Add initial discovery service client

disco/client.go

@@ -0,0 +1,66 @@
+// Package disco controls interaction with the rqlite Discovery service
+package disco
+
+import (
+	"bytes"
+	"encoding/json"
+	"errors"
+	"io/ioutil"
+	"net/http"
+	"runtime"
+)
+
+type Nodes []string
+
+// Client provides a Discovery Service client.
+type Client struct {
+	url string
+}
+
+// New returns an uninitialized Discovery Service client.
+func New(url string) *Client {
+	return &Client{
+		url: url,
+	}
+}
+
+// URL returns the Discovery Service URL used by this client.
+func (c *Client) URL() string {
+	return c.url
+}
+
+// Register attempts to register with the Discovery Service, using the given
+// address.
+func (c *Client) Register(addr string) (Nodes, error) {
+	m := map[string]string{
+		"addr":   addr,
+		"GOOS":   runtime.GOOS,
+		"GOARCH": runtime.GOARCH,
+	}
+	b, err := json.Marshal(m)
+	if err != nil {
+		return nil, err
+	}
+
+	resp, err := http.Post(c.url, "application-type/json", bytes.NewReader(b))
+	if err != nil {
+		return nil, err
+	}
+	defer resp.Body.Close()
+
+	b, err = ioutil.ReadAll(resp.Body)
+	if err != nil {
+		return nil, err
+	}
+
+	if resp.StatusCode != http.StatusOK {
+		return nil, errors.New(resp.Status)
+	}
+
+	nodes := Nodes{}
+	if err := json.Unmarshal(b, &nodes); err != nil {
+		return nil, err
+	}
+
+	return nodes, nil
+}

disco/client_test.go

@@ -0,0 +1,176 @@
+package disco
+
+import (
+	"encoding/json"
+	"fmt"
+	"io/ioutil"
+	"net/http"
+	"net/http/httptest"
+	"runtime"
+	"testing"
+)
+
+func Test_NewClient(t *testing.T) {
+	c := New("https://discovery.rqlite.com")
+	if c == nil {
+		t.Fatal("failed to create new disco client")
+	}
+
+	if c.URL() != "https://discovery.rqlite.com" {
+		t.Fatal("configured address of disco service is incorrect")
+	}
+}
+
+func Test_ClientRegisterBadRequest(t *testing.T) {
+	ts := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		if r.Method != "POST" {
+			t.Fatalf("Client did not use POST")
+		}
+		w.WriteHeader(http.StatusBadRequest)
+	}))
+	defer ts.Close()
+
+	c := New(ts.URL)
+	_, err := c.Register("http://127.0.0.1")
+	if err == nil {
+		t.Fatalf("failed to receive error on 400 from server")
+	}
+}
+
+func Test_ClientRegisterNotFound(t *testing.T) {
+	ts := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		if r.Method != "POST" {
+			t.Fatalf("Client did not use POST")
+		}
+		w.WriteHeader(http.StatusNotFound)
+	}))
+	defer ts.Close()
+
+	c := New(ts.URL)
+	_, err := c.Register("http://127.0.0.1")
+	if err == nil {
+		t.Fatalf("failed to receive error on 404 from server")
+	}
+}
+
+func Test_ClientRegisterForbidden(t *testing.T) {
+	ts := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		if r.Method != "POST" {
+			t.Fatalf("Client did not use POST")
+		}
+		w.WriteHeader(http.StatusForbidden)
+	}))
+	defer ts.Close()
+
+	c := New(ts.URL)
+	_, err := c.Register("http://127.0.0.1")
+	if err == nil {
+		t.Fatalf("failed to receive error on 403 from server")
+	}
+}
+
+func Test_ClientRegisterRequestOK(t *testing.T) {
+	ts := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		if r.Method != "POST" {
+			t.Fatalf("Client did not use POST")
+		}
+
+		b, err := ioutil.ReadAll(r.Body)
+		if err != nil {
+			t.Fatalf("failed to read request from client: %s", err.Error())
+		}
+
+		m := map[string]string{}
+		if err := json.Unmarshal(b, &m); err != nil {
+			t.Fatalf("failed to unmarshal request from client: %s", err.Error())
+		}
+
+		if m["addr"] != "http://127.0.0.1" {
+			t.Fatalf("incorrect join address supplied by client: %s", m["addr"])
+		}
+		if m["GOOS"] != runtime.GOOS {
+			t.Fatalf("incorrect GOOS supplied by client: %s", m["GOOS"])
+		}
+		if m["GOARCH"] != runtime.GOARCH {
+			t.Fatalf("incorrect GOOS supplied by client: %s", m["GOARCH"])
+		}
+
+		fmt.Fprintln(w, `[]`)
+	}))
+	defer ts.Close()
+
+	c := New(ts.URL)
+	nodes, err := c.Register("http://127.0.0.1")
+	if err != nil {
+		t.Fatalf("failed to register: %s", err.Error())
+	}
+	if len(nodes) != 0 {
+		t.Fatalf("failed to receive empty list of nodes, got %v", nodes)
+	}
+}
+
+func Test_ClientRegisterLeaderOK(t *testing.T) {
+	ts := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		if r.Method != "POST" {
+			t.Fatalf("Client did not use POST")
+		}
+		fmt.Fprintln(w, `[]`)
+	}))
+	defer ts.Close()
+
+	c := New(ts.URL)
+	nodes, err := c.Register("http://127.0.0.1")
+	if err != nil {
+		t.Fatalf("failed to register: %s", err.Error())
+	}
+	if len(nodes) != 0 {
+		t.Fatalf("failed to receive empty list of nodes, got %v", nodes)
+	}
+}
+
+func Test_ClientRegisterFollowerOK(t *testing.T) {
+	ts := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		if r.Method != "POST" {
+			t.Fatalf("Client did not use POST")
+		}
+		fmt.Fprintln(w, `["http://1.1.1.1"]`)
+	}))
+	defer ts.Close()
+
+	c := New(ts.URL)
+	nodes, err := c.Register("http://2.2.2.2")
+	if err != nil {
+		t.Fatalf("failed to register: %s", err.Error())
+	}
+	if len(nodes) != 1 {
+		t.Fatalf("failed to receive non-empty list of nodes")
+	}
+	if nodes[0] != `http://1.1.1.1` {
+		t.Fatalf("got incorrect node, got %v", nodes[0])
+	}
+}
+
+func Test_ClientRegisterFollowerMultiOK(t *testing.T) {
+	ts := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		if r.Method != "POST" {
+			t.Fatalf("Client did not use POST")
+		}
+		fmt.Fprintln(w, `["http://1.1.1.1", "http://2.2.2.2"]`)
+	}))
+	defer ts.Close()
+
+	c := New(ts.URL)
+	nodes, err := c.Register("http://3.3.3.3")
+	if err != nil {
+		t.Fatalf("failed to register: %s", err.Error())
+	}
+	if len(nodes) != 2 {
+		t.Fatalf("failed to receive non-empty list of nodes")
+	}
+	if nodes[0] != `http://1.1.1.1` {
+		t.Fatalf("got incorrect first node, got %v", nodes[0])
+	}
+	if nodes[1] != `http://2.2.2.2` {
+		t.Fatalf("got incorrect second node, got %v", nodes[1])
+	}
+}