backend: Use th backup URL in backup-cli and add snapshot type to FileBackend

backup/backup-cli

@@ -1,5 +1,5 @@
 #!/usr/bin/env python3
-from backup import FileBackend
+from backup import FileBackend, get_backend
 import os
 import click
 import json
@@ -7,10 +7,10 @@ import json
 
 @click.command()
 @click.argument("lightning-dir", type=click.Path(exists=True))
-@click.argument("backup-dir", type=click.Path(exists=True))
-def init(lightning_dir, backup_dir):
-    destination = 'file://' + os.path.join(backup_dir, 'backup.dbak')
-    backend = FileBackend(destination)
+@click.argument("backend-url")
+def init(lightning_dir, backend_url):
+    destination = backend_url
+    backend = get_backend(destination)
     backend.version, backend.prev_version = 0, 0
     backend.offsets = [512, 0]
     backend.version_count = 0
@@ -23,6 +23,8 @@ def init(lightning_dir, backup_dir):
             'backend_url': destination,
         }))
 
+    # TODO Take a snapshot
+
     print("Initialized backup backend {destination}, you can now start c-lightning".format(
         destination=destination,
     ))

backup/backup.py

@@ -132,10 +132,11 @@ class FileBackend(Backend):
         with open(self.url.path, 'ab') as f:
             f.seek(self.offsets[0])
             f.write(length)
+            f.write(typ)
             f.write(payload)
             self.prev_version, self.offsets[1] = self.version, self.offsets[0]
             self.version = entry.version
-            self.offsets[0] += 4 + len(payload)
+            self.offsets[0] += 5 + len(payload)
         self.write_metadata()
 
         return True
@@ -163,6 +164,15 @@ def resolve_backend_class(backend_url):
     return backend_cl
 
 
+def get_backend(destination):
+    backend_cl = resolve_backend_class(destination)
+    if backend_cl is None:
+        raise ValueError("No backend implementation found for {destination}".format(
+            destination=destination,
+        ))
+    return backend_cl(destination)
+
+
 def abort(reason: str) -> None:
     plugin.log(reason)
     plugin.rpc.stop()
@@ -246,12 +256,7 @@ def on_init(options: Mapping[str, str], plugin: Plugin, **kwargs):
     if not plugin.db_path.startswith('sqlite3'):
         abort("The backup plugin only works with the sqlite3 database.")
 
-    # Let's initialize the backed. First we need to figure out which backend to use.
-    backend_cl = resolve_backend_class(destination)
-    if backend_cl is None:
-        abort("Could not find a backend for scheme {p.scheme}".format(p=p))
-
-    plugin.backend = backend_cl(destination)
+    plugin.backend = get_backend(destination)
     if not plugin.backend.initialize():
         abort("Could not initialize the backup {}, please use 'backup-cli' to initialize the backup first.".format(destination))
 

backup/test_backup.py

@@ -12,20 +12,13 @@ cli_path = os.path.join(os.path.dirname(__file__), "backup-cli")
 
 
 def test_start(node_factory, directory):
-    bdest = os.path.join(directory, 'lightning-1', 'backup.dbak')
-    opts = {
-        'plugin': plugin_path,
-        'backup-destination': 'file://' + bdest,
-        }
-
-    subprocess.check_call([cli_path, "init", directory, directory])
     bpath = os.path.join(directory, 'lightning-1', 'regtest')
-    bdest = os.path.join(bpath, 'backup.dbak')
+    bdest = 'file://' + os.path.join(bpath, 'backup.dbak')
     os.makedirs(bpath)
-    subprocess.check_call([cli_path, "init", bpath, bpath])
+    subprocess.check_call([cli_path, "init", bpath, bdest])
     opts = {
         'plugin': plugin_path,
-        'backup-destination': 'file://' + bdest,
+        'backup-destination': bdest,
         }
     l1 = node_factory.get_node(options=opts, cleandir=False)
 
@@ -48,12 +41,12 @@ def test_tx_abort(node_factory, directory):
 
     """
     bpath = os.path.join(directory, 'lightning-1', 'regtest')
-    bdest = os.path.join(bpath, 'backup.dbak')
+    bdest = 'file://' + os.path.join(bpath, 'backup.dbak')
     os.makedirs(bpath)
-    subprocess.check_call([cli_path, "init", bpath, bpath])
+    subprocess.check_call([cli_path, "init", bpath, bdest])
     opts = {
         'plugin': plugin_path,
-        'backup-destination': 'file://' + bdest,
+        'backup-destination': bdest,
         }
     l1 = node_factory.get_node(options=opts, cleandir=False)
     l1.stop()
@@ -78,12 +71,12 @@ def test_failing_restore(nf, directory):
 
     """
     bpath = os.path.join(directory, 'lightning-1', 'regtest')
-    bdest = os.path.join(bpath, 'backup.dbak')
+    bdest = 'file://' + os.path.join(bpath, 'backup.dbak')
     os.makedirs(bpath)
-    subprocess.check_call([cli_path, "init", bpath, bpath])
+    subprocess.check_call([cli_path, "init", bpath, bdest])
     opts = {
         'plugin': plugin_path,
-        'backup-destination': 'file://' + bdest,
+        'backup-destination': bdest,
         }
     l1 = node_factory.get_node(options=opts, cleandir=False)
     l1.stop()
@@ -103,12 +96,12 @@ def test_intermittent_backup(node_factory, directory):
 
     """
     bpath = os.path.join(directory, 'lightning-1', 'regtest')
-    bdest = os.path.join(bpath, 'backup.dbak')
+    bdest = 'file://' + os.path.join(bpath, 'backup.dbak')
     os.makedirs(bpath)
-    subprocess.check_call([cli_path, "init", bpath, bpath])
+    subprocess.check_call([cli_path, "init", bpath, bdest])
     opts = {
         'plugin': plugin_path,
-        'backup-destination': 'file://' + bdest,
+        'backup-destination': bdest,
         }
     l1 = node_factory.get_node(options=opts, cleandir=False)