Add support for different kernel specs to kernels REST API

IPython/html/services/kernels/handlers.py

@@ -27,8 +27,16 b' class MainKernelHandler(IPythonHandler):'
     @web.authenticated
     @json_errors
     def post(self):
+        model = self.get_json_body()
+        if model is None:
+            raise web.HTTPError(400, "No JSON data provided")
+        try:
+            name = model['name']
+        except KeyError:
+            raise web.HTTPError(400, "Missing field in JSON data: name")
+
         km = self.kernel_manager
-        kernel_id = km.start_kernel()
+        kernel_id = km.start_kernel(kernel_name=name)
         model = km.kernel_model(kernel_id)
         location = url_path_join(self.base_url, 'api', 'kernels', kernel_id)
         self.set_header('Location', url_escape(location))

IPython/html/services/kernels/kernelmanager.py

@@ -72,8 +72,8 b' class MappingKernelManager(MultiKernelManager):'
             os_path = os.path.dirname(os_path)
         return os_path
 
-    def start_kernel(self, kernel_id=None, path=None, **kwargs):
-        """Start a kernel for a session an return its kernel_id.
+    def start_kernel(self, kernel_id=None, path=None, kernel_name='python', **kwargs):
+        """Start a kernel for a session and return its kernel_id.
 
         Parameters
         ----------
@@ -84,12 +84,16 b' class MappingKernelManager(MultiKernelManager):'
         path : API path
             The API path (unicode, '/' delimited) for the cwd.
             Will be transformed to an OS path relative to root_dir.
+        kernel_name : str
+            The name identifying which kernel spec to launch. This is ignored if
+            an existing kernel is returned, but it may be checked in the future.
         """
         if kernel_id is None:
             kwargs['extra_arguments'] = self.kernel_argv
             if path is not None:
                 kwargs['cwd'] = self.cwd_for_path(path)
-            kernel_id = super(MappingKernelManager, self).start_kernel(**kwargs)
+            kernel_id = super(MappingKernelManager, self).start_kernel(
+                                            kernel_name=kernel_name, **kwargs)
             self.log.info("Kernel started: %s" % kernel_id)
             self.log.debug("Kernel args: %r" % kwargs)
             # register callback for failed auto-restart
@@ -111,7 +115,8 b' class MappingKernelManager(MultiKernelManager):'
         """Return a dictionary of kernel information described in the
         JSON standard model."""
         self._check_kernel_id(kernel_id)
-        model = {"id":kernel_id}
+        model = {"id":kernel_id,
+                 "name": self._kernels[kernel_id].kernel_name}
         return model
 
     def list_kernels(self):

IPython/html/services/kernels/tests/test_kernels_api.py

@@ -1,6 +1,6 b''
 """Test the kernels service API."""
 
-
+import json
 import requests
 
 from IPython.html.utils import url_path_join
@@ -30,8 +30,9 b' class KernelAPI(object):'
     def get(self, id):
         return self._req('GET', id)
 
-    def start(self):
-        return self._req('POST', '')
+    def start(self, name='python'):
+        body = json.dumps({'name': name})
+        return self._req('POST', '', body)
 
     def shutdown(self, id):
         return self._req('DELETE', id)
@@ -69,6 +70,7 b' class KernelAPITest(NotebookTestBase):'
         self.assertEqual(r.status_code, 200)
         assert isinstance(r.json(), list)
         self.assertEqual(r.json()[0]['id'], kern1['id'])
+        self.assertEqual(r.json()[0]['name'], kern1['name'])
 
         # create another kernel and check that they both are added to the
         # list of kernels from a GET request
@@ -89,6 +91,7 b' class KernelAPITest(NotebookTestBase):'
         self.assertEqual(r.headers['Location'], '/api/kernels/'+kern2['id'])
         rekern = r.json()
         self.assertEqual(rekern['id'], kern2['id'])
+        self.assertEqual(rekern['name'], kern2['name'])
 
     def test_kernel_handler(self):
         # GET kernel with given id

IPython/kernel/multikernelmanager.py

@@ -92,7 +92,7 b' class MultiKernelManager(LoggingConfigurable):'
     def __contains__(self, kernel_id):
         return kernel_id in self._kernels
 
-    def start_kernel(self, **kwargs):
+    def start_kernel(self, kernel_name='python', **kwargs):
         """Start a new kernel.
 
         The caller can pick a kernel_id by passing one in as a keyword arg,
@@ -111,7 +111,7 b' class MultiKernelManager(LoggingConfigurable):'
         # including things like its transport and ip.
         km = self.kernel_manager_factory(connection_file=os.path.join(
                     self.connection_dir, "kernel-%s.json" % kernel_id),
-                    parent=self, autorestart=True, log=self.log
+                    parent=self, autorestart=True, log=self.log, kernel_name=kernel_name,
         )
         km.start_kernel(**kwargs)
         self._kernels[kernel_id] = km