Migrating Curl CronJobs to Lambda from K8s Deployments

A centralized and standardized setup for deploying Lambda-based cron jobs using Terraform modules, especially those utilizing a universal curl container image for simple HTTP-based tasks.

Universal curl image:

First, prepare a universal curl image that will be used to execute dynamically passed curl commands. In this example, Node.js is used to build the curl image.

Dockerfile

handler.js

package.json

Command to build & push amd64 universal curl image,

Lambda Terraform Module:

In