devenv: slow_proxy_mac: make configurable and smaller (#34560)

devenv/docker/blocks/slow_proxy_mac/.env

@@ -0,0 +1,2 @@
+ORIGIN_SERVER=http://host.docker.internal:9090/
+SLEEP_DURATION=60s

devenv/docker/blocks/slow_proxy_mac/Dockerfile

@@ -1,7 +1,10 @@
-
+FROM golang:latest as builder
-FROM golang:latest
 ADD main.go /
 WORKDIR /
-RUN GO111MODULE=off go build -o main .
+RUN GO111MODULE=off CGO_ENABLED=0 go build -o main .
+
+FROM scratch
+WORKDIR /
 EXPOSE 3011
+COPY --from=builder /main /main
 ENTRYPOINT ["/main"]

devenv/docker/blocks/slow_proxy_mac/docker-compose.yaml

@@ -3,4 +3,5 @@
     ports:
       - '3011:3011'
     environment:
-      ORIGIN_SERVER: 'http://host.docker.internal:9090/'
+      ORIGIN_SERVER: ${ORIGIN_SERVER}
+      SLEEP_DURATION: ${SLEEP_DURATION}

devenv/docker/blocks/slow_proxy_mac/main.go

@@ -1,7 +1,6 @@
 package main
 
 import (
-	"fmt"
 	"log"
 	"net/http"
 	"net/http/httputil"
@@ -13,16 +12,26 @@ import (
 func main() {
 	origin := os.Getenv("ORIGIN_SERVER")
 	if origin == "" {
-		origin = "http://host.docker.internal:9090/"
+		// it is never not-set, the default is in the `.env` file
+		log.Fatalf("missing env-variable ORIGIN_SERVER")
 	}
 
-	sleep := time.Minute
+	sleepDurationStr := os.Getenv("SLEEP_DURATION")
+	if sleepDurationStr == "" {
+		// it is never not-set, the default is in the `.env` file
+		log.Fatalf("missing env-variable SLEEP_DURATION")
+	}
+
+	sleep, err := time.ParseDuration(sleepDurationStr)
+	if err != nil {
+		log.Fatalf("failed to parse SLEEP_DURATION: %v", err)
+	}
 
 	originURL, _ := url.Parse(origin)
 	proxy := httputil.NewSingleHostReverseProxy(originURL)
 
 	http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
-		fmt.Printf("sleeping for %s then proxying request: %s", sleep.String(), r.RequestURI)
+		log.Printf("sleeping for %s then proxying request: url '%s', headers: '%v'", sleep.String(), r.RequestURI, r.Header)
 		<-time.After(sleep)
 		proxy.ServeHTTP(w, r)
 	})