Use env for config instead of flags

.env

@@ -0,0 +1,2 @@
+LISTEN=:8080
+REDIS=:6379

Dockerfile

@@ -3,12 +3,13 @@ FROM golang:1.11-rc-alpine as build
 RUN apk add --no-cache git=2.18.1-r0
 
 WORKDIR /src
-COPY go.mod go.sum *.go ./
+COPY go.mod go.sum .env *.go ./
 RUN go get -d -v ./...
 RUN CGO_ENABLED=0 go build -ldflags "-s -w"
 
 FROM scratch
 
 COPY --from=build /src/heartbeat /heartbeat
+COPY --from=build /src/.env /.env
 
 ENTRYPOINT ["/heartbeat"]

README.md

@@ -2,14 +2,14 @@
 
 Beep backend records and makes available the last seen times of users.
 
-## Flags
+## Environment variables
 
-Flags are supplied to the compiled go program in the form ```-flag=stuff```.
+Supply environment variables by either exporting them or editing ```.env```.
 
-| Flag | Description | Default |
+| ENV | Description | Default |
 | ---- | ----------- | ------- |
-| listen | Port number to listen on | 8080 |
-| redis | Host and port of redis | :6379 |
+| LISTEN | Host and port number to listen on | :8080 |
+| REDIS | Host and port of redis | :6379 |
 
 ## API
 

go.mod

@@ -2,6 +2,7 @@ module heartbeat
 
 require (
 	github.com/go-redis/redis v6.15.1+incompatible
+	github.com/joho/godotenv v1.3.0
 	github.com/julienschmidt/httprouter v1.2.0
 	github.com/onsi/ginkgo v1.7.0 // indirect
 	github.com/onsi/gomega v1.4.3 // indirect

go.sum

@@ -6,6 +6,8 @@ github.com/golang/protobuf v1.2.0 h1:P3YflyNX/ehuJFLhxviNdFxQPkGK5cDcApsge1SqnvM
 github.com/golang/protobuf v1.2.0/go.mod h1:6lQm79b+lXiMfvg/cZm0SGofjICqVBUtrP5yJMmIC1U=
 github.com/hpcloud/tail v1.0.0 h1:nfCOvKYfkgYP8hkirhJocXT2+zOD8yUNjXaWfTlyFKI=
 github.com/hpcloud/tail v1.0.0/go.mod h1:ab1qPbhIpdTxEkNHXyeSf5vhxWSCs/tWer42PpOxQnU=
+github.com/joho/godotenv v1.3.0 h1:Zjp+RcGpHhGlrMbJzXTrZZPrWj+1vfm90La1wgB6Bhc=
+github.com/joho/godotenv v1.3.0/go.mod h1:7hK45KPybAkOC6peb+G5yklZfMxEjkZhHbwpqxOKXbg=
 github.com/julienschmidt/httprouter v1.2.0 h1:TDTW5Yz1mjftljbcKqRcrYhd4XeOoI98t+9HbQbYf7g=
 github.com/julienschmidt/httprouter v1.2.0/go.mod h1:SYymIcj16QtmaHHD7aYtjjsJG7VTCxuUUipMqKk8s4w=
 github.com/onsi/ginkgo v1.6.0/go.mod h1:lLunBs/Ym6LB5Z9jYTR76FiuTmxDTDusOGeTQH+WWjE=

main.go

@@ -1,13 +1,14 @@
 package main
 
 import (
-  "flag"
   "fmt"
   "log"
   "net/http"
+  "os"
   "strconv"
   "time"
 
+  "github.com/joho/godotenv"
   "github.com/julienschmidt/httprouter"
   "github.com/go-redis/redis"
 )
@@ -24,10 +25,13 @@ var connections map[RawClient][]chan []byte
 var redisClient *redis.Client
 
 func main() {
-  // Parse flags
-  flag.StringVar(&listen, "listen", ":8080", "host and port to listen on")
-  flag.StringVar(&redisHost, "redis", ":6379", "host and port of redis")
-  flag.Parse()
+  // Load .env
+  err := godotenv.Load()
+  if err != nil {
+    log.Fatal("Error loading .env file")
+  }
+  listen = os.Getenv("LISTEN")
+  redisHost = os.Getenv("REDIS")
 
   connections = make(map[RawClient][]chan []byte)