Various improvements

.circleci/config.yml

@@ -18,7 +18,7 @@ jobs:
       - checkout
       - docker/build:
           image: pboehm/ddns
-          dockerfile: docker/ddns/Dockerfile
+          dockerfile: Dockerfile
 
   docker-build-and-push:
     executor: docker/docker
@@ -28,7 +28,7 @@ jobs:
       - docker/check
       - docker/build:
           image: pboehm/ddns
-          dockerfile: docker/ddns/Dockerfile
+          dockerfile: Dockerfile
           tag: $CIRCLE_SHA1,latest
       - docker/push:
           image: pboehm/ddns

.gitignore

@@ -2,5 +2,6 @@
 /docker/docker-compose.*.yml
 /ddns
 dump.rdb
+index.html
 /docker/.caddy_mount/
 /docker/.redis_mount/

Dockerfile

@@ -0,0 +1,17 @@
+FROM golang:alpine AS builder
+
+RUN apk add --no-cache git
+
+WORKDIR /go/src/github.com/pboehm/ddns
+COPY . .
+
+RUN GO111MODULE=on go get -d -v ./...
+RUN export CGO_ENABLED=0 && GO111MODULE=on go install -v ./...
+
+ENV GIN_MODE release
+
+FROM scratch
+
+COPY --from=builder /go/bin/ddns /go/bin/ddns
+
+ENTRYPOINT ["/go/bin/ddns"]

backend/backend.go

@@ -1,26 +1,36 @@
 package backend
 
 import (
+	"github.com/Depado/ginprom"
 	"github.com/gin-gonic/gin"
 	"github.com/pboehm/ddns/shared"
+	"github.com/prometheus/client_golang/prometheus"
 	"log"
 	"strings"
 )
 
 type Backend struct {
-	config *shared.Config
-	lookup *HostLookup
+	config   *shared.Config
+	lookup   *HostLookup
+	registry *prometheus.Registry
 }
 
-func NewBackend(config *shared.Config, lookup *HostLookup) *Backend {
+func NewBackend(config *shared.Config, lookup *HostLookup, registry *prometheus.Registry) *Backend {
 	return &Backend{
-		config: config,
-		lookup: lookup,
+		config:   config,
+		lookup:   lookup,
+		registry: registry,
 	}
 }
 
 func (b *Backend) Run() error {
+	prom := ginprom.New(ginprom.Namespace("ddns"),
+		ginprom.Subsystem("backend"), ginprom.Registry(b.registry))
+
 	r := gin.New()
+	r.Use(prom.Instrument())
+	prom.Use(r)
+
 	r.Use(gin.Recovery())
 
 	if b.config.Verbose {

ddns.go

@@ -4,6 +4,7 @@ import (
 	"github.com/pboehm/ddns/backend"
 	"github.com/pboehm/ddns/frontend"
 	"github.com/pboehm/ddns/shared"
+	"github.com/prometheus/client_golang/prometheus"
 	"golang.org/x/sync/errgroup"
 	"log"
 )
@@ -17,18 +18,24 @@ func init() {
 func main() {
 	serviceConfig.Validate()
 
+	if serviceConfig.Verbose {
+		log.Printf("Loaded config: %#v", serviceConfig)
+	}
+
 	redis := shared.NewRedisBackend(serviceConfig)
 	defer redis.Close()
 
+	registry := prometheus.NewRegistry()
+
 	var group errgroup.Group
 
 	group.Go(func() error {
 		lookup := backend.NewHostLookup(serviceConfig, redis)
-		return backend.NewBackend(serviceConfig, lookup).Run()
+		return backend.NewBackend(serviceConfig, lookup, registry).Run()
 	})
 
 	group.Go(func() error {
-		return frontend.NewFrontend(serviceConfig, redis).Run()
+		return frontend.NewFrontend(serviceConfig, redis, registry).Run()
 	})
 
 	if err := group.Wait(); err != nil {

docker/ddns/Dockerfile

@@ -14,5 +14,5 @@ ENV DDNS_EXPIRATION_DAYS 10
 CMD /go/bin/ddns \
     --domain=${DDNS_DOMAIN} \
     --soa_fqdn=${DDNS_SOA_DOMAIN} \
-    --redis=${DDNS_REDIS_HOST} \
+    --redis-host=${DDNS_REDIS_HOST} \
     --expiration-days=${DDNS_EXPIRATION_DAYS}

