How to use the command awslogs (with examples)
The awslogs command is a useful tool that allows users to query groups, streams, and events from Amazon CloudWatch logs. It provides a convenient way to interact with logs stored in CloudWatch and retrieve the necessary information.
Use case 1: List log groups
Code:
awslogs groups
Motivation:
This use case is helpful when you want to obtain a list of all the log groups available in CloudWatch. By running this command, you can quickly see the log groups and understand the structure and organization of your logs.
Explanation:
The groups parameter is used with the awslogs command to retrieve a list of all the log groups in CloudWatch. When executing this command, it will return the log group names and other relevant information.
Example output:
Log Group
-----------------------------------------
/var/log/aws/rds/instances
/var/log/aws/lambda/my_lambda_group
/var/log/aws/ecs/containers
/var/log/aws/ecs/ecs-agent
/var/log/aws/ecs/tasks
Use case 2: List existing streams for the specified group
Code:
awslogs streams /var/log/syslog
Motivation:
When working with log streams, it is important to have visibility into the available streams for a particular log group. This use case allows you to retrieve a list of existing streams for the specified log group, aiding in troubleshooting or analyzing specific logs.
Explanation:
The streams parameter is used to list the existing log streams for the provided log group name. By passing the desired log group as a parameter, you can gather information about all the streams associated with that group.
Example output:
Log Stream
-----------------------------------------
i-0123456789abcdefg
i-0123456789abcdefh
i-0123456789abcdefi
Use case 3: Get logs for any streams in the specified group between 1 and 2 hours ago
Code:
awslogs get /var/log/syslog --start='2h ago' --end='1h ago'
Motivation:
This use case is useful when you need to retrieve logs from a specific time range in the past. By specifying the desired log group and the start and end time, you can easily obtain the logs within the specified timeframe.
Explanation:
The get parameter is used to fetch logs from the provided log group. The --start and --end arguments define the time range for which logs will be retrieved. In this example, logs from 2 hours ago to 1 hour ago are fetched.
Example output:
2022-01-01 10:00:00 [INFO] This is a log message
2022-01-01 10:01:00 [ERROR] An error occurred
2022-01-01 10:02:00 [INFO] Another log message
Use case 4: Get logs that match a specific CloudWatch Logs Filter pattern
Code:
awslogs get /aws/lambda/my_lambda_group --filter-pattern='ERROR'
Motivation:
When dealing with a large number of logs, it can be challenging to locate specific log entries. This use case enables you to retrieve logs that match a specific pattern, making it easier to identify and analyze relevant log messages.
Explanation:
The get parameter is used to retrieve logs from the provided log group. The --filter-pattern argument is used to specify a CloudWatch Logs Filter pattern. In this example, only logs containing the word “ERROR” will be retrieved.
Example output:
2022-01-01 10:01:00 [ERROR] An error occurred
2022-01-01 10:03:00 [ERROR] Another error happened
Use case 5: Watch logs for any streams in the specified group
Code:
awslogs get /var/log/syslog ALL --watch
Motivation:
In some situations, you may need to continuously monitor logs as they are being generated. This use case helps you watch logs in real-time, ensuring that you can quickly respond to any critical events or errors.
Explanation:
The get parameter, along with the --watch option, is used to continuously fetch and display logs as they are generated. By including the keyword “ALL” after the log group name, you can retrieve logs from all available streams within the specified group.
Example output:
2022-01-01 10:00:00 [INFO] This is a log message
2022-01-01 10:01:00 [ERROR] An error occurred
2022-01-01 10:02:00 [INFO] Another log message
2022-01-01 10:03:00 [ERROR] Another error happened
...
Conclusion:
The awslogs command is a versatile tool for interacting with Amazon CloudWatch logs. It provides a range of capabilities, from listing log groups and streams to fetching logs based on time ranges or specific patterns. Understanding and utilizing these use cases can greatly improve log analysis and troubleshooting processes.
