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
Related
We are making use of AWS Lambda and have configured cloudwatch for logging. There is a cron job running every 5 minutes which is triggering the lambda function. The logs that are generated for the hit are getting created in different log streams. For reference, please check the image attached here:
So, let's say there is an API hit at 11:45, then for checking the logs I have to go through the log streams having last event time 2022-05-05 11:43:10 (UTC+05:30) , 2022-05-05 11:43:00 (UTC+05:30), 2022-05-05 11:38:11 (UTC+05:30) and 2022-05-05 11:38:02 (UTC+05:30) and so on. The reason is, for a single hit logs are getting created in different log streams. Some of the logs are in first log stream, some are in second, a few are in third one. Previously, all the logs were created in single log stream corresponding to a single hit. Is there anything that can be done to avoid this? as this makes debugging a time taking process.
This is how Lambda works: each Lambda execution environment gets its own log stream. If you need to look at logs across log streams, then the best "built-in" solution is CloudWatch Logs Insights, which works at the log-group level.
Update: this document describes the Lambda execution environment, and the conditions that cause creation/destruction of an environment.
I have an on-premise app deployed in an Application Server (e.g. Tomcat) and it generates its own log file. If I decide to migrate this to an AWS EC2, including the Application Server, is it possible to port my application logs in Cloudwatch instead? or is Cloudwatch only capable of logging the runtime logs in my application server? is it a lot of work to do this or is this even possible?
Kind of confuse on Cloudwatch. Seems it can do multiple things but is it really right to make it do that? Its only supposed to log metrics right, so it can alert whatever or whoever needs to be alerted.
If you have already developed application that produces its own log files, you can use CloudWatch Logs Agent to ingest the logs into CloudWatch Logs:
After installation is complete, logs automatically flow from the instance to the log stream you create while installing the agent. The agent confirms that it has started and it stays running until you disable it.
The metrics, such as RAM usage, disk space, can also be monitored and pushed to CloudWatch through the agent.
In both cases, logs and metrics, you can setup CloudWatch Alarms to automatically detect anomalies and notify you, or perform other actions, when they are detected. For logs, this is done through metric filters:
You can search and filter the log data coming into CloudWatch Logs by creating one or more metric filters. Metric filters define the terms and patterns to look for in log data as it is sent to CloudWatch Logs. CloudWatch Logs uses these metric filters to turn log data into numerical CloudWatch metrics that you can graph or set an alarm on.
update
You can also have your application to inject logs directly to CloudWatch logs using AWS SDK. For example, in python, you can use put_log_events.
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 have some AWS EC2 instances logging to CloudWatch Log Groups. When I open a Log Group, I can see my log streams listed:
However, when I click on one of the streams, I get an error:
Log stream not found The log stream version_0.2.41 date_2018-06-25
instance_i-02962ec6fbfd20c4c could not be found. Check if it was
correctly created and retry.
All this used to work before (it broke down somewhere in the last two weeks) and nothing has been modified on our part.
Any idea what's wrong here?
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.