frontend/frontend.go

@@ -2,8 +2,10 @@ package frontend
 
 import (
 	"fmt"
+	"github.com/Depado/ginprom"
 	"github.com/gin-gonic/gin"
 	"github.com/pboehm/ddns/shared"
+	"github.com/prometheus/client_golang/prometheus"
 	"html/template"
 	"log"
 	"net"
@@ -12,26 +14,34 @@ import (
 )
 
 type Frontend struct {
-	config *shared.Config
-	hosts  shared.HostBackend
+	config   *shared.Config
+	hosts    shared.HostBackend
+	registry *prometheus.Registry
 }
 
-func NewFrontend(config *shared.Config, hosts shared.HostBackend) *Frontend {
+func NewFrontend(config *shared.Config, hosts shared.HostBackend, registry *prometheus.Registry) *Frontend {
 	return &Frontend{
-		config: config,
-		hosts:  hosts,
+		config:   config,
+		hosts:    hosts,
+		registry: registry,
 	}
 }
 
 func (f *Frontend) Run() error {
+	prom := ginprom.New(ginprom.Namespace("ddns"),
+		ginprom.Subsystem("frontend"), ginprom.Registry(f.registry))
+
 	r := gin.New()
+	r.Use(prom.Instrument())
+	prom.Engine = r // we don't want to expose the metrics on the frontend, so we are not using `prom.Use(r)`
+
 	r.Use(gin.Recovery())
 
 	if f.config.Verbose {
 		r.Use(gin.Logger())
 	}
 
-	r.SetHTMLTemplate(buildTemplate())
+	r.SetHTMLTemplate(buildTemplate(f.config.CustomTemplatePath))
 
 	r.GET("/", func(g *gin.Context) {
 		g.HTML(200, "index.html", gin.H{"domain": f.config.Domain})
@@ -143,10 +153,18 @@ func extractRemoteAddr(req *http.Request) (string, error) {
 }
 
 // Get index template from bindata
-func buildTemplate() *template.Template {
-	html, err := template.New("index.html").Parse(indexTemplate)
+func buildTemplate(customTemplatePath string) *template.Template {
+	var html *template.Template
+	var err error
+
+	if customTemplatePath != "" {
+		html, err = template.ParseFiles(customTemplatePath)
+	} else {
+		html, err = template.New("index.html").Parse(indexTemplate)
+	}
+
 	if err != nil {
-		log.Fatal(err)
+		log.Fatalf("Error parsing frontend template: %v", err)
 	}
 
 	return html

go.mod

@@ -3,8 +3,24 @@ module github.com/pboehm/ddns
 go 1.12
 
 require (
-	github.com/garyburd/redigo v1.6.0
-	github.com/gin-gonic/gin v1.4.0
-	github.com/stretchr/testify v1.3.0
-	golang.org/x/sync v0.0.0-20190423024810-112230192c58
+	github.com/Depado/ginprom v1.5.0
+	github.com/garyburd/redigo v1.6.2
+	github.com/gin-gonic/gin v1.6.3
+	github.com/go-playground/validator/v10 v10.4.1 // indirect
+	github.com/golang/protobuf v1.4.3 // indirect
+	github.com/jnovack/flag v1.15.0
+	github.com/json-iterator/go v1.1.10 // indirect
+	github.com/leodido/go-urn v1.2.1 // indirect
+	github.com/modern-go/concurrent v0.0.0-20180306012644-bacd9c7ef1dd // indirect
+	github.com/modern-go/reflect2 v1.0.1 // indirect
+	github.com/prometheus/client_golang v1.9.0
+	github.com/prometheus/common v0.17.0 // indirect
+	github.com/prometheus/procfs v0.6.0 // indirect
+	github.com/stretchr/testify v1.6.1
+	github.com/ugorji/go v1.2.4 // indirect
+	golang.org/x/crypto v0.0.0-20210220033148-5ea612d1eb83 // indirect
+	golang.org/x/sync v0.0.0-20210220032951-036812b2e83c
+	golang.org/x/sys v0.0.0-20210220050731-9a76102bfb43 // indirect
+	google.golang.org/protobuf v1.25.0 // indirect
+	gopkg.in/yaml.v2 v2.4.0 // indirect
 )