Add gRPC user guide

.github/ISSUE_TEMPLATE.md

@@ -4,7 +4,6 @@ DO NOT FILE ISSUES FOR GENERAL SUPPORT QUESTIONS.
 The issue tracker is for reporting bugs and feature requests only.
 For end-user related support questions, please refer to one of the following:
 
-- Stack Overflow (using the "traefik" tag): https://stackoverflow.com/questions/tagged/traefik
 - the Traefik community forum: https://community.containo.us/
 
 -->

.github/ISSUE_TEMPLATE/Bug_report.md

@@ -10,7 +10,6 @@ DO NOT FILE ISSUES FOR GENERAL SUPPORT QUESTIONS.
 The issue tracker is for reporting bugs and feature requests only.
 For end-user related support questions, please refer to one of the following:
 
-- Stack Overflow (using the "traefik" tag): https://stackoverflow.com/questions/tagged/traefik
 - the Traefik community forum: https://community.containo.us/
 
 -->

.github/ISSUE_TEMPLATE/Feature_request.md

@@ -10,7 +10,6 @@ DO NOT FILE ISSUES FOR GENERAL SUPPORT QUESTIONS.
 The issue tracker is for reporting bugs and feature requests only.
 For end-user related support questions, please refer to one of the following:
 
-- Stack Overflow (using the "traefik" tag): https://stackoverflow.com/questions/tagged/traefik
 - the Traefik community forum: https://community.containo.us/
 
 -->

README.md

@@ -104,7 +104,6 @@ A collection of contributions around Traefik can be found at [https://awesome.tr
 
 To get community support, you can:
 - join the Traefik community forum: [![Join the chat at https://community.containo.us/](https://img.shields.io/badge/style-register-green.svg?style=social&label=Discourse)](https://community.containo.us/)
-- use [Stack Overflow](https://stackoverflow.com/questions/tagged/traefik) (using the `traefik` tag)
 
 If you need commercial support, please contact [Containo.us](https://containo.us) by mail: <mailto:support@containo.us>.
 

docs/.markdownlint.json

@@ -3,6 +3,7 @@
     "MD007": { "indent": 4 },
     "MD009": false,
     "MD013": false,
+    "MD024": false,
     "MD026": false,
     "MD033": false,
     "MD034": false,

docs/content/contributing/submitting-issues.md

@@ -15,7 +15,6 @@ To save us some time and get quicker feedback, be sure to follow the guide lines
     For end-user related support questions, try using first:
 
     - the Traefik community forum: [![Join the chat at https://community.containo.us/](https://img.shields.io/badge/style-register-green.svg?style=social&label=Discourse)](https://community.containo.us/)
-    - [Stack Overflow](https://stackoverflow.com/questions/tagged/traefik) (using the `traefik` tag)
 
