Add HTTP Provider

* feat: add HTTP provider implementation

* refactor: add SetDefaults and struct tag for the new file parser

* feat: add TLS configuration property

* refactor: rework HTTP provider implementation

* feat: provide config only once if fetched config is unchanged

* style: lint

* ui: add HTTP provider icon

* tests: simplify and fix integration test

* docs: add reference config for file

* docs: move http reference config for file

Co-authored-by: Daniel Tomcej <daniel.tomcej@gmail.com>

integration/http_test.go

@@ -0,0 +1,87 @@
+package integration
+
+import (
+	"encoding/json"
+	"net"
+	"net/http"
+	"net/http/httptest"
+	"time"
+
+	"github.com/containous/traefik/v2/integration/try"
+	"github.com/containous/traefik/v2/pkg/config/dynamic"
+	"github.com/go-check/check"
+	checker "github.com/vdemeester/shakers"
+)
+
+type HTTPSuite struct{ BaseSuite }
+
+func (s *HTTPSuite) TestSimpleConfiguration(c *check.C) {
+	cmd, display := s.traefikCmd(withConfigFile("fixtures/http/simple.toml"))
+	defer display(c)
+
+	err := cmd.Start()
+	c.Assert(err, checker.IsNil)
+
+	defer cmd.Process.Kill()
+
+	// Expect a 404 as we configured nothing.
+	err = try.GetRequest("http://127.0.0.1:8000/", time.Second, try.StatusCodeIs(http.StatusNotFound))
+	c.Assert(err, checker.IsNil)
+
+	// Provide a configuration, fetched by Traefik provider.
+	configuration := &dynamic.Configuration{
+		HTTP: &dynamic.HTTPConfiguration{
+			Routers: map[string]*dynamic.Router{
+				"routerHTTP": {
+					EntryPoints: []string{"web"},
+					Middlewares: []string{},
+					Service:     "serviceHTTP",
+					Rule:        "PathPrefix(`/`)",
+				},
+			},
+			Services: map[string]*dynamic.Service{
+				"serviceHTTP": {
+					LoadBalancer: &dynamic.ServersLoadBalancer{
+						PassHostHeader: boolRef(true),
+						Servers: []dynamic.Server{
+							{
+								URL: "http://bacon:80",
+							},
+						},
+					},
+				},
+			},
+		},
+	}
+
+	configData, err := json.Marshal(configuration)
+	c.Assert(err, checker.IsNil)
+
+	server := startTestServerWithResponse(configData)
+	defer server.Close()
+
+	// Expect configuration to be applied.
+	err = try.GetRequest("http://127.0.0.1:9090/api/rawdata", 3*time.Second, try.BodyContains("routerHTTP@http", "serviceHTTP@http", "http://bacon:80"))
+	c.Assert(err, checker.IsNil)
+}
+
+func startTestServerWithResponse(response []byte) (ts *httptest.Server) {
+	handler := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		_, _ = w.Write(response)
+	})
+	listener, err := net.Listen("tcp", "127.0.0.1:9000")
+	if err != nil {
+		panic(err)
+	}
+
+	ts = &httptest.Server{
+		Listener: listener,
+		Config:   &http.Server{Handler: handler},
+	}
+	ts.Start()
+	return ts
+}
+
+func boolRef(b bool) *bool {
+	return &b
+}