AWS SDK for Go Code Examples for Amazon CloudWatch

Purpose

These examples demonstrate how to perform the following tasks in your default AWS Region using your default credentials:

• Get a list of alarms (DescribeAlarms)
• Create and enable an alarm (EnableAlarm)
• Disable an alarm (DisableAlarm)
• Delete an alarm (DeleteAlarm)
• List resource metrics (ListMetrics)
• Create a custom metric (CreateCustomMetric)
• Create an event (CreateRole, CreateRule, Lambda, UploadLambdaFunction, CreateTarget, SendEvent)
• Display events (GetLogEvents)

Prerequisites

You must have an AWS account, and have your default credentials and AWS Region configured as described in Configuring the AWS SDK for Go in the AWS SDK for Go Developer Guide.

Running the Code

Each operation is in a sub-folder. Some operations depend upon results from another operation. For example, to create a target, you need the ARN of the Lambda function that is invoked.

Most unit tests for the operations require that you fill in some values in *config.json".

CreateCustomMetric

This operation creates a new metric in a namespace.

go run CreateCustomMetric.go -n NAMESPACE -m METRIC-NAME -u UNITS [-v VALUE] -dn DIMENSION-NAME -dv DIMENSION-VALUE

where:

• NAMESPACE is the namespace.
• METRIC-NAME is the name of the metric.
• UNITS are the units for the metric.
• VALUE is the value of the units. The default value is 0.0.
• DIMENSION-NAME is the name of the dimension.
• DIMENSION-VALUE is the value of the dimension.

You must supply similar values in config.json for the unit test.

The unit test:

1. Creates a custom metric for each metric in config.json.
2. Lists the custom metrics.

CreateRole

This operation creates an IAM role that grants permission to CloudWatch Events as step one of the workflow of creating an event.

go run CreateRole -p POLICY -r ROLE

where:

• POLICY is the name of the policy.
• ROLE is the name of the role.

You must supply similar values in config.json for the unit test.

The unit test:

1. Creates a Role with a random name if one is not supplied in config.json.
2. Deletes the Role if it created it.

CreateRule

This operation creates a rule that watches for events on a schedule as step two of the workflow of creating an event.

go run CreateRule -r RULE -a ROLE-ARN -s SCHEDULE`

where:

• RULE is the name of the rule.
• ROLE-ARN is the ARN of the role.
• SCHEDULE is the schedule expression, such as rate(5 minutes) to have the rule run every five minutes.

You must supply similar values in config.json for the unit test.

The unit test:

1. Creates a Rule using a random name if the name isn't supplied in config.json
2. Deletes the Rule if it created it

CreateTarget

This operation creates an event target that is the resource that is invoked when the rule is triggered as step five of the workflow of creating an event.

go run CreateTarget.go -r RULE -l LAMBDA-ARN -t TARGET

where:

• RULE is the of the rule.
• LAMBDA-ARN is the ARN of the Lambda function that is invoked.
• TARGET is th ID of the target.

You must supply a Lambda ARN value in config.json for the unit test.

The unit test:

1. Creates a new target with a random name if a name is not supplied in config.json.
2. Deletes the target if it created it.

DeleteAlarm

This operation deletes an alarm.

go run DeleteAlarm.go -a ALARM

where:

• ALARM is the name of the alarm.

You can supply a similar value in config.json for the unit test.

The unit test:

1. Creates an alarm with a random name if the name is not supplied in config.json.
2. Deletes the alarm if it created the alarm.

DescribeAlarms

This operation lists your Amazon CloudWatch alarms.

go run DescribeAlarms.go

DisableAlarm

This operation disables an alarm.

go run DisableAlarm -a ALARM

where:

• ALARM is the name of the alarm.

You can supply a similar value in config.json for the unit test.

The unit test:

1. Creates and enables an alarm with a random name if the name is not supplied in config.json.
2. Disables and deletes the alarm if it created the alarm.

