commands: prepare ctdb commands for using cluster meta objects

This change prepares the ctdb related commands in sambacc for using
different paths or, eventually, different uris for the cluster metadata
state data. Currently, this must still be a file but the file can be
specified by path `/foo/bar/baz` or uri style `file:///foo/bar/baz`.

The CLI now constructs a ClusterMeta object and passes it to the library
functions rather than passing a path.

Signed-off-by: John Mulligan <[email protected]>

Author: phlogistonjohn

sambacc/commands/ctdb.py

@@ -23,6 +23,8 @@
 import typing
 
 from sambacc import ctdb
+from sambacc import jfile
+from sambacc.simple_waiter import Waiter
 
 from .cli import best_waiter, commands, Context, Fail
 
@@ -86,6 +88,13 @@ def _ctdb_general_node_args(parser: argparse.ArgumentParser) -> None:
         "--persistent-path",
         help="Path to a persistent path for storing nodes file",
     )
+    parser.add_argument(
+        "--metadata-source",
+        help=(
+            "Specify location of cluster metadata state-tracking object."
+            " This can be a file path or a URI-style identifier."
+        ),
+    )
 
 
 def _ctdb_set_node_args(parser: argparse.ArgumentParser) -> None:
@@ -101,8 +110,11 @@ class NodeParams:
     node_number: typing.Optional[int] = None
     hostname: typing.Optional[str] = None
     persistent_path: str = ""
-    nodes_json: str = ""
+    _nodes_json: str = ""
+    _cluster_meta_uri: str = ""
     _ip_addr: typing.Optional[str] = None
+    _cluster_meta_obj: typing.Optional[ctdb.ClusterMeta] = None
+    _waiter_obj: typing.Optional[Waiter] = None
 
     def __init__(self, ctx: Context):
         self._ctx = ctx
@@ -112,7 +124,12 @@ def __init__(self, ctx: Context):
         self.persistent_path = ctx.cli.persistent_path
         if self.persistent_path is None:
             self.persistent_path = ccfg["nodes_path"]
-        self.nodes_json = ccfg["nodes_json"]
+        # nodes_json will now only be in the ctdb config section if it has been
+        # specified by the user.
+        self._nodes_json = ccfg.get("nodes_json") or ""
+        # cluster_meta_uri can be a uri-ish string or path. It will be set with
+        # a default value by the config even if there's no user supplied value.
+        self._cluster_meta_uri = ccfg.get("cluster_meta_uri") or ""
 
         self.hostname = ctx.cli.hostname
         if ctx.cli.node_number is not None:
@@ -145,7 +162,7 @@ def node_ip_addr(self) -> str:
         return self._ip_addr
 
     @property
-    def identity(self):
+    def identity(self) -> str:
         # this could be extended to use something like /etc/machine-id
         # or whatever in the future.
         if self.hostname:
@@ -156,6 +173,49 @@ def identity(self):
             # the dashes make this an invalid dns name
             return "-unknown-"
 
+    @property
+    def cluster_meta_uri(self) -> str:
+        """Return a cluster meta uri value."""
+        values = (
+            # cli takes highest precedence
+            self._ctx.cli.metadata_source,
+            # _nodes_json should only be set if user set it using the old key
+            self._nodes_json,
+            # default or customized value on current key
+            self._cluster_meta_uri,
+        )
+        for uri in values:
+            if uri:
+                return uri
+        raise ValueError("failed to determine cluster_meta_uri")
+
+    def _cluster_meta_init(self) -> None:
+        uri = self.cluster_meta_uri
+        # it'd be nice to re-use the opener infrastructure here but openers
+        # don't do file modes the way we need for JSON state file or do
+        # writable file types in the url_opener (urllib wrapper). For now, just
+        # manually handle the string.
+        if uri.startswith("file:"):
+            path = uri.split(":", 1)[-1]
+        else:
+            path = uri
+        if path.startswith("/"):
+            path = "/" + path.rstrip("/")  # ensure one leading /
+        self._cluster_meta_obj = jfile.ClusterMetaJSONFile(path)
+        self._waiter_obj = best_waiter(path)
+
+    def cluster_meta(self) -> ctdb.ClusterMeta:
+        if self._cluster_meta_obj is None:
+            self._cluster_meta_init()
+        assert self._cluster_meta_obj is not None
+        return self._cluster_meta_obj
+
+    def cluster_meta_waiter(self) -> Waiter:
+        if self._waiter_obj is None:
+            self._cluster_meta_init()
+        assert self._waiter_obj is not None
+        return self._waiter_obj
+
 
 @commands.command(name="ctdb-migrate", arg_func=_ctdb_migrate_args)
 def ctdb_migrate(ctx: Context) -> None:
@@ -180,21 +240,21 @@ def ctdb_set_node(ctx: Context) -> None:
     expected_pnn = np.node_number
 
     try:
-        ctdb.refresh_node_in_statefile(
-            np.identity,
-            np.node_ip_addr,
-            int(expected_pnn or 0),
-            path=np.nodes_json,
+        ctdb.refresh_node_in_cluster_meta(
+            cmeta=np.cluster_meta(),
+            identity=np.identity,
+            node=np.node_ip_addr,
+            pnn=int(expected_pnn or 0),
         )
         return
     except ctdb.NodeNotPresent:
         pass
 
-    ctdb.add_node_to_statefile(
-        np.identity,
-        np.node_ip_addr,
-        int(expected_pnn or 0),
-        path=np.nodes_json,
+    ctdb.add_node_to_cluster_meta(
+        cmeta=np.cluster_meta(),
+        identity=np.identity,
+        node=np.node_ip_addr,
+        pnn=int(expected_pnn or 0),
         in_nodes=(expected_pnn == 0),
     )
     if expected_pnn == 0:
@@ -214,14 +274,14 @@ def ctdb_manage_nodes(ctx: Context) -> None:
     _ctdb_ok()
     np = NodeParams(ctx)
     expected_pnn = np.node_number or 0
-    waiter = best_waiter(np.nodes_json)
+    waiter = np.cluster_meta_waiter()
 
     errors = 0
     while True:
         try:
-            ctdb.manage_nodes(
-                expected_pnn,
-                nodes_json=np.nodes_json,
+            ctdb.monitor_cluster_meta_updates(
+                cmeta=np.cluster_meta(),
+                pnn=expected_pnn,
                 real_path=np.persistent_path,
                 pause_func=waiter.wait,
             )
@@ -246,13 +306,12 @@ def ctdb_must_have_node(ctx: Context) -> None:
     _ctdb_ok()
     np = NodeParams(ctx)
     expected_pnn = np.node_number or 0
-    waiter = best_waiter(np.nodes_json)
+    waiter = np.cluster_meta_waiter()
 
     while True:
-        if ctdb.pnn_in_nodes(
-            expected_pnn,
-            nodes_json=np.nodes_json,
-            real_path=np.persistent_path,
+        if ctdb.pnn_in_cluster_meta(
+            cmeta=np.cluster_meta(),
+            pnn=expected_pnn,
         ):
             return
         _logger.info("node not yet ready")