Basic forward backend

backends/backends.go

@@ -16,5 +16,6 @@ func New() *engine.Engine {
 	// Register all backends here
 	Debug().Install(back)
 	Simulator().Install(back)
+	Forward().Install(back)
 	return back
 }

backends/forward.go

@@ -0,0 +1,87 @@
+package backends
+
+import (
+	"fmt"
+	"github.com/dotcloud/docker/engine"
+	"io/ioutil"
+	"net/http"
+	"net/url"
+	"strings"
+)
+
+func Forward() engine.Installer {
+	return &forwarder{}
+}
+
+type forwarder struct {
+}
+
+func (f *forwarder) Install(eng *engine.Engine) error {
+	eng.Register("forward", func(job *engine.Job) engine.Status {
+		if len(job.Args) != 1 {
+			return job.Errorf("usage: %s <proto>://<addr>", job.Name)
+		}
+		client, err := newClient(job.Args[0], "v0.10")
+		if err != nil {
+			return job.Errorf("%v", err)
+		}
+		job.Eng.Register("containers", func(job *engine.Job) engine.Status {
+			resp, err := client.call("GET", "/containers/json?all=1", "")
+			if err != nil {
+				return job.Errorf("%s: get: %v", client.URL.String(), err)
+			}
+			// FIXME: check for response error
+			c := engine.NewTable("Created", 0)
+			body, err := ioutil.ReadAll(resp.Body)
+			if err != nil {
+				return job.Errorf("%s: read body: %v", client.URL.String(), err)
+			}
+			fmt.Printf("---> '%s'\n", body)
+			if _, err := c.ReadListFrom(body); err != nil {
+				return job.Errorf("%s: readlist: %v", client.URL.String(), err)
+			}
+			c.WriteListTo(job.Stdout)
+			return engine.StatusOK
+		})
+		return engine.StatusOK
+	})
+	return nil
+}
+
+type client struct {
+	URL     *url.URL
+	proto   string
+	addr    string
+	version string
+}
+
+func newClient(peer, version string) (*client, error) {
+	u, err := url.Parse(peer)
+	if err != nil {
+		return nil, err
+	}
+	c := &client{
+		URL:     u,
+		version: version,
+	}
+	c.URL.Scheme = "http"
+	return c, nil
+}
+
+func (c *client) call(method, path, body string) (*http.Response, error) {
+	u, err := url.Parse(path)
+	if err != nil {
+		return nil, err
+	}
+	u.Host = c.URL.Host
+	u.Scheme = c.URL.Scheme
+	req, err := http.NewRequest(method, u.String(), strings.NewReader(body))
+	if err != nil {
+		return nil, err
+	}
+	resp, err := http.DefaultClient.Do(req)
+	if err != nil {
+		return nil, err
+	}
+	return resp, nil
+}