EnableAlarm

This operation creates and enables an alarm when the CPU utilization of an Amazon EC2 instance goes above 70%, triggering a reboot of the instance.

go run EnableAlarm -n INSTANCE-NAME -i INSTANCE-ID -a ALARM-NAME

where:

• INSTANCE-NAME is the name of your Amazon EC2 instance.
• INSTANCE-ID is the ID of your Amazon EC2 instance.
• ALARM-NAME is the name of the alarm.

You must supply similar values in config.json for the unit test.

The unit test:

1. Creates an alarm with a random name if the name is not supplied in congig.json.
2. Enables the alarm.
3. Deletes the alarm if it created the alarm.

GetLogEvents

This operation lists the log events for a log stream in a log group.

go run GetLogEvents.go -l LOG-GROUP -s LOG-STREAM [-l LIMIT]

where:

• LOG-GROUP is the name of the log group.
• LOG-STREAM is the name of the log stream.
• LIMIT is the maximum number of events to display. If omitted, defaults to 100.

You can supply similar values in config.json for the unit test.

The unit test:

1. Restricts the limit value to the range of 1 to 100.
2. Gets a log stream from the user's log groups if either name is not supplied in config.json.
3. Lists the events for the log stream in the log group.

Lambda

The main.go file in this folder logs any CloudWatch event it receives. Use the packageLambda.bat file for Windows or the packageLambda.sh file to create main.zip from main.go. Creating the ZIP file is step three of the workflow of creating an event. Note that you still must upload the Lambda function to a bucket before you can use it as a target. See UploadLambdaFunction.

packageLambda.bat OR packageLambda.sh

ListMetrics

This operation lists up to 500 of your metrics.

go run ListMetrics.go

SendEvent

This operation sends an event as the final step of the workflow of creating an event. It sends the event that is defined in event.json.

go run SendEvent.go -l LAMBDA-ARN

where:

• LAMBDA-ARN is the ARN of the Lambda function to which the event is sent.

You must supply a similar value in config.json for the unit test.

The unit test:

1. Creates an event.

UploadLambdaFunction

This operation uploads a Lambda function to an Amazon S3 bucket as step four of the workflow of creating an event.

go run UploadLambdaFunction.go -z ZIP-FILE -b BUCKET -f LAMBDA-FUNCTION [-h HANDLER] -a ROLE-ARN [-r RUNTIME]

where:

• ZIP-FILE is the name of the ZIP file, without the .zip extension.
• BUCKET is the name of the Amazon S3 bucket.
• LAMBDA-FUNCTION is the name of the Lambda function.
• HANDLER is the name of the package class containing the function. The default is main.
• ROLE-ARN is the ARN of the role that enables calling the function
• RUNTIME is the runtime for the function. The default is go1.x.

You can supply similar values in config.json for the unit test. If you do not, the unit test creates and deletes these resources.

The unit test:

1. Sets the runtime to go1.x if not set.
2. Creates a new role if the role ARN is not set.
3. Sets the handler to main if it is not set.
4. Creates a new bucket if it is not set.
5. Creates a new Lambda function if it is not set.
6. Sets the zip name to main if it is not set.
7. Calls CreateFunction to upload the ZIP file to the bucket and create the function.
8. If it created a new Lambda function, it deletes it.
9. If it created a new bucket, it deletes it.
10. If it created a new role, it deletes it.

Notes

• We recommend that you grant this code least privilege, or at most the minimum permissions required to perform the task. For more information, see Grant Least Privilege in the AWS Identity and Access Management User Guide.
• This code has not been tested in all Regions. Some AWS services are available only in specific Regions.
• Running this code might result in charges to your AWS account.

Running the Unit Tests

Unit tests should delete any resources they create. However, they might result in charges to your AWS account.

To run the unit tests, navigate to a sub-folder and enter:

go test

You should see something like the following, where PATH is the path to folder containing the Go files:

PASS
ok      PATH 6.593s

If you want to see any log messages, enter:

go test -test.v

You should see some additional log messages. The last two lines should be similar to the previous output shown.