Elastic Beanstalk CloudWatch Log streaming stops working – How to debug

Question

My Elastic Beanstalk environment is stopping streaming node.js events to CloudWatch Logs. Streaming works fine for a view minutes on a new instance. After a view minutes no more logs show up in CloudWatch.

I set up AWS Elastic Beanstalk to stream logs to CloudWatch under Configuration > Software Configuration > CloudWatch Logs > Log Streaming (true). I deactivated log streaming and reactivated it as a test. Taking a look at cloudwatch

• Last eb-activity log is about 10 minutes old
• Error log is not available (on neither of the instances)
• nginx/access.log is a view seconds old
• nodejs.log is about an hour old (short after relaunching instance)

Every health check writes an log entry every view seconds into nodejs.log though.

I did not find any logs on the ec2 instance regarding log streaming.

1. Has anyone similar issues?
2. How do I make Elastic Beanstalk stream nodejs logs to CloudWatch logs.

--- EDIT

[ec2-user@ip-###-##-##-## log]$ cat /var/log/awslogs.log 
2017-03-07 11:01:05,928 - cwlogs.push.stream - INFO - 31861 - Thread-1 - Detected file rotation, notifying reader
2017-03-07 11:01:05,928 - cwlogs.push.stream - INFO - 31861 - Thread-1 - Reader is still alive.
2017-03-07 11:01:05,928 - cwlogs.push.stream - WARNING - 31861 - Thread-1 - No file is found with given path '/var/log/httpd/error.log*'.
2017-03-07 11:01:05,928 - cwlogs.push.stream - WARNING - 31861 - Thread-1 - No file is found with given path '/var/log/httpd/access.log*'.
2017-03-07 11:01:06,052 - cwlogs.push.reader - INFO - 31861 - Thread-8 - No data is left. Reader is leaving.
2017-03-07 11:01:10,929 - cwlogs.push.stream - INFO - 31861 - Thread-1 - Removing dead reader [2177a5cce5ed29525de329bfdc292ff1, /var/log/nginx/access.log]
2017-03-07 11:01:10,929 - cwlogs.push.stream - INFO - 31861 - Thread-1 - Starting reader for [92257964a10edeb586f084f4f2ba35de, /var/log/nginx/access.log]
2017-03-07 11:01:10,930 - cwlogs.push.reader - INFO - 31861 - Thread-11 - Start reading file from 0.
2017-03-07 11:01:10,930 - cwlogs.push.stream - WARNING - 31861 - Thread-1 - No file is found with given path '/var/log/httpd/error.log*'.
2017-03-07 11:01:10,930 - cwlogs.push.stream - WARNING - 31861 - Thread-1 - No file is found with given path '/var/log/httpd/access.log*'.
2017-03-07 11:01:15,931 - cwlogs.push.stream - WARNING - 31861 - Thread-1 - No file is found with given path '/var/log/httpd/error.log*'.
2017-03-07 11:01:15,931 - cwlogs.push.stream - WARNING - 31861 - Thread-1 - No file is found with given path '/var/log/httpd/access.log*'.
2017-03-07 11:01:16,788 - cwlogs.push.publisher - INFO - 31861 - Thread-7 - Log group: /aws/elasticbeanstalk/production/var/log/nginx/access.log, log stream: i-0bd24767864801e2c, queue size: 0, Publish batch: {'skipped_events_count': 0, 'first_event': {'timestamp': 1488884470930, 'start_position': 0L, 'end_position': 114L}, 'fallback_events_count': 0, 'last_event': {'timestamp': 1488884472931, 'start_position': 341L, 'end_position': 454L}, 'source_id': '92257964a10edeb586f084f4f2ba35de', 'num_of_events': 4, 'batch_size_in_bytes': 554}
2017-03-07 11:01:20,932 - cwlogs.push.stream - WARNING - 31861 - Thread-1 - No file is found with given path '/var/log/httpd/error.log*'.
2017-03-07 11:01:20,932 - cwlogs.push.stream - WARNING - 31861 - Thread-1 - No file is found with given path '/var/log/httpd/access.log*'.
2017-03-07 11:01:25,933 - cwlogs.push.stream - WARNING - 31861 - Thread-1 - No file is found with given path '/var/log/httpd/error.log*'.
2017-03-07 11:01:25,933 - cwlogs.push.stream - WARNING - 31861 - Thread-1 - No file is found with given path '/var/log/httpd/access.log*'.
2017-03-07 11:01:27,881 - cwlogs.push.publisher - INFO - 31861 - Thread-7 - Log group: /aws/elasticbeanstalk/production/var/log/nginx/access.log, log stream: i-0bd24767864801e2c, queue size: 0, Publish batch: {'skipped_events_count': 0, 'first_event': {'timestamp': 1488884481933, 'start_position': 454L, 'end_position': 568L}, 'fallback_events_count': 0, 'last_event': {'timestamp': 1488884482934, 'start_position': 568L, 'end_position': 681L}, 'source_id': '92257964a10edeb586f084f4f2ba35de', 'num_of_events': 2, 'batch_size_in_bytes': 277}

Answer 1

When Andrew (@andrew-ferk) and myself activated log streaming, it created all the log groups and streams in CloudWatch with the current log. After we deployed again, we noticed the logs stopped. This is because aws hashes the first line of the log. If it has seen that hash before it will treat that file like it's already been processed

If you are using npm start the first lines will be your application's name with version.

You can add a CMD date && npm start to your dockerfile to trigger a different first line each time or run npm in silent mode (as long as your first output is unique).

Also according to their docs you should add some policy to your elastic-beanstalk before enabling the feature AWS-Docs

{
  "Version": "2012-10-17",
  "Statement": [
    {
      "Effect": "Allow",
      "Action": [
        "logs:CreateLogGroup",
        "logs:CreateLogStream",
        "logs:GetLogEvents",
        "logs:PutLogEvents",
        "logs:DescribeLogGroups",
        "logs:DescribeLogStreams",
        "logs:PutRetentionPolicy"
      ],
      "Resource": [
        "*"
      ]
    }
  ]
}