feat: implement support for the cephfs-share relation

This allows using the `cephfs-client` charm to connect
to the CephFS share without having to do a manual
setup.

Change-Id: I1823dc0624c66232cd282ed098c7a58ea7456fa8

.gitignore

@@ -1,10 +1,10 @@
 build
 .tox
 layers
-interfaces
 .testrepository
 __pycache__
 *.pyc
 .idea
 .stestr
 *.charm
+.vscode

interfaces/cephfs_share/interface.yaml

@@ -0,0 +1,3 @@
+name: cephfs_share
+summary: CephFS Share provider interface
+version: 1

interfaces/cephfs_share/provides.py

@@ -0,0 +1,99 @@
+from charms.reactive import scopes, when, set_flag, clear_flag
+from charms.reactive.endpoints import Endpoint
+
+from charmhelpers.core import hookenv
+
+from typing import Iterable, Dict, Set
+
+import json
+
+class _Transaction:
+    """Store transaction information between data mappings."""
+
+    def __init__(self, added: Set, changed: Set, deleted: Set):
+        self.added: Set = added
+        self.changed: Set = changed
+        self.deleted: Set = deleted
+
+def _eval(relation) -> _Transaction:
+    """Evaluate the difference between data in an integration changed databag.
+
+    Args:
+        relation: Relation with the written data.
+
+    Returns:
+        _Transaction:
+            Transaction info containing the added, deleted, and changed
+            keys from the relation databag.
+    """
+    # Retrieve the old data from the data key in the unit databag.
+    old_data = json.loads(relation.to_publish_raw.get("cache", "{}"))
+    # Retrieve the new data from the relation integration databag.
+    new_data = {
+        key: value for key, value in relation.received_app.items() if key != "cache"
+    }
+    # These are the keys that were added to the databag and triggered this event.
+    added = new_data.keys() - old_data.keys()
+    # These are the keys that were removed from the databag and triggered this event.
+    deleted = old_data.keys() - new_data.keys()
+    # These are the keys that were added or already existed in the databag, but had their values changed.
+    changed = added.union(
+        {key for key in old_data.keys() & new_data.keys() if old_data[key] != new_data[key]}
+    )
+    # Convert the new_data to a serializable format and save it for a next diff check.
+    relation.to_publish_raw.update({
+        "cache": json.dumps(new_data)
+    })
+
+    # Return the transaction with all possible changes.
+    return _Transaction(added, changed, deleted)
+
+class CephFSProvides(Endpoint):
+
+    @when('endpoint.{endpoint_name}.changed')
+    def changed(self):
+        if hookenv.is_leader():
+            for relation in self.relations:
+                transaction = _eval(relation)
+                if "name" in transaction.added:
+                    set_flag(self.expand_name('{endpoint_name}.available'))
+
+    def manage_flags(self):
+        if not self.is_joined:
+            clear_flag(
+                self.expand_name('{endpoint_name}.available')
+            )
+
+    def set_share(self, share_info: Dict, auth_info: Dict) -> None:
+        """Set info for mounting a CephFS share.
+
+        Args:
+            relation:
+            share_info: Dictionary with the information required to mount the CephFS share.
+                - fsid: ID of the Ceph cluster.
+                - name: Name of the exported Ceph filesystem.
+                - path: Exported path of the Ceph filesystem.
+                - monitor_hosts: Address list of the available Ceph MON nodes.
+            auth_info: Dictionary with the information required to authenticate against the Ceph cluster.
+                - username: Name of the user authorized to access the Ceph filesystem.
+                - key: Cephx key for the authorized user.
+
+        Notes:
+            Only the application leader unit can set the CephFS share data.
+        """
+        if hookenv.is_leader():
+            share_info = json.dumps({
+                    'fsid': share_info['fsid'],
+                    'name': share_info['name'],
+                    'path': share_info['path'],
+                    'monitor_hosts': share_info['monitor_hosts']
+                })
+            auth_info = json.dumps({
+                    'username': auth_info['username'],
+                    'key': auth_info['key']
+                })
+            for relation in self.relations:
+                relation.to_publish_app_raw.update({
+                    "share_info": share_info,
+                    "auth": f"plain:{auth_info}",
+                })

src/layer.yaml

@@ -1,4 +1,4 @@
-includes: ['layer:ceph', 'interface:ceph-mds']
+includes: ['layer:ceph', 'interface:ceph-mds', 'interface:cephfs_share']
 options:
   basic:
     use_venv: True

src/metadata.yaml

@@ -19,5 +19,9 @@ subordinate: false
 requires:
   ceph-mds:
     interface: ceph-mds
+provides:
+  cephfs-share:
+    interface: cephfs_share
+
 extra-bindings:
   public:

src/reactive/ceph_fs.py

@@ -17,8 +17,10 @@ from charms import reactive
 import charmhelpers.core as ch_core
 
 from charmhelpers.core.hookenv import (
-    service_name,
+    service_name, application_name,
+    is_leader,
     config)
+from charmhelpers.contrib.storage.linux import ceph
 
