Add context.RequestID to event stream

This PR adds a "request ID" to each event generated, the 'docker events'
stream now looks like this:

```
2015-09-10T15:02:50.000000000-07:00 [reqid: c01e3534ddca] de7c5d4ca927253cf4e978ee9c4545161e406e9b5a14617efb52c658b249174a: (from ubuntu) create
```
Note the `[reqID: c01e3534ddca]` part, that's new.

Each HTTP request will generate its own unique ID. So, if you do a
`docker build` you'll see a series of events all with the same reqID.
This allow for log processing tools to determine which events are all related
to the same http request.

I didn't propigate the context to all possible funcs in the daemon,
I decided to just do the ones that needed it in order to get the reqID
into the events. I'd like to have people review this direction first, and
if we're ok with it then I'll make sure we're consistent about when
we pass around the context - IOW, make sure that all funcs at the same level
have a context passed in even if they don't call the log funcs - this will
ensure we're consistent w/o passing it around for all calls unnecessarily.

ping @icecrime @calavera @crosbymichael

Signed-off-by: Doug Davis <dug@us.ibm.com>

1 files changed, 6 insertions, 5 deletions

diff --git a/daemon/container_windows.go b/daemon/container_windows.go
index 38e0a120c5..e56b7e2d1a 100644
--- a/daemon/container_windows.go
+++ b/daemon/container_windows.go
@@ -5,6 +5,7 @@ package daemon
 import (
 	"strings"
 
+	"github.com/docker/docker/context"
 	"github.com/docker/docker/daemon/execdriver"
 	derr "github.com/docker/docker/errors"
 )
@@ -25,7 +26,7 @@ func killProcessDirectly(container *Container) error {
 	return nil
 }
 
-func (container *Container) setupLinkedContainers() ([]string, error) {
+func (container *Container) setupLinkedContainers(ctx context.Context) ([]string, error) {
 	return nil, nil
 }
 
@@ -34,7 +35,7 @@ func (container *Container) createDaemonEnvironment(linkedEnv []string) []string
 	return container.Config.Env
 }
 
-func (container *Container) initializeNetworking() error {
+func (container *Container) initializeNetworking(ctx context.Context) error {
 	return nil
 }
 
@@ -42,7 +43,7 @@ func (container *Container) setupWorkingDirectory() error {
 	return nil
 }
 
-func populateCommand(c *Container, env []string) error {
+func populateCommand(ctx context.Context, c *Container, env []string) error {
 	en := &execdriver.Network{
 		Interface: nil,
 	}
@@ -135,7 +136,7 @@ func populateCommand(c *Container, env []string) error {
 }
 
 // GetSize returns real size & virtual size
-func (container *Container) getSize() (int64, int64) {
+func (container *Container) getSize(ctx context.Context) (int64, int64) {
 	// TODO Windows
 	return 0, 0
 }
@@ -150,7 +151,7 @@ func (container *Container) allocateNetwork() error {
 	return nil
 }
 
-func (container *Container) updateNetwork() error {
+func (container *Container) updateNetwork(ctx context.Context) error {
 	return nil
 }