Invoke a lambda function when another lambda function is deployed - amazon-web-services

Question

I have an AWS lambda function that provides configuration objects. Whenever this lambda function is updated(i.e deployed again), I need to trigger another lambda function, that detects changes in those config objects and takes some action. How do I monitor this lambda deployment, which cloud watch event do I need to subscribe to?

Answer 1

I assume that your lambda deployments are not managed by CodeDeploy. If so, I would recommend looking into creating a CloudTrial trial.
Once CT trial is created with default settings, it will monitor all management API calls to your lambda function. One of them is UpdateFunctionCode. Thus you can create a CloudWatch rule for AWS API Call via CloudTrail. The rule would be triggered on the function update API call.
Example of such a rule:
{
"source": [
"aws.lambda"
],
"detail-type": [
"AWS API Call via CloudTrail"
],
"detail": {
"eventSource": [
"lambda.amazonaws.com"
],
"eventName": [
"UpdateFunctionCode"
]
}
}
Then you can trigger a second lambda, based on the captured update event of the first function.

Answer 2

Based on #Marcin's suggestion, used console log to print the event. The below rule helped to filter a specific function;
{
"source": [
"aws.lambda"
],
"detail-type": [
"AWS API Call via CloudTrail"
],
"detail": {
"eventSource": [
"lambda.amazonaws.com"
],
"eventName": [
"UpdateFunctionCode20150331v2"
],
"responseElements": {
"functionName": [
"myFunction"
]
}
}
}