BuildExecutor.identifier for BinderHub /version endpoint

Author: manics

binderhub/app.py

@@ -869,6 +869,9 @@ def initialize(self, *args, **kwargs):
 
         launch_quota = self.launch_quota_class(parent=self, executor=self.executor)
 
+        # Construct a Builder so that we can extract the version string to pass to the
+        # /version handler
+        temporary_builder = self.build_class(parent=self)
         self.tornado_settings.update(
             {
                 "log_function": log_request,
@@ -881,6 +884,7 @@ def initialize(self, *args, **kwargs):
                 "build_token_check_origin": self.build_token_check_origin,
                 "build_token_secret": self.build_token_secret,
                 "build_token_expires_seconds": self.build_token_expires_seconds,
+                "builder_identifier": temporary_builder.identifier,
                 "pod_quota": self.pod_quota,
                 "per_repo_quota": self.per_repo_quota,
                 "per_repo_quota_higher": self.per_repo_quota_higher,

binderhub/base.py

@@ -247,7 +247,7 @@ async def get(self):
         self.write(
             json.dumps(
                 {
-                    "builder": self.settings["build_image"],
+                    "builder": self.settings["builder_identifier"],
                     "binderhub": binder_version,
                 }
             )

binderhub/build.py

@@ -101,6 +101,15 @@ class BuildExecutor(LoggingConfigurable):
         config=True,
     )
 
+    identifier = Unicode(
+        "",
+        help=(
+            "Identifier or other metadata for the builder e.g. repo2docker version. "
+            "This is included in the BinderHub version endpoint"
+        ),
+        config=True,
+    )
+
     def __init__(self, **kwargs):
         super().__init__(**kwargs)
         self.main_loop = IOLoop.current()
@@ -239,6 +248,10 @@ def _default_namespace(self):
         config=True,
     )
 
+    @default("identifier")
+    def _default_identifier(self):
+        return self.build_image
+
     docker_host = Unicode(
         "/var/run/docker.sock",
         help=(