client: Expose DaemonHost to client users

This commit exposes `Client.host` as `Client.DaemonHost()`
This allows users of the client, a CLI for example, to query the Host
that the client is attempting to contact and vary their behaviour
accordingly. For example, to allow client-side configuration of
HTTP proxy settings for a number of different docker hosts.

Signed-off-by: Dave Tucker <dt@docker.com>

client/client.go

@@ -247,6 +247,12 @@ func (cli *Client) UpdateClientVersion(v string) {
 
 }
 
+// DaemonHost returns the host associated with this instance of the Client.
+// This operation doesn't acquire a mutex.
+func (cli *Client) DaemonHost() string {
+	return cli.host
+}
+
 // ParseHost verifies that the given host strings is valid.
 func ParseHost(host string) (string, string, string, error) {
 	protoAddrParts := strings.SplitN(host, "://", 2)

client/interface.go

@@ -31,6 +31,7 @@ type CommonAPIClient interface {
 	SystemAPIClient
 	VolumeAPIClient
 	ClientVersion() string
+	DaemonHost() string
 	ServerVersion(ctx context.Context) (types.Version, error)
 	UpdateClientVersion(v string)
 }