1 files changed, 130 insertions, 0 deletions
diff --git a/gitsnap/snap.py b/gitsnap/snap.py
new file mode 100644
index 0000000..44e32fb
--- /dev/null
+++ b/gitsnap/snap.py
@@ -0,0 +1,130 @@
+import os
+import argparse
+from pathlib import Path
+import datetime
+from functools import wraps
+import collections
+import csv
+import sh
+
+from sh.contrib import git
+import boto3
+
+s3 = boto3.resource('s3')
+
+
+parser = argparse.ArgumentParser()
+subparsers = parser.add_subparsers(dest='cmd', help='git snapshot commands')
+
+parser_backup= subparsers.add_parser('backup', help='backup repositories')
+parser_backup.add_argument('repositories', help='directory with repos')
+
+args = parser.parse_args()
+
+Context = collections.namedtuple('Context',
+                                 'repo bucket prefix bundle repo_name wal')
+
+
+class Wal(object):
+    """WAL writer for server processes"""
+
+    WAL_FILE = os.environ.get('WAL_FILE', 'git-snaphot.wal')
+    wal = None
+    fd = None
+
+    def __init__(self):
+        self.fd = open(self.WAL_FILE, 'a')
+        self.wal = csv.writer(self.fd, quotechar='|', quoting=csv.QUOTE_ALL)
+
+    def __enter__(self):
+        return self
+
+    def __exit__(self, type, value, traceback):
+        self.fd_to_disk()
+        self.fd.close()
+
+    def write(self, row):
+        ts_row = [datetime.datetime.utcnow().timestamp()]
+        ts_row.extend(row)
+        self.wal.writerow(ts_row)
+        self.fd_to_disk()
+
+    def fd_to_disk(self):
+        self.fd.flush()
+        os.fsync(self.fd)
+
+def logit(log_message):
+    def logitargs(func):
+        @wraps(func)
+        def with_logging(ctx, *args, **kwargs):
+            ctx.wal.write([log_message, f'started {ctx.repo_name}'])
+            output = None
+            try:
+                output = func(ctx, *args, **kwargs)
+            except Exception as e:
+                ctx.wal.write([log_message, f'failed {e}'])
+            ctx.wal.write([log_message, f' completed {ctx.repo_name}'])
+            return output
+        return with_logging
+    return logitargs
+
+@logit('s3 object upload')
+def cloud_object(ctx, bundle):
+    obj = s3.Object(ctx.bucket, f'{ctx.prefix}/{bundle.name}')
+    obj.upload_file(str(bundle))
+    return obj
+
+@logit('repo bundle')
+def create_bundle(ctx):
+    # new repo or backup
+    ts = datetime.datetime.utcnow().timestamp()
+    bundle_path = Path(f'{ctx.repo_name}.{ts}.bundle')
+    ctx.repo.bundle('create', bundle_path, '--all')
+    return bundle_path
+
+@logit('repo checkpoint tag')
+def tag_checkpoint(ctx):
+    last_hash = ctx.repo('rev-list', '-n', 1, '--all').strip()
+    ctx.repo.tag('-f', 'CHECKPOINT', last_hash)
+
+@logit('ready for backup')
+def requires_backup(ctx):
+    last_hash = ctx.repo('rev-list', '-n', 1, '--all').strip()
+    # empty repo
+    if not last_hash:
+        return False
+    try:
+        checkpoint = ctx.repo('rev-list', '-n', 1, 'CHECKPOINT').strip()
+    # no checkpoint exists
+    except sh.ErrorReturnCode as e:
+        return True
+    # flip truthy
+    return last_hash != checkpoint
+
+def run_restore(bundle):
+    pass
+
+def run_backup(ctx):
+    if requires_backup(ctx):
+        bundle_path = create_bundle(ctx)
+        obj = cloud_object(ctx, bundle_path)
+        tag_checkpoint(ctx)
+
+def run_backups(base):
+    repo_base_path = Path(base)
+    with Wal() as wal:
+        for repo_path in repo_base_path.glob('*.git'):
+            ctx = Context(
+                repo=git.bake(f'--git-dir={repo_path}/'),
+                repo_name=repo_path.name.split('.')[0],
+                bucket='privategit',
+                prefix='2',
+                bundle=None,
+                wal=wal
+            )
+            run_backup(ctx)
+
+if args.cmd == 'backup':
+    run_backups(args.repositories)
+elif args.cmd == 'restore':
+    run_restore(args.bundle)