Merge pull request #14 from tilezen/zerebubuth/util-log-tail

Add utility to watch CW logs from TPS instance.

utils/cwtail.py

@@ -0,0 +1,48 @@
+import boto3
+import time
+import argparse
+
+
+parser = argparse.ArgumentParser(
+    description="""
+Stream the latest lines from a log stream by ingestion time. This acts a bit
+like "tailing" a log file. It's by ingestion time rather than event time, as
+the TPS logs don't seem to get the right event time right now.
+""")
+parser.add_argument('group', help='Name of the log group for TPS logs')
+parser.add_argument('--stream', help='Name of log stream. Optional, defaults '
+                    'to the stream in the group with the most recent events')
+parser.add_argument('--interval', default=60, type=int,
+                    help='Interval between log updates.')
+args = parser.parse_args()
+
+logs = boto3.client('logs')
+log_group = args.group
+log_stream = args.stream
+if log_stream is None:
+    response = logs.describe_log_streams(
+        logGroupName=log_group,
+        orderBy='LastEventTime',
+        descending=True,
+        limit=1,
+    )
+
+    streams = response['logStreams']
+    assert streams
+    log_stream = streams[0]['logStreamName']
+
+last_time = None
+while True:
+    response = logs.get_log_events(
+        logGroupName=log_group, logStreamName=log_stream, limit=150,
+        startFromHead=False)
+
+    for event in response['events']:
+        ingest_time = event['ingestionTime']
+        # any integer is greater than None, so we don't need to check for
+        # last_time is None
+        if ingest_time > last_time:
+            print(event['message'])
+            last_time = ingest_time
+
+    time.sleep(args.interval)