From 32a12578f3b7d33951fa684abfc485a8b308fe5b Mon Sep 17 00:00:00 2001
From: Paul Bellamy <paul.a.bellamy@gmail.com>
Date: Wed, 2 Sep 2015 13:39:57 +0100
Subject: [PATCH] Don't use go-dockerclient to en/decode inspects in the proxy

---
 proxy/common.go                        |  4 +--
 proxy/inspect_container_interceptor.go | 26 ++++++++++-----
 proxy/inspect_exec_interceptor.go      | 12 ++++---
 proxy/json.go                          | 46 ++++++++++++++++++++++++++
 4 files changed, 73 insertions(+), 15 deletions(-)
 create mode 100644 proxy/json.go

diff --git a/proxy/common.go b/proxy/common.go
index 323b9611..7579cf99 100644
--- a/proxy/common.go
+++ b/proxy/common.go
@@ -105,8 +105,8 @@ func inspectContainerInPath(client *docker.Client, path string) (*docker.Contain
 	return container, err
 }
 
-func weaveContainerIPs(container *docker.Container) (mac string, ips []net.IP, nets []*net.IPNet, err error) {
-	stdout, stderr, err := callWeave("ps", container.ID)
+func weaveContainerIPs(containerID string) (mac string, ips []net.IP, nets []*net.IPNet, err error) {
+	stdout, stderr, err := callWeave("ps", containerID)
 	if err != nil || len(stderr) > 0 {
 		err = errors.New(string(stderr))
 		return
diff --git a/proxy/inspect_container_interceptor.go b/proxy/inspect_container_interceptor.go
index 2010660b..59f9a062 100644
--- a/proxy/inspect_container_interceptor.go
+++ b/proxy/inspect_container_interceptor.go
@@ -3,7 +3,6 @@ package proxy
 import (
 	"net/http"
 
-	"github.com/fsouza/go-dockerclient"
 	. "github.com/weaveworks/weave/common"
 )
 
@@ -18,26 +17,35 @@ func (i *inspectContainerInterceptor) InterceptResponse(r *http.Response) error
 		return nil
 	}
 
-	container := &docker.Container{}
-	if err := unmarshalResponseBody(r, container); err != nil {
+	container := map[string]interface{}{}
+	if err := unmarshalResponseBody(r, &container); err != nil {
 		return err
 	}
 
 	if err := updateContainerNetworkSettings(container); err != nil {
-		Log.Warningf("Inspecting container %s failed: %s", container.ID, err)
+		Log.Warningf("Inspecting container %s failed: %s", container["Id"], err)
 	}
 
 	return marshalResponseBody(r, container)
 }
 
-func updateContainerNetworkSettings(container *docker.Container) error {
-	mac, ips, nets, err := weaveContainerIPs(container)
+func updateContainerNetworkSettings(container map[string]interface{}) error {
+	containerID, err := lookupString(container, "Id")
+	if err != nil {
+		return err
+	}
+
+	mac, ips, nets, err := weaveContainerIPs(containerID)
 	if err != nil || len(ips) == 0 {
 		return err
 	}
 
-	container.NetworkSettings.MacAddress = mac
-	container.NetworkSettings.IPAddress = ips[0].String()
-	container.NetworkSettings.IPPrefixLen, _ = nets[0].Mask.Size()
+	networkSettings, err := lookupObject(container, "NetworkSettings")
+	if err != nil {
+		return err
+	}
+	networkSettings["MacAddress"] = mac
+	networkSettings["IPAddress"] = ips[0].String()
+	networkSettings["IPPrefixLen"], _ = nets[0].Mask.Size()
 	return nil
 }
diff --git a/proxy/inspect_exec_interceptor.go b/proxy/inspect_exec_interceptor.go
index d787fcdf..89707146 100644
--- a/proxy/inspect_exec_interceptor.go
+++ b/proxy/inspect_exec_interceptor.go
@@ -3,7 +3,6 @@ package proxy
 import (
 	"net/http"
 
-	"github.com/fsouza/go-dockerclient"
 	. "github.com/weaveworks/weave/common"
 )
 
@@ -18,13 +17,18 @@ func (i *inspectExecInterceptor) InterceptResponse(r *http.Response) error {
 		return nil
 	}
 
-	exec := &docker.ExecInspect{}
+	exec := map[string]interface{}{}
 	if err := unmarshalResponseBody(r, &exec); err != nil {
 		return err
 	}
 
-	if err := updateContainerNetworkSettings(&exec.Container); err != nil {
-		Log.Warningf("Inspecting exec %s failed: %s", exec.ID, err)
+	container, err := lookupObject(exec, "Container")
+	if err != nil {
+		return err
+	}
+
+	if err := updateContainerNetworkSettings(container); err != nil {
+		Log.Warningf("Inspecting exec %s failed: %s", exec["Id"], err)
 	}
 
 	return marshalResponseBody(r, exec)
diff --git a/proxy/json.go b/proxy/json.go
new file mode 100644
index 00000000..d3728e18
--- /dev/null
+++ b/proxy/json.go
@@ -0,0 +1,46 @@
+package proxy
+
+import (
+	"fmt"
+)
+
+type UnmarshalWrongTypeError struct {
+	Field, Expected string
+	Got             interface{}
+}
+
+func (e *UnmarshalWrongTypeError) Error() string {
+	return fmt.Sprintf("Wrong type for %s field, expected %s, but got %T", e.Field, e.Expected, e.Got)
+}
+
+// For parsing json objects. Look up (or create) a child object in the given map.
+func lookupObject(m map[string]interface{}, key string) (map[string]interface{}, error) {
+	iface, ok := m[key]
+	if !ok || iface == nil {
+		result := map[string]interface{}{}
+		m[key] = result
+		return result, nil
+	}
+
+	result, ok := iface.(map[string]interface{})
+	if !ok {
+		return nil, &UnmarshalWrongTypeError{key, "object", iface}
+	}
+
+	return result, nil
+}
+
+// For parsing json objects. Look up (or create) a string in the given map.
+func lookupString(m map[string]interface{}, key string) (string, error) {
+	iface, ok := m[key]
+	if !ok || iface == nil {
+		return "", nil
+	}
+
+	result, ok := iface.(string)
+	if !ok {
+		return "", &UnmarshalWrongTypeError{key, "string", iface}
+	}
+
+	return result, nil
+}