 import charms_openstack.bus
 import charms_openstack.charm as charm
@@ -205,3 +207,37 @@ def storage_ceph_connected(ceph):
             weight=metadata_weight,
             app_name=ceph_mds.ceph_pool_app_name)
     ceph_mds.request_cephfs(service, extra_pools=extra_pools)
+    # Must have a current request thanks to the call above
+    rq = ceph_mds.get_current_request()
+    rq.add_op({
+        'op': 'create-cephfs-client',
+        'fs_name': service,
+        'client_id': '{}-client'.format(service),
+        'path': "/",
+        'perms': 'rw',
+    })
+    ceph_mds.send_request_if_needed(rq)
+
+
+@reactive.when_none('charm.paused', 'run-default-update-status')
+@reactive.when('cephfs.configured', 'ceph-mds.pools.available',
+               'cephfs-share.available')
+def cephfs_share_available():
+    cephfs_share = reactive.endpoint_from_flag('cephfs-share.available')
+    ceph_mds = reactive.endpoint_from_flag('ceph-mds.pools.available')
+    service = application_name()
+    if is_leader():
+        response_key = ceph.get_broker_rsp_key()
+        # After the `create-cephfs-client` request completes, the
+        # databag must contain the generated key for that user.
+        key = ceph_mds.all_joined_units.received[response_key]["key"]
+
+        cephfs_share.set_share(share_info={
+            "fsid": ceph_mds.fsid,
+            "name": service,
+            "path": "/",
+            "monitor_hosts": ceph_mds.mon_hosts(),
+        }, auth_info={
+            "username": '{}-client'.format(service),
+            "key": key
+        })

unit_tests/test_reactive_ceph_fs.py

@@ -32,12 +32,27 @@ class TestRegisteredHooks(test_utils.TestRegisteredHooks):
         ]
         hook_set = {
             'when': {
-                'config_changed': ('ceph-mds.pools.available',),
-                'storage_ceph_connected': ('ceph-mds.connected',),
+                'config_changed': (
+                    'ceph-mds.pools.available',
+                ),
+                'storage_ceph_connected': (
+                    'ceph-mds.connected',
+                ),
+                'cephfs_share_available': (
+                    'cephfs.configured',
+                    'ceph-mds.pools.available',
+                    'cephfs-share.available',
+                ),
             },
             'when_none': {
-                'config_changed': ('charm.paused',
-                                   'run-default-update-status',),
+                'config_changed': (
+                    'charm.paused',
+                    'run-default-update-status',
+                ),
+                'cephfs_share_available': (
+                    'charm.paused',
+                    'run-default-update-status',
+                ),
             },
         }
         # test that the hooks were registered via the reactive.ceph_fs module
@@ -83,3 +98,55 @@ class TestCephFSHandlers(test_utils.PatchHelper):
         handlers.config_changed()
         self.target.install.assert_called_once_with()
         self.target.upgrade_if_available.assert_called_once_with([ceph_mds])
+
+    def test_cephfs_share_available(self):
+        self.patch_object(handlers.reactive, 'endpoint_from_flag')
+        handlers.ch_core.hookenv.application_name.return_value = "ceph-fs"
+        handlers.ceph.get_broker_rsp_key.return_value = 'broker-rsp-ceph-fs-0'
+
+        ceph_mds = mock.MagicMock()
+        ceph_mds.fsid = "354ca7c4-f10d-11ee-93f8-1f85f87b7845"
+        ceph_mds.mon_hosts.return_value = [
+            "10.5.0.80:6789", "10.5.2.23:6789", "10.5.2.17:6789"]
+        ceph_mds.all_joined_units.received = {
+            "auth": "cephx",
+            "broker-rsp-ceph-fs-0": {
+                "exit-code": 0,
+                "key": "AQDvOE5mUfBIKxAAYT73/v7NzwWx2ovLB4nnOg==",
+                "request-id": "22dd9c7d8c7d392d44866b35219a654006fd90f0"},
+            "ceph-public-address": "10.143.60.15",
+            "fsid": "354ca7c4-f10d-11ee-93f8-1f85f87b7845",
+            "juju-2ffa43-1_mds_key":
+                "AQDwOE5mmkQ1LBAAVrx4OXWwWM+XmK/KjnJcdA==",
+        }
+
+        cephfs_share = mock.MagicMock()
+
+        def mock_eff(flag):
+            if flag == "ceph-mds.pools.available":
+                return ceph_mds
+            elif flag == "cephfs-share.available":
+                return cephfs_share
+            else:
+                raise Exception("invalid input")
+
+        self.endpoint_from_flag.side_effect = mock_eff
+
+        handlers.cephfs_share_available()
+
+        cephfs_share.set_share.assert_called_once_with(
+            share_info={
+                "fsid": "354ca7c4-f10d-11ee-93f8-1f85f87b7845",
+                "name": "ceph-fs",
+                "path": "/",
+                "monitor_hosts": [
+                    "10.5.0.80:6789",
+                    "10.5.2.23:6789",
+                    "10.5.2.17:6789"
+                ],
+            },
+            auth_info={
+                "username": "ceph-fs-client",
+                "key": "AQDvOE5mUfBIKxAAYT73/v7NzwWx2ovLB4nnOg=="
+            }
+        )