[PATCH v1 4/7] tests/docker: add "fetch" sub-command

["Alex Bennée" <alex.bennee@linaro.org>]

This simply wraps up fetching a build from the registry and tagging it
as the local build.

Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
---
 tests/docker/docker.py | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/tests/docker/docker.py b/tests/docker/docker.py
index 86d31a5fe6..f6f461bbc9 100755
--- a/tests/docker/docker.py
+++ b/tests/docker/docker.py
@@ -515,6 +515,23 @@ def run(self, args, argv):
 
         return 0
 
+class FetchCommand(SubCommand):
+    """ Fetch a docker image from the registry. Args: <tag> <registry>"""
+    name = "fetch"
+
+    def args(self, parser):
+        parser.add_argument("tag",
+                            help="Local tag for image")
+        parser.add_argument("registry",
+                            help="Docker registry")
+
+    def run(self, args, argv):
+        dkr = Docker()
+        dkr.command(cmd="pull", quiet=args.quiet,
+                    argv=["%s/%s" % (args.registry, args.tag)])
+        dkr.command(cmd="tag", quiet=args.quiet,
+                    argv=["%s/%s" % (args.registry, args.tag), args.tag])
+
 
 class UpdateCommand(SubCommand):
     """ Update a docker image. Args: <tag> <actions>"""
-- 
2.20.1