add image_prefix validation

test image_prefix trait validation
add image name parser
simplify get_image_manifest method
extend get_image_manifest tests
update zero-to-binderhub doc, private registry section

binderhub/app.py

@@ -307,6 +307,16 @@ def _valid_badge_base_url(self, proposal):
         config=True
     )
 
+    @validate('image_prefix')
+    def _valid_image_prefix(self, proposal):
+        image_regex = re.compile(r'^([^\/:]+(?::[0-9]+)?\/)?' +
+                                 r'([_a-zA-Z0-9\-\.]+(?:\/[_a-zA-Z0-9\-\.]+)*)$')
+        if image_regex.match(proposal.value) is None:
+            raise AttributeError("'image_prefix' does not match the expected pattern "+
+                                 "[<registry>[:<port>]/]<repo>")
+
+        return proposal.value
+
     build_memory_request = ByteSpecification(
         0,
         help="""

binderhub/builder.py

@@ -306,7 +306,7 @@ async def get(self, provider_prefix, _unescaped_spec):
         if self.settings['use_registry']:
             for _ in range(3):
                 try:
-                    image_manifest = await self.registry.get_image_manifest(*'/'.join(image_name.split('/')[-2:]).split(':', 1))
+                    image_manifest = await self.registry.get_image_manifest(image_name)
                     image_found = bool(image_manifest)
                     break
                 except HTTPClientError:

binderhub/health.py

@@ -146,9 +146,7 @@ async def check_docker_registry(self):
         # we are only interested in getting a response from the registry, we
         # don't care if the image actually exists or not
         image_name = self.settings["image_prefix"] + "some-image-name:12345"
-        await registry.get_image_manifest(
-            *'/'.join(image_name.split('/')[-2:]).split(':', 1)
-        )
+        await registry.get_image_manifest(image_name)
         return True
 
     async def check_pod_quota(self):

binderhub/registry.py

@@ -185,8 +185,28 @@ def _default_password(self):
             base64.b64decode(b64_auth.encode("utf-8")).decode("utf-8").split(":", 1)[1]
         )
 
-    async def get_image_manifest(self, image, tag):
+    @staticmethod
+    def parse_image_name(name):
+        """Parse a docker image string into (registry, image, tag)"""
+        # name could be "localhost:5000/foo:tag" 
+        # or "gcr.io/project/subrepo/sub/sub/sub:tag" 
+        # or "org/repo:tag" for implicit docker.io
+        registry, _, tagged_image = name.partition("/")
+        if tagged_image and (registry == "localhost" or any(c in registry for c in (".", ":"))):
+            # registry host is specified
+            pass
+        else:
+            # registry not given, use implicit default docker.io registry
+            registry = "docker.io"
+            tagged_image = name
+        image, _, tag = tagged_image.partition(":")
+
+        return registry, image, tag
+
+    async def get_image_manifest(self, name):
         client = httpclient.AsyncHTTPClient()
+        _, image, tag = DockerRegistry.parse_image_name(name)
+
         url = "{}/v2/{}/manifests/{}".format(self.url, image, tag)
         # first, get a token to perform the manifest request
         if self.token_url:

binderhub/tests/test_app.py

@@ -2,10 +2,29 @@
 
 from subprocess import check_output
 import sys
+import pytest
+
+from binderhub.app import BinderHub
+
 
 def test_help():
     check_output([sys.executable, '-m', 'binderhub', '-h'])
 
 def test_help_all():
     check_output([sys.executable, '-m', 'binderhub', '--help-all'])
 
+def test_image_prefix():
+    b = BinderHub()
+
+    prefixes = ["foo/bar", "foo-bar/baz", "foo/bar-", "localhost/foo", "localhost/foo/bar/baz",
+                "localhost:8080/foo/bar/baz", "127.0.0.1/foo", "127.0.0.1:5000/foo/b",
+                "f/o/o/b/a/r/b/a/z", "gcr.io/foo", "my.gcr.io:5000/foo", "foo_bar/baz-",
+                "foo_ba.r/baz-"]
+    for name in prefixes:
+        b.image_prefix = name
+
+    wrong_prefixes = ["foo/bar-baz:", "foo/bar-baz:", "foo/bar-baz:10", "foo/bar/", "/foo/bar", 
+                      "http://localhost/foo/bar"]
+    for name in wrong_prefixes:
+        with pytest.raises(AttributeError):
+            b.image_prefix = name

binderhub/tests/test_registry.py

@@ -113,7 +113,7 @@ async def test_get_image_manifest(tmpdir, request):
         [
             (r"/token", MockTokenHandler, {"test_handle": test_handle}),
             (
-                r"/v2/([^/]+)/manifests/([^/]+)",
+                r"/v2/([a-zA-Z0-9]+(?:/[a-zA-Z0-9]+)*)/manifests/([a-zA-Z0-9]+)",
                 MockManifestHandler,
                 {"test_handle": test_handle},
             ),
@@ -145,5 +145,9 @@ async def test_get_image_manifest(tmpdir, request):
     assert registry.token_url == url + "/token"
     assert registry.username == username
     assert registry.password == password
-    manifest = await registry.get_image_manifest("myimage", "abc123")
-    assert manifest == {"image": "myimage", "tag": "abc123"}
+
+    names = ["myimage:abc123", "localhost/myimage:abc1234", "localhost:8080/myimage:abc3",
+              "192.168.1.1:8080/myimage:abc321", "192.168.1.1:8080/some/repo/myimage:abc3210"]
+    for name in names:
+        manifest = await registry.get_image_manifest(name)
+        assert manifest == {"image": name.split("/", 1)[-1].rsplit(":", 1)[0], "tag": name.rsplit(":", 1)[-1]}

doc/zero-to-binderhub/setup-binderhub.rst

@@ -291,13 +291,18 @@ If you setup your own local registry using
 
 .. important::
 
-    BinderHub assumes that `image_prefix` contains an extra level for the project name such that: `gcr.io/<project-id>/<prefix>-name:tag`.
-    Hence, your `image_prefix` field should be set to: `your-registry.io/<some-project-name>/<prefix>-`.
-    See `this issue <https://github.com/jupyterhub/binderhub/issues/800>`_ for more details.
-
-    `<some-project-name>` can be completely arbitrary and/or made-up.
-    For example, it could be the name you give your BinderHub.
-    Without this extra level, you may find that your BinderHub always rebuilds images instead of pulling them from the registry.
+    BinderHub validates that `image_prefix` matches the following pattern: `[<registry>/]<prefix>`.
+
+    <registry> is optional and defaults to `docker.io`. It may include the server port but does not 
+    include the protocol (http[s]://).
+
+    <prefix> supports any repository depth.
+
+    Examples:
+    - `binder-`
+    - `foo/binder-`
+    - `docker.io/foo/bar/baz/binder-`
+    - `127.0.0.1:5000/binder-`
 
 Install BinderHub
 -----------------