Allows an AWS Lambda function to be triggered by pre-configured CloudWatch event rules.
In contrast to the traditional schedule event that creates a new CloudWatch rule, the plugin assumes that an existing rule is already in place, and the Lambda function is specified as one of its targets. The plugin just adds necessary permissions to the Lambda function itself to complete the "link" between CloudWatch and Lambda.
Useful for projects that setup and scale infrastructure separately from code, e.g., deploy a Lambda function triggered by multiple timers or s3 events that are configured by scripts like Terraform, a separate CloudFormation template, or even a manually created infrastructure.
Also, can be useful for subscribing to an external (cross-account) rule.
plugins:- serverless-plugin-existing-cloudwatch-rulefunctions:key-rotation-lambda: #1handler: src/key-rotation-lambda.handlerevents:- cloudWatchRule: key-rotation-timercounter-lambda: #2handler: src/counter-lambda.handlerevents:- cloudWatchRuleArn: 'arn:aws:events:us-east-1:160879880353:rule/my-project-MidnightSchedule-42UGHOTBBVIET'scalable-lambda: #3handler: src/scalable-lambda.handlerevents:- cloudWatchRule: ANY
In the example,
key-rotation-timeris assumed to be setup and pointing to
key-rotation-lambda. The function
key-rotation-lambdawill be deployed on
serverless deployand, due to the plugin, with the necessary permissions to be invoked by
key-rotation-timer. The timer will be shown on the AWS Lambda -> Triggers page as if it was setup manually or using the traditional
scheduleevent. The prefix
rule/for the name is supported but optional for the plugin.
To attach a rule defined by its full ARN, use the
cloudWatchRuleArnproperty, such as in the
ANYkeyword allow for any trigger under the current AWS account, so
serverlessdoes not need to run on every change to the project's infrastructure. In the example, a new timer can be added that triggers
scalable-lambdawith a different set of arguments, but developers do not need to run
serverless deployor use CLI to change the permissions on the function.