 ## Issue Title
 

docs/content/user-guides/grpc.md

@@ -0,0 +1,252 @@
+# gRPC Examples
+
+## With HTTP (h2c)
+
+This section explains how to use Traefik as reverse proxy for gRPC application.
+
+### Traefik Configuration
+
+```toml tab="TOML"
+## static configuration ##
+
+[entryPoints]
+  [entryPoints.http]
+    address = ":80"
+
+[api]
+    
+[providers.file]
+
+## dynamic configuration ##
+
+[http]
+
+  [http.routers]
+    [http.routers.routerTest]
+      service = "srv-grpc"
+      rule = "Host(`frontend.local`)"
+    
+  [http.services]
+    [http.services.srv-grpc]
+      [http.services.srv-grpc.loadBalancer]
+        [[http.services.srv-grpc.loadBalancer.servers]]
+          url = "h2c://backend.local:8080"
+```
+
+```yaml tab="YAML"
+## static configuration ##
+
+entryPoints:
+  http:
+    address: :80
+
+providers:
+  file: {}
+
+api: {}
+
+## dynamic configuration ##
+
+http:
+  routers:
+    routerTest:
+      service: srv-grpc
+      rule: Host(`frontend.local`)
+
+  services:
+    srv-grpc:
+      loadBalancer:
+        servers:
+        - url: h2c://backend.local:8080
+```
+
+!!! warning
+    For providers with labels, you will have to specify the `traefik.http.services.<my-service-name>.loadbalancer.server.scheme=h2c`
+
+### Conclusion
+
+We don't need specific configuration to use gRPC in Traefik, we just need to use `h2c` protocol, or use HTTPS communications to have HTTP2 with the backend.
+
+## With HTTPS
+
+This section explains how to use Traefik as reverse proxy for gRPC application with self-signed certificates.
+
+![gRPC architecture](../assets/img/user-guides/grpc.svg)
+
+### gRPC Server Certificate
+
+In order to secure the gRPC server, we generate a self-signed certificate for service url:
+
+```bash
+openssl req -x509 -nodes -days 365 -newkey rsa:2048 -keyout ./backend.key -out ./backend.cert
+```
+
+That will prompt for information, the important answer is:
+
+```txt
+Common Name (e.g. server FQDN or YOUR name) []: backend.local
+```
+
+### gRPC Client Certificate
+
+Generate your self-signed certificate for router url:
+
+```bash
+openssl req -x509 -nodes -days 365 -newkey rsa:2048 -keyout ./frontend.key -out ./frontend.cert
+```
+
+with
+
+```txt
+Common Name (e.g. server FQDN or YOUR name) []: frontend.local
+```
+
+### Traefik Configuration
+
+At last, we configure our Traefik instance to use both self-signed certificates.
+
+```toml tab="TOML"
+## static configuration ##
+
+[entryPoints]
+  [entryPoints.https]
+    address = ":4443"
+
+
+[serversTransport]
+  # For secure connection on backend.local
+  rootCAs = [ "./backend.cert" ]
+
+[api]
+
+[provider.file]
+
+## dynamic configuration ##
+
+[http]
+
+  [http.routers]
+    [http.routers.routerTest]
+      service = "srv-grpc"
+      rule = "Host(`frontend.local`)"
+    
+  [http.services]
+    [http.services.srv-grpc]
+      [http.services.srv-grpc.loadBalancer]
+        [[http.services.srv-grpc.loadBalancer.servers]]
+          # Access on backend with HTTPS
+          url = "https://backend.local:8080"
+
+[tls]
+
+  # For secure connection on frontend.local
+  [[tls.certificates]]
+    certFile = "./frontend.cert"
+    keyFile = "./frontend.key"
+```
+
+```yaml tab="YAML"
+## static configuration ##
+
+entryPoints:
+  https:
+    address: :4443
+
+serversTransport:
+  # For secure connection on backend.local
+  rootCAs:
+  - ./backend.cert
+
+providers:
+  file: {}
+
+api: {}
+
+## dynamic configuration ##
+
+http:
+  routers:
+    routerTest:
+      service: srv-grpc
+      rule: Host(`frontend.local`)
+  services:
+    srv-grpc:
+      loadBalancer:
+        servers:
+        # Access on backend with HTTPS
+        - url: https://backend.local:8080
+tls:
+  # For secure connection on frontend.local
+  certificates:
+  - certfile: ./frontend.cert
+    keyfile: ./frontend.key
+```
+
+!!! warning
+    With some services, the server URLs use the IP, so you may need to configure `insecureSkipVerify` instead of the `rootCAs` to activate HTTPS without hostname verification.
+
+### A gRPC example in go (modify for https)
+
+We use the gRPC greeter example in [grpc-go](https://github.com/grpc/grpc-go/tree/master/examples/helloworld)
+
+!!! warning
+    In order to use this gRPC example, we need to modify it to use HTTPS
+
+So we modify the "gRPC server example" to use our own self-signed certificate:
+
+```go
+// ...
+
+// Read cert and key file
+backendCert, _ := ioutil.ReadFile("./backend.cert")
+backendKey, _ := ioutil.ReadFile("./backend.key")
+
+// Generate Certificate struct
+cert, err := tls.X509KeyPair(backendCert, backendKey)
+if err != nil {
+  log.Fatalf("failed to parse certificate: %v", err)
+}
+
+// Create credentials
+creds := credentials.NewServerTLSFromCert(&cert)
+
+// Use Credentials in gRPC server options
+serverOption := grpc.Creds(creds)
+var s *grpc.Server = grpc.NewServer(serverOption)
+defer s.Stop()
+
+pb.RegisterGreeterServer(s, &server{})
+err := s.Serve(lis)
+
+// ...
+```
+
+Next we will modify gRPC Client to use our Traefik self-signed certificate:
+
+```go
+// ...
+
+// Read cert file
+frontendCert, _ := ioutil.ReadFile("./frontend.cert")
+
+// Create CertPool
+roots := x509.NewCertPool()
+roots.AppendCertsFromPEM(frontendCert)
+
+// Create credentials
+credsClient := credentials.NewClientTLSFromCert(roots, "")
+
+// Dial with specific Transport (with credentials)
+conn, err := grpc.Dial("frontend.local:4443", grpc.WithTransportCredentials(credsClient))
+if err != nil {
+    log.Fatalf("did not connect: %v", err)
+}
+
+defer conn.Close()
+client := pb.NewGreeterClient(conn)
+
+name := "World"
+r, err := client.SayHello(context.Background(), &pb.HelloRequest{Name: name})
+
+// ...
+```

docs/mkdocs.yml

@@ -128,6 +128,7 @@ nav:
           - 'Haystack': 'observability/tracing/haystack.md'
   - 'User Guides':
       - 'Kubernetes and Let''s Encrypt': 'user-guides/crd-acme/index.md'
+      - 'gRPC Examples': 'user-guides/grpc.md'
       - 'Marathon': 'user-guides/marathon.md'
   - 'Contributing':
       - 'Thank You!': 'contributing/thank-you.md'