AWS CloudWatch has Log Groups and Log streams. A log group seems reasonable to me: Each product (e.g. each Lambda function, each Sagemaker endpoint) has its own log group.
But then there are log streams. When does AWS CloudWatch create new log streams? Can I search all log streams of a log group?
From the AWS Cloudwatch documentation you can see that a log stream is created each time the logs come from a different event source. In case of Lambda, it's one stream per Lambda container where each container might process multiple events.
A log stream is a sequence of log events that share the same source. Each separate source of logs into CloudWatch Logs makes up a separate log stream.
Yes, you can search all log streams of a log group using the CloudWatch Logs API. The FilterLogEvents action allows you to search through a log group.
Related
I am using Elasitsearch to get logs from cloudwatch log group by subscribing a lambda to the log group. So whenever there is a log event pushed to the log group, my lambda will be triggered and it will save the log to Elasticsearch. Then I can search the log via Kibana dashboard.
I'd like to put the metrics data to Elasticsearch as well but I couldn't find a way to subscribe to metrics data.
You can use AWS Module in MetricBeat from the Elastic Beat's family. Note that pulling metrics from cloudwatch will result in chargeable API calls. So you should carefully consider the scraping frequency.
Thanks
I want to send logs data from my EC2 instance (Ubuntu) to an AWS eventbridge where I can then send them to multiple endpoints. e.g. if someone performs a root user operation on the server this is written to/var/log/auth.log, I would then like this change in the log to be sent to eventbridge where it can then be routed to other locations, how can achieve this?
cheers
N.B.
I have tried using the cloudwatch agent but I can't figure how to get the logs to eventbridge once they're in a log group, so if there is a way I can this that would also work.
I can't figure how to get the logs to eventbridge once they're in a log group, so if there is a way I can this that would also work.
Once your CloudWatch Agent writes relevant logs to CloudWatch logs, you can setup a subscription filter on your log group.
The filter would stream logs of interest (e.g. those that contain ssh) into a lambda function. How to set it up is shown in:
Example 2: Subscription Filters with AWS Lambda
The lambda, using events api, e.g. in boto3, could process the log stream, filter out messages, construct events and publish them to the event bridge.
I want to create CloudWatch Rule that would be triggered upon creation of Log Event. For that reason as an event pattern I selected CloudWatch Logs service but when I try to generate some Cloud Watch logs the rule is not getting triggered. I can not find any example of using aws.logs as a source for an event and hence my question if I'm doing something wrong.
This is because the only events for logs available are AWS API Call via CloudTrail. CloudWatch Logs does not generate CloudWatch events on receiving new log entries.
For the Logs API call events to work, you need to setup CloudTrial trial.
However, if you want to trigger your lambda function based on log entries, I can recommend using subscription filters for lambda:
You can use subscriptions to get access to a real-time feed of log events from CloudWatch Logs and have it delivered to other services such as a Amazon Kinesis stream, Amazon Kinesis Data Firehose stream, or AWS Lambda for custom processing, analysis, or loading to other systems.
I have recently started learning about AWS cloud watch and I want to understand the concept of creating Logs so I went through a lot of links like
https://aws.amazon.com/answers/logging/centralized-logging/
I could understand that we can create log groups but and logs are basically to track activity. Is there anything more to it. When do the logs get created.
Any help would be highly appreciated!
You can get more details about Log Groups and CloudWatch Logs Concepts here
Following is the extract from that page
Log Events
A log event is a record of some activity recorded by the application or resource being monitored. The log event record that
CloudWatch Logs understands contains two properties: the timestamp of
when the event occurred, and the raw event message. Event messages
must be UTF-8 encoded.
Log Streams
A log stream is a sequence of log events that share the same source. More specifically, a log stream is generally intended to
represent the sequence of events coming from the application instance
or resource being monitored. For example, a log stream may be
associated with an Apache access log on a specific host. When you no
longer need a log stream, you can delete it using the aws logs
delete-log-stream command. In addition, AWS may delete empty log
streams that are over 2 months old.
Log Groups
Log groups define groups of log streams that share the same retention, monitoring, and access control settings. Each log stream
has to belong to one log group. For example, if you have a separate
log stream for the Apache access logs from each host, you could group
those log streams into a single log group called
MyWebsite.com/Apache/access_log.
And to answer your question "When do the logs get created.", basically that is completely dependent on your application. However, whenever they are created they get streamed to cloudwatch streams (if you have installed the cloudwatch agent and are streaming that particular log)
The advantage of using cloudwatch is that you can retain logs even after your EC2 instance is terminated and you dont need to SSH into the resource to check the logs, you can simply get that from AWS Console
The AWS documentation indicates that multiple log event records are provided to Lambda when streaming logs from CloudWatch.
logEvents
The actual log data, represented as an array of log event
records. The "id" property is a unique identifier for every log event.
How does CloudWatch group these logs?
Time? Count? Randomly, from my perspective?
Currently you get one Lambda invocation for every PutLogEvents batch that CloudWatch Logs had received against that log group. However you should probably not rely on that because AWS could always change it (for example batch more, etc).
You can observe this behavior by running the CWL -> Lambda example in the AWS docs.
Some aws services allow you to configure the log intervals such as elastic load balancing. There's a choice between five and sixty minute log intervals. You may not see a specific increment or parameter in the docs because they are configurable based on each service.