diff --git a/actions.yaml b/actions.yaml
index 3f8e5dfe..67fe4c88 100644
--- a/actions.yaml
+++ b/actions.yaml
@@ -214,3 +214,15 @@ pool-get:
       description: Any valid Ceph key from http://docs.ceph.com/docs/master/rados/operations/pools/#get-pool-values
   required: [key, pool-name]
   additionalProperties: false
+crushmap-update:
+  description: |
+    Apply a json crushmap definition.  This will throw away the existing
+    ceph crushmap and apply the new definition.  Use with extreme caution.
+    WARNING - This function is extremely dangerous if misused. It can very
+    easily break your cluster in unexpected ways.
+  params:
+    map:
+      type: string
+      description: The json crushmap blob
+  required: [map]
+  additionalProperties: false
diff --git a/actions/crushmap-update b/actions/crushmap-update
new file mode 120000
index 00000000..af530e0d
--- /dev/null
+++ b/actions/crushmap-update
@@ -0,0 +1 @@
+crushmap-update.py
\ No newline at end of file
diff --git a/actions/crushmap-update.py b/actions/crushmap-update.py
new file mode 100755
index 00000000..d90e50bf
--- /dev/null
+++ b/actions/crushmap-update.py
@@ -0,0 +1,46 @@
+#!/usr/bin/python
+#
+# Copyright 2016 Canonical Ltd
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#  http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+import base64
+from charmhelpers.core.hookenv import action_get, action_fail
+from subprocess import check_output, CalledProcessError, PIPE, Popen
+
+
+def update_crushmap():
+    try:
+        encoded_text = action_get("map")
+        json_map = base64.b64decode(encoded_text)
+        try:
+            # This needs json_map passed to it from stdin
+            crushtool = Popen(
+                ["crushtool", "-o", "compiled_crushmap", "-m", "compile"],
+                stdin=PIPE)
+            crushtool_stdout, crushtool_stderr = crushtool.communicate(
+                input=json_map)
+            if crushtool_stderr is not None:
+                action_fail(
+                    "Failed to compile json: {}".format(crushtool_stderr))
+            check_output(
+                ["ceph", "osd", "setcrushmap", "-i", "compiled_crushmap"])
+        except (CalledProcessError, OSError) as err2:
+            action_fail("Crush compile or load failed with error: {}".format(
+                err2.output))
+    except TypeError as err:
+        action_fail(
+            "Unable to base64 decode: {}. Error: {}".format(encoded_text, err))
+
+
+if __name__ == '__main__':
+    update_crushmap()