Discover a versioned container image tag

This change implements a discover_image_tag method to discover the
versioned tag for a container image.

The current approach is to expect a label to be set on the image which
contains the expected tag value. For example the RDO image building
pipeline sets a label rdo_version whose value also matches a tag.

This change will be used by the python-tripleoclient change which
actually implements the command
"openstack overcloud container image tag discover".

Change-Id: I27ea031287604d70032fb5392aecbce313d4b096
Partial-Bug: #1708967

tripleo_common/image/image_uploader.py

@@ -15,6 +15,7 @@
 
 
 import abc
+import json
 import logging
 import netifaces
 import six
@@ -38,6 +39,11 @@ class ImageUploadManager(BaseImageManager):
     def __init__(self, config_files, verbose=False, debug=False):
         super(ImageUploadManager, self).__init__(config_files)
 
+    def discover_image_tag(self, image, tag_from_label=None):
+        uploader = ImageUploader.get_uploader('docker')
+        return uploader.discover_image_tag(
+            image, tag_from_label=tag_from_label)
+
     def upload(self):
         """Start the upload process"""
 
@@ -89,6 +95,11 @@ class ImageUploader(object):
         """Upload a disk image"""
         pass
 
+    @abc.abstractmethod
+    def discover_image_tag(self, image, tag_from_label=None):
+        """Discover a versioned tag for an image"""
+        pass
+
 
 class DockerImageUploader(ImageUploader):
     """Upload images using docker push"""
@@ -108,9 +119,7 @@ class DockerImageUploader(ImageUploader):
         else:
             repo = image
 
-        response = [line for line in dockerc.pull(repo,
-                    tag=tag, stream=True)]
-        self.logger.debug(response)
+        self._pull(dockerc, repo, tag=tag)
 
         full_image = repo + ':' + tag
         new_repo = push_destination + '/' + repo.partition('/')[2]
@@ -123,3 +132,44 @@ class DockerImageUploader(ImageUploader):
         self.logger.debug(response)
 
         self.logger.info('Completed upload for docker image %s' % image_name)
+
+    def _pull(self, dockerc, image, tag=None):
+        self.logger.debug('Pulling %s' % image)
+        for line in dockerc.pull(image, tag=tag, stream=True):
+            status = json.loads(line)
+            if 'error' in status:
+                raise ImageUploaderException('Could not pull image: %s' %
+                                             status['error'])
+            self.logger.debug(status.get('status'))
+
+    def discover_image_tag(self, image, tag_from_label=None):
+        dockerc = Client(base_url='unix://var/run/docker.sock', version='auto')
+
+        image_name, colon, tag = image.partition(':')
+        if not tag:
+            tag = 'latest'
+        image = '%s:%s' % (image_name, tag)
+
+        self._pull(dockerc, image)
+        i = dockerc.inspect_image(image)
+        labels = i['Config']['Labels']
+
+        label_keys = ', '.join(labels.keys())
+
+        if not tag_from_label:
+            raise ImageUploaderException(
+                'No label specified. Available labels: %s' % label_keys
+            )
+
+        tag_label = labels.get(tag_from_label)
+        if tag_label is None:
+            raise ImageUploaderException(
+                'Image %s has no label %s. Available labels: %s' %
+                (image, tag_from_label, label_keys)
+            )
+
+        # confirm the tag exists by pulling it, which should be fast
+        # because that image has just been pulled
+        versioned_image = '%s:%s' % (image_name, tag_label)
+        self._pull(dockerc, versioned_image)
+        return tag_label

tripleo_common/tests/image/test_image_uploader.py

@@ -173,3 +173,87 @@ class TestDockerImageUploader(base.TestCase):
         self.dockermock.return_value.push(
             push_destination + '/' + image,
             tag=expected_tag, stream=True)
+
+    def test_discover_image_tag(self):
+        image = 'docker.io/tripleoupstream/heat-docker-agents-centos:latest'
+        vimage = 'docker.io/tripleoupstream/heat-docker-agents-centos:1.2.3'
+
+        dockerc = self.dockermock.return_value
+        dockerc.pull.return_value = ['{"status": "done"}']
+        dockerc.inspect_image.return_value = {
+            'Config': {'Labels': {'image-version': '1.2.3'}}
+        }
+        result = self.uploader.discover_image_tag(image, 'image-version')
+        self.assertEqual('1.2.3', result)
+
+        self.dockermock.assert_called_once_with(
+            base_url='unix://var/run/docker.sock', version='auto')
+
+        dockerc.pull.assert_has_calls([
+            mock.call(image, tag=None, stream=True),
+            mock.call(vimage, tag=None, stream=True),
+        ])
+
+    def test_discover_image_tag_no_latest(self):
+        image = 'docker.io/tripleoupstream/heat-docker-agents-centos'
+        limage = image + ':latest'
+        vimage = image + ':1.2.3'
+
+        dockerc = self.dockermock.return_value
+        dockerc.pull.return_value = ['{"status": "done"}']
+        dockerc.inspect_image.return_value = {
+            'Config': {'Labels': {'image-version': '1.2.3'}}
+        }
+        result = self.uploader.discover_image_tag(image, 'image-version')
+        self.assertEqual('1.2.3', result)
+
+        dockerc.pull.assert_has_calls([
+            mock.call(limage, tag=None, stream=True),
+            mock.call(vimage, tag=None, stream=True),
+        ])
+
+    def test_discover_image_tag_no_tag_from_image(self):
+        image = 'docker.io/tripleoupstream/heat-docker-agents-centos:latest'
+
+        dockerc = self.dockermock.return_value
+        dockerc.pull.return_value = ['{"status": "done"}']
+        dockerc.inspect_image.return_value = {
+            'Config': {'Labels': {'image-version': '1.2.3'}}
+        }
+        self.assertRaises(ImageUploaderException,
+                          self.uploader.discover_image_tag, image)
+
+    def test_discover_image_tag_missing_label(self):
+        image = 'docker.io/tripleoupstream/heat-docker-agents-centos:latest'
+
+        dockerc = self.dockermock.return_value
+        dockerc.pull.return_value = ['{"status": "done"}']
+        dockerc.inspect_image.return_value = {
+            'Config': {'Labels': {'image-version': '1.2.3'}}
+        }
+        self.assertRaises(ImageUploaderException,
+                          self.uploader.discover_image_tag, image, 'foo')
+
+    def test_discover_image_tag_missing_tag(self):
+        image = 'docker.io/tripleoupstream/heat-docker-agents-centos:latest'
+        vimage = 'docker.io/tripleoupstream/heat-docker-agents-centos:1.2.3'
+
+        dockerc = self.dockermock.return_value
+        dockerc.pull.side_effect = [
+            ['{"status": "done"}'],  # First pull, :latest
+            ['{"error": "ouch"}'],  # Second pull, :1.2.3
+        ]
+        dockerc.inspect_image.return_value = {
+            'Config': {'Labels': {'image-version': '1.2.3'}}
+        }
+        self.assertRaises(ImageUploaderException,
+                          self.uploader.discover_image_tag, image,
+                          'image-version')
+
+        self.dockermock.assert_called_once_with(
+            base_url='unix://var/run/docker.sock', version='auto')
+
+        dockerc.pull.assert_has_calls([
+            mock.call(image, tag=None, stream=True),
+            mock.call(vimage, tag=None, stream=True),
+        ])