Adding simple Traefik example. (docker#44)

Adding simple Traefik example.

Signed-off-by: lfache <61111030+lfache@users.noreply.github.com>

README.md

@@ -41,6 +41,7 @@ with Spring framework and a Postgres database.
 - [`VueJS`](https://github.com/docker/awesome-compose/tree/master/vuejs)
 - [`Flask`](https://github.com/docker/awesome-compose/tree/master/flask)
 - [`PHP`](https://github.com/docker/awesome-compose/tree/master/apache-php)
+- [`Traefik`](https://github.com/docker/awesome-compose/tree/master/traefik-golang)
 - [`Django`](https://github.com/docker/awesome-compose/tree/master/django)
 ## Basic setups for different platforms (not production ready - useful for personal use) 
 - [`Gitea / PostgreSQL`](https://github.com/docker/awesome-compose/tree/master/gitea-postgres)

traefik-golang/README.md

@@ -0,0 +1,97 @@
+## Compose sample application
+### TRAEFIK proxy with GO backend
+
+Project structure:
+```
+.
+├── backend
+│   ├── Dockerfile
+│   └── main.go
+├── docker-compose.yml
+└── README.md
+```
+
+[_docker-compose.yaml_](docker-compose.yaml)
+```
+version: "3.7"
+services:
+  frontend:
+    image: traefik:2.2
+    command: --providers.docker --entrypoints.web.address=:80 --providers.docker.exposedbydefault=false
+    ports:
+      # The HTTP port
+      - "80:80"
+    volumes:
+      # So that Traefik can listen to the Docker events
+      - /var/run/docker.sock:/var/run/docker.sock
+    depends_on:
+      - backend
+  backend:
+    build: backend
+    labels:
+      - "traefik.enable=true"
+      - "traefik.http.routers.go.rule=Path(`/`)"
+      - "traefik.http.services.go.loadbalancer.server.port=80"
+
+```
+The compose file defines an application with two services `frontend` and `backend`.
+When deploying the application, docker-compose maps port 80 of the frontend service container to the same port of the host as specified in the file.
+Make sure port 80 on the host is not already being in use.
+
+## Deploy with docker-compose
+
+```
+$ docker-compose up -d
+Creating network "traefik-golang_default" with the default driver
+Building backend
+Step 1/7 : FROM golang:1.13 AS build
+1.13: Pulling from library/golang
+...
+Successfully built 22397f6cd4bc
+Successfully tagged traefik-golang_backend:latest
+WARNING: Image for service backend was built because it did not already exist. To rebuild this image you must use `docker-compose build` or `docker-compose up --build`.
+Pulling frontend (traefik:2.2)...
+2.2: Pulling from library/traefik
+aad63a933944: Pull complete
+f365f1b91ebb: Pull complete
+dc367a6045f5: Pull complete
+ff697159d003: Pull complete
+Digest: sha256:615483752426932469aa2229ef3f0825b33b3ad7e1326dcd388205cb3a74352e
+Status: Downloaded newer image for traefik:2.2
+Creating traefik-golang_backend_1 ... done
+Creating traefik-golang_frontend_1 ... done
+```
+
+## Expected result
+
+Listing containers must show two containers running and the port mapping as below:
+```
+$ docker ps
+CONTAINER ID        IMAGE                    COMMAND                  CREATED             STATUS              PORTS  
+              NAMES
+e845f50da9e6        traefik:2.2              "/entrypoint.sh --pr…"   55 seconds ago      Up 54 seconds       0.0.0.0:80->80/tcp   traefik-golang_frontend_1
+e164ffd692e8        traefik-golang_backend   "/usr/local/bin/back…"   55 seconds ago      Up 54 seconds
+              traefik-golang_backend_1
+```
+
+After the application starts, navigate to `http://localhost:80` in your web browser or run:
+```
+$ curl localhost:80
+
+          ##         .
+    ## ## ##        ==
+ ## ## ## ## ##    ===
+/"""""""""""""""""\___/ ===
+{                       /  ===-
+\______ O           __/
+ \    \         __/
+  \____\_______/
+
+	
+Hello from Docker!
+```
+
+Stop and remove the containers
+```
+$ docker-compose down
+```

traefik-golang/backend/Dockerfile

@@ -0,0 +1,11 @@
+FROM golang:1.13 AS build
+
+WORKDIR /compose/hello-docker
+COPY main.go main.go
+RUN CGO_ENABLED=0 go build -o backend main.go
+
+FROM scratch
+COPY --from=build /compose/hello-docker/backend /usr/local/bin/backend
+CMD ["/usr/local/bin/backend"]
+
+

traefik-golang/backend/main.go

@@ -0,0 +1,30 @@
+package main
+
+import (
+	"fmt"
+	"log"
+	"net/http"
+)
+
+func handler(w http.ResponseWriter, r *http.Request) {
+	fmt.Println(r.URL.RawQuery)
+	fmt.Fprintf(w, `
+          ##         .
+    ## ## ##        ==
+ ## ## ## ## ##    ===
+/"""""""""""""""""\___/ ===
+{                       /  ===-
+\______ O           __/
+ \    \         __/
+  \____\_______/
+
+	
+Hello from Docker!
+
+`)
+}
+
+func main() {
+	http.HandleFunc("/", handler)
+	log.Fatal(http.ListenAndServe(":80", nil))
+}

traefik-golang/docker-compose.yml

@@ -0,0 +1,19 @@
+version: "3.7"
+services:
+  frontend:
+    image: traefik:2.2
+    command: --providers.docker --entrypoints.web.address=:80 --providers.docker.exposedbydefault=false
+    ports:
+      # The HTTP port
+      - "80:80"
+    volumes:
+      # So that Traefik can listen to the Docker events
+      - /var/run/docker.sock:/var/run/docker.sock
+    depends_on:
+      - backend
+  backend:
+    build: backend
+    labels:
+      - "traefik.enable=true"
+      - "traefik.http.routers.go.rule=Path(`/`)"
+      - "traefik.http.services.go.loadbalancer.server.port=80"