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Create extpoint for graphdrivers

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Allows people to create out-of-process graphdrivers that can be used
with Docker.

Extensions must be started before Docker otherwise Docker will fail to
start.

Signed-off-by: Brian Goff <cpuguy83@gmail.com>
This commit is contained in:
Brian Goff 2015-06-05 15:09:53 -05:00
parent 7ac0286ce7
commit 18649f7bf0
2 changed files with 35 additions and 14 deletions
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47
plugins/client.go
View file

@ -4,6 +4,7 @@ import (
"bytes"
"encoding/json"
"fmt"
"io"
"io/ioutil"
"net/http"
"strings"
@ -52,19 +53,41 @@ type Client struct {
// Call calls the specified method with the specified arguments for the plugin.
// It will retry for 30 seconds if a failure occurs when calling.
func (c *Client) Call(serviceMethod string, args interface{}, ret interface{}) error {
return c.callWithRetry(serviceMethod, args, ret, true)
}
func (c *Client) callWithRetry(serviceMethod string, args interface{}, ret interface{}, retry bool) error {
var buf bytes.Buffer
if err := json.NewEncoder(&buf).Encode(args); err != nil {
return err
}
req, err := http.NewRequest("POST", "/"+serviceMethod, &buf)
body, err := c.callWithRetry(serviceMethod, &buf, true)
if err != nil {
return err
}
defer body.Close()
return json.NewDecoder(body).Decode(&ret)
}
// Stream calls the specified method with the specified arguments for the plugin and returns the response body
func (c *Client) Stream(serviceMethod string, args interface{}) (io.ReadCloser, error) {
var buf bytes.Buffer
if err := json.NewEncoder(&buf).Encode(args); err != nil {
return nil, err
}
return c.callWithRetry(serviceMethod, &buf, true)
}
// SendFile calls the specified method, and passes through the IO stream
func (c *Client) SendFile(serviceMethod string, data io.Reader, ret interface{}) error {
body, err := c.callWithRetry(serviceMethod, data, true)
if err != nil {
return err
}
return json.NewDecoder(body).Decode(&ret)
}
func (c *Client) callWithRetry(serviceMethod string, data io.Reader, retry bool) (io.ReadCloser, error) {
req, err := http.NewRequest("POST", "/"+serviceMethod, data)
if err != nil {
return nil, err
}
req.Header.Add("Accept", versionMimetype)
req.URL.Scheme = "http"
req.URL.Host = c.addr
@ -76,12 +99,12 @@ func (c *Client) callWithRetry(serviceMethod string, args interface{}, ret inter
resp, err := c.http.Do(req)
if err != nil {
if !retry {
return err
return nil, err
}
timeOff := backoff(retries)
if abort(start, timeOff) {
return err
return nil, err
}
retries++
logrus.Warnf("Unable to connect to plugin: %s, retrying in %v", c.addr, timeOff)
@ -89,16 +112,14 @@ func (c *Client) callWithRetry(serviceMethod string, args interface{}, ret inter
continue
}
defer resp.Body.Close()
if resp.StatusCode != http.StatusOK {
remoteErr, err := ioutil.ReadAll(resp.Body)
if err != nil {
return &remoteError{err.Error(), serviceMethod}
return nil, &remoteError{err.Error(), serviceMethod}
}
return &remoteError{string(remoteErr), serviceMethod}
return nil, &remoteError{string(remoteErr), serviceMethod}
}
return json.NewDecoder(resp.Body).Decode(&ret)
return resp.Body, nil
}
}

2
plugins/client_test.go
View file

@ -30,7 +30,7 @@ func teardownRemotePluginServer() {
func TestFailedConnection(t *testing.T) {
c, _ := NewClient("tcp://127.0.0.1:1", tlsconfig.Options{InsecureSkipVerify: true})
err := c.callWithRetry("Service.Method", nil, nil, false)
_, err := c.callWithRetry("Service.Method", nil, false)
if err == nil {
t.Fatal("Unexpected successful connection")
}