}()
+
+	// Run the HTTP server in a separate go-routine.
+	go func() {
+		if err := s.ListenAndServe(); err != http.ErrServerClosed {
+			log.Printf("[entrypoint] Error ListenAndServe: %v", err)
+			close(idleConnsClosed)
+		}
+	}()
+
+	atomic.StoreInt32(&acceptingConnections, 1)
+
+	<-idleConnsClosed
+}
+
 func makeRequestHandler() func(http.ResponseWriter, *http.Request) {
 	return func(w http.ResponseWriter, r *http.Request) {
 		var input []byte
@@ -74,18 +135,3 @@ func parseIntOrDurationValue(val string, fallback time.Duration) time.Duration {
 	}
 	return duration
 }
-
-func main() {
-	readTimeout := parseIntOrDurationValue(os.Getenv("read_timeout"), 10*time.Second)
-	writeTimeout := parseIntOrDurationValue(os.Getenv("write_timeout"), 10*time.Second)
-
-	s := &http.Server{
-		Addr:           fmt.Sprintf(":%d", 8082),
-		ReadTimeout:    readTimeout,
-		WriteTimeout:   writeTimeout,
-		MaxHeaderBytes: 1 << 20, // Max header of 1MB
-	}
-
-	http.HandleFunc("/", makeRequestHandler())
-	log.Fatal(s.ListenAndServe())
-}
diff --git a/template/golang-middleware-armhf/.gitignore b/template/golang-middleware-armhf/.gitignore
@@ -0,0 +1 @@
+/handler
diff --git a/template/golang-middleware-armhf/Dockerfile b/template/golang-middleware-armhf/Dockerfile
@@ -1,4 +1,4 @@
-FROM openfaas/of-watchdog:0.7.3 as watchdog
+FROM openfaas/of-watchdog:0.7.6 as watchdog
 FROM golang:1.13-alpine3.11 as build
 
 RUN apk --no-cache add git

diff --git a/template/golang-middleware-armhf/main.go b/template/golang-middleware-armhf/main.go
@@ -1,17 +1,78 @@
 package main
 
 import (
+	"context"
 	"fmt"
 	"log"
 	"net/http"
 	"os"
+	"os/signal"
 	"strconv"
+	"sync/atomic"
+	"syscall"
 	"time"
 
 	"handler/function"
-	//"github.com/openfaas-incubator/golang-http-template/template/golang-middleware/function"
 )
 
+var (
+	acceptingConnections int32
+)
+
+const defaultTimeout = 10 * time.Second
+
+func main() {
+	readTimeout := parseIntOrDurationValue(os.Getenv("read_timeout"), defaultTimeout)
+	writeTimeout := parseIntOrDurationValue(os.Getenv("write_timeout"), defaultTimeout)
+
+	s := &http.Server{
+		Addr:           fmt.Sprintf(":%d", 8082),
+		ReadTimeout:    readTimeout,
+		WriteTimeout:   writeTimeout,
+		MaxHeaderBytes: 1 << 20, // Max header of 1MB
+	}
+
+	http.HandleFunc("/", function.Handle)
+
+	listenUntilShutdown(s, writeTimeout)
+}
+
+func listenUntilShutdown(s *http.Server, shutdownTimeout time.Duration) {
+	idleConnsClosed := make(chan struct{})
+	go func() {
+		sig := make(chan os.Signal, 1)
+		signal.Notify(sig, syscall.SIGTERM)
+
+		<-sig
+
+		log.Printf("[entrypoint] SIGTERM received.. shutting down server in %s\n", shutdownTimeout.String())
+
+		<-time.Tick(shutdownTimeout)
+
+		if err := s.Shutdown(context.Background()); err != nil {
+			log.Printf("[entrypoint] Error in Shutdown: %v", err)
+		}
+
+		log.Printf("[entrypoint] No new connections allowed. Exiting in: %s\n", shutdownTimeout.String())
+
+		<-time.Tick(shutdownTimeout)
+
+		close(idleConnsClosed)
+	}()
+
+	// Run the HTTP server in a separate go-routine.
+	go func() {
+		if err := s.ListenAndServe(); err != http.ErrServerClosed {
+			log.Printf("[entrypoint] Error ListenAndServe: %v", err)
+			close(idleConnsClosed)
+		}
+	}()
+
+	atomic.StoreInt32(&acceptingConnections, 1)
+
+	<-idleConnsClosed
+}
+
 func parseIntOrDurationValue(val string, fallback time.Duration) time.Duration {
 	if len(val) > 0 {
 		parsedVal, parseErr := strconv.Atoi(val)
@@ -26,18 +87,3 @@ func parseIntOrDurationValue(val string, fallback time.Duration) time.Duration {
 	}
 	return duration
 }
-
-func main() {
-	readTimeout := parseIntOrDurationValue(os.Getenv("read_timeout"), 10*time.Second)
-	writeTimeout := parseIntOrDurationValue(os.Getenv("write_timeout"), 10*time.Second)
-
-	s := &http.Server{
-		Addr:           fmt.Sprintf(":%d", 8082),
-		ReadTimeout:    readTimeout,
-		WriteTimeout:   writeTimeout,
-		MaxHeaderBytes: 1 << 20, // Max header of 1MB
-	}
-
-	http.HandleFunc("/", function.Handle)
-	log.Fatal(s.ListenAndServe())
-}
diff --git a/template/golang-middleware/.gitignore b/template/golang-middleware/.gitignore
@@ -0,0 +1 @@
+/handler
diff --git a/template/golang-middleware/Dockerfile b/template/golang-middleware/Dockerfile
@@ -1,4 +1,4 @@
-FROM openfaas/of-watchdog:0.7.3 as watchdog
+FROM openfaas/of-watchdog:0.7.6 as watchdog
 FROM golang:1.13-alpine3.11 as build
 
 RUN apk --no-cache add git