feat: add a health check handler (#121)

Author: agneum

Makefile

@@ -4,7 +4,7 @@ SERVER_BINARY = dblab-server
 CLI_BINARY = dblab
 GOARCH = amd64
 
-VERSION?=0.1
+VERSION?=0.3.1
 BUILD_TIME?=$(shell date -u '+%Y%m%d-%H%M')
 COMMIT?=no #$(shell git rev-parse HEAD)
 BRANCH?=no #$(shell git rev-parse --abbrev-ref HEAD)
@@ -14,10 +14,10 @@ BUILD_DIR=${GOPATH}/${SERVER_BINARY}
 
 # Setup the -ldflags option for go build here, interpolate the variable values
 LDFLAGS = -ldflags "-s -w \
-	-X main.version=${VERSION} \
+	-X gitlab.com/postgres-ai/database-lab/version.version=${VERSION} \
 	-X main.commit=${COMMIT} \
 	-X main.branch=${BRANCH}\
-	-X main.buildTime=${BUILD_TIME}"
+	-X gitlab.com/postgres-ai/database-lab/version.buildTime=${BUILD_TIME}"
 
 # Go tooling command aliases
 GOBUILD = GO111MODULE=on GOARCH=${GOARCH} go build ${LDFLAGS}

cmd/cli/main.go

@@ -16,15 +16,12 @@ import (
 	"gitlab.com/postgres-ai/database-lab/cmd/cli/commands/snapshot"
 	"gitlab.com/postgres-ai/database-lab/cmd/cli/templates"
 	dblabLog "gitlab.com/postgres-ai/database-lab/pkg/log"
-)
-
-const (
-	version = "v0.2.3"
+	"gitlab.com/postgres-ai/database-lab/version"
 )
 
 func main() {
 	app := &cli.App{
-		Version: version,
+		Version: version.GetVersion(),
 		CommandNotFound: func(c *cli.Context, command string) {
 			fmt.Fprintf(c.App.Writer, "[ERROR] Command %q not found.\n", command)
 		},

pkg/srv/routes.go

@@ -1,6 +1,7 @@
 package srv
 
 import (
+	"encoding/json"
 	"fmt"
 	"net/http"
 
@@ -9,8 +10,14 @@ import (
 
 	"gitlab.com/postgres-ai/database-lab/pkg/client/dblabapi/types"
 	"gitlab.com/postgres-ai/database-lab/pkg/log"
+	"gitlab.com/postgres-ai/database-lab/version"
 )
 
+// HealthResponse represents a response for heath-check requests.
+type HealthResponse struct {
+	Version string `json:"version"`
+}
+
 func (s *Server) getInstanceStatus() http.HandlerFunc {
 	return func(w http.ResponseWriter, r *http.Request) {
 		status, err := s.Cloning.GetInstanceState()
@@ -136,3 +143,19 @@ func (s *Server) resetClone() http.HandlerFunc {
 		log.Dbg(fmt.Sprintf("Clone ID=%s is being reset", cloneID))
 	}
 }
+
+// healthCheck provides a health check handler.
+func (s *Server) healthCheck(w http.ResponseWriter, _ *http.Request) {
+	w.Header().Set("Content-Type", "application/json; charset=utf-8")
+
+	healthResponse := HealthResponse{
+		Version: version.GetVersion(),
+	}
+
+	if err := json.NewEncoder(w).Encode(healthResponse); err != nil {
+		http.Error(w, err.Error(), http.StatusInternalServerError)
+		log.Err(err)
+
+		return
+	}
+}

pkg/srv/server.go

@@ -92,6 +92,9 @@ func (s *Server) Run() error {
 	r.HandleFunc("/clone/{id}/reset",
 		authMW.authorized(s.resetClone())).Methods(http.MethodPost)
 
+	// Health check.
+	r.HandleFunc("/healthz", s.healthCheck).Methods(http.MethodGet)
+
 	// Show Swagger UI on index page.
 	if err := attachAPI(r); err != nil {
 		log.Err(fmt.Sprintf("Cannot load API description."))

version/version.go

@@ -0,0 +1,21 @@
+/*
+2019 © Postgres.ai
+*/
+
+// Package version provides the Database Lab version info.
+package version
+
+import (
+	"fmt"
+)
+
+// ldflag variables.
+var (
+	version   string
+	buildTime string
+)
+
+// GetVersion return the app version info.
+func GetVersion() string {
+	return fmt.Sprintf("%s-%s", version, buildTime)
+}

version/version_test.go

@@ -0,0 +1,18 @@
+/*
+2019 © Postgres.ai
+*/
+
+package version
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestGetVersion(t *testing.T) {
+	version = "0.0.1"
+	buildTime = "20200427-0551"
+
+	assert.Equal(t, "0.0.1-20200427-0551", GetVersion())
+}