diff options
| -rw-r--r-- | .gitignore | 2 | ||||
| -rw-r--r-- | Dockerfile | 6 | ||||
| -rw-r--r-- | README.md | 28 | ||||
| -rw-r--r-- | main.go | 58 |
4 files changed, 67 insertions, 27 deletions
@@ -1,2 +1,4 @@ tags showreadiness + +.vscode/
\ No newline at end of file @@ -1,6 +1,6 @@ -FROM busybox:latest +FROM scratch LABEL maintainer="Tyler Davis <tydavis@gmail.com>" EXPOSE 80 -COPY showreadiness / -CMD /showreadiness +COPY showreadiness . +CMD ["./showreadiness"] @@ -1,17 +1,35 @@ # showReadiness -A simple golang application to explore [liveness and readiness checks](http://kubernetes.io/docs/user-guide/pod-states/) in Kubernetes. +A simple golang application to explore [liveness and readiness checks][1] in +Kubernetes. ## To build + In the cloned directory, run the following: -``` + +Linux/OSX: + +```bash CGO_ENABLED=0 GOOS=linux GOARCH=amd64 go build -a -tags netgo -installsuffix netgo -ldflags '-w -s' . ``` -## To build with only Docker -Ensure [docker](https://www.docker.com/get-docker) is installed. In the cloned directory, run the folowing: +Windows: +```powershell +$env:CGO_ENABLED=0; $env:GOOS="linux"; $env:GOARCH="amd64"; go build -a -tags netgo -installsuffix netgo -ldflags "-s" ``` -docker run --rm -v $PWD:/go/src/github.com/tydavis/showreadiness -w /go/src/github.com/tydavis/showreadiness golang:alpine /bin/sh -c "CGO_ENABLED=0 GOOS=linux GOARCH=amd64 go build -a -tags netgo -installsuffix netgo -ldflags '-w -s' . " + +Or type your + +## To build with only Docker + +If [docker][2] is installed, run the folowing in the checked-out directory: + +```bash +docker run --rm -v $PWD:/go/src/github.com/tydavis/showreadiness \ +-w /go/src/github.com/tydavis/showreadiness golang:alpine /bin/sh \ +-c "CGO_ENABLED=0 GOOS=linux GOARCH=amd64 go build -a -tags netgo -installsuffix netgo -ldflags '-w -s' . " ``` +[1]:http://kubernetes.io/docs/user-guide/pod-states/ +[2]:https://www.docker.com/get-docker
\ No newline at end of file @@ -5,46 +5,73 @@ import ( "log" "net/http" "os" + "sync" "time" ) +// Globals are generally discouraged, but this is a very simple program, and we +// are designing with concurrent access in mind. + +// Creating a custom struct with a lock, so we can lock access to the object +type status struct { + value int + sync.Mutex +} + // ReadyValue indiciates the program is ready to receive traffic -var ReadyValue = http.StatusOK +var ReadyValue = status{value: http.StatusOK} // LiveValue indiciates the program is alive and should not be terminated -var LiveValue = http.StatusOK +var LiveValue = status{value: http.StatusOK} var hostname string func makeNotReady(w http.ResponseWriter, r *http.Request) { - ReadyValue = http.StatusBadRequest + // Lock access to the variable, then set our global ReadyValue to a failing + // value before sending the response + ReadyValue.Lock() + ReadyValue.value = http.StatusBadRequest + ReadyValue.Unlock() w.Header().Set("responding-pod", hostname) fmt.Fprintf(w, "%s", "Set Readiness Value to a failure state") } +// Hitting this endpoint (by any means) will func makePodReady(w http.ResponseWriter, r *http.Request) { - ReadyValue = http.StatusOK + ReadyValue.Lock() + ReadyValue.value = http.StatusOK + ReadyValue.Unlock() w.Header().Set("responding-pod", hostname) fmt.Fprintf(w, "%s", "Set Readiness Value to successful (OK) state") } +// This function guarantees Kubernetes will kill the pod func killMe(w http.ResponseWriter, r *http.Request) { - LiveValue = http.StatusBadRequest + LiveValue.Lock() + LiveValue.value = http.StatusBadRequest + LiveValue.Unlock() w.Header().Set("responding-pod", hostname) fmt.Fprintf(w, "%s", "Set Liveness Value to a failure state") } +// Provides Ready state to Kubernetes for receiving/stopping traffic func readinessCheck(w http.ResponseWriter, r *http.Request) { w.Header().Set("responding-pod", hostname) - http.Error(w, "Responding with ReadyValue", ReadyValue) + ReadyValue.Lock() + http.Error(w, "Responding with ReadyValue", ReadyValue.value) + ReadyValue.Unlock() } +// Endpoint checked internally by Kubernetes func livenessCheck(w http.ResponseWriter, r *http.Request) { w.Header().Set("responding-pod", hostname) - http.Error(w, "Responding with LiveValue", LiveValue) + LiveValue.Lock() + http.Error(w, "Responding with LiveValue", LiveValue.value) + LiveValue.Unlock() } +// The default endpoint func rootHandler(w http.ResponseWriter, r *http.Request) { w.Header().Set("responding-pod", hostname) fmt.Fprintf(w, "%s", "I'm serving traffic!") @@ -54,21 +81,14 @@ func main() { // Force log output to stdout for Docker log.SetOutput(os.Stdout) - // Configurable delay for startup - var delay = (1 * time.Second) - if os.Getenv("APPDELAY") != "" { - var err error - delay, err = time.ParseDuration(os.Getenv("APPDELAY")) - if err != nil { - log.Fatalf("Failed to parse time duration: %v", err) - } - } - time.Sleep(delay) - // Finish startup hostname, _ = os.Hostname() log.Println("Service started on port 80") + // Set up a custom mutex to add custom handlers. [Note] this level of breakout + // is not required, as we could reasonably compact this into a single call, + // but would lose some readability. This also makes it easy for us to use a + // custom muxer (e.g. gorillamux), custom server, etc mux := http.NewServeMux() mux.HandleFunc("/", rootHandler) mux.HandleFunc("/ping", livenessCheck) @@ -84,8 +104,8 @@ func main() { WriteTimeout: 3 * time.Second, } + // Actually run our server if err := server.ListenAndServe(); err != nil { log.Fatalln(err) } - } |