Changes to get IPython 3 to list kernels based on conda environments (requires conda on the path, and for the post-link.sh to be executed for each IPython enabled environment). This is a hack, and I expect there is a better way of doing this...

ipython.patch

diff --git IPython/kernel/kernelspec.py IPython/kernel/kernelspec.py
index 0df16c7..d2df218 100644
--- IPython/kernel/kernelspec.py
+++ IPython/kernel/kernelspec.py
@@ -1,7 +1,9 @@
 import io
 import json
+import glob
 import os
 import shutil
+import subprocess
 import sys
 
 pjoin = os.path.join
@@ -22,9 +24,26 @@
     SYSTEM_KERNEL_DIRS = ["/usr/share/jupyter/kernels",
                           "/usr/local/share/jupyter/kernels",
                          ]
-    
+
+def conda_envs():
+    # Get conda off the path.
+    conda = subprocess.check_output(['which', 'conda']).strip()
+    if not os.path.exists(conda):
+        return []
+
+    envs = subprocess.check_output([conda, 'env', 'list', '--json'])
+
+    envs = json.loads(envs)['envs']
+    return [os.path.join(env, 'share', 'jupyter', 'kernels') for env in envs]
+
+
+# Put all centrally installed environments in the kernel path.
+_CENTRAL_ENVS = '/opt/ukmo/iris/envs/*/share/jupyter/kernels/'
+
+
 NATIVE_KERNEL_NAME = 'python3' if PY3 else 'python2'
 
+
 def _pythonfirst(s):
     "Sort key function that will put strings starting with 'python' first."
     if s == NATIVE_KERNEL_NAME:
@@ -131,10 +150,14 @@ def _native_kernel_resource_dir(self):
     def find_kernel_specs(self):
         """Returns a dict mapping kernel names to resource directories."""
         d = {}
-        for kernel_dir in self.kernel_dirs:
+        # Dynamically update the potential kernel directories.
+        self.kernel_dirs.extend(conda_envs())
+        self.kernel_dirs.extend(glob.glob(_CENTRAL_ENVS))
+        for kernel_dir in set(self.kernel_dirs):
             d.update(_list_kernels_in(kernel_dir))
 
-        d[NATIVE_KERNEL_NAME] = self._native_kernel_resource_dir
+        # Disable the "Python 2" or "Python 3" spec.
+        #d[NATIVE_KERNEL_NAME] = self._native_kernel_resource_dir
         if self.whitelist:
             # filter if there's a whitelist
             d = {name:spec for name,spec in d.items() if name in self.whitelist}

post-link.sh

#!/usr/bin/env bash

# Create a kernel for this env

ENV_NAME=$(basename ${PREFIX})

echo "Creating kernel for the \"${ENV_NAME}\" env." > $PREFIX/.messages.txt

mkdir -p $PREFIX/share/jupyter/kernels/env_${ENV_NAME}
cat > $PREFIX/share/jupyter/kernels/env_${ENV_NAME}/kernel.json <<EOF
{
 "display_name": "ENV: ${ENV_NAME}",
 "language": "python",
 "codemirror_mode": {
  "version": 3,
  "name": "ipython"
 },
 "argv": [
  "${PREFIX}/bin/python",
  "-c",
  "from IPython.kernel.zmq.kernelapp import main; main()",
  "-f",
  "{connection_file}"
 ]
}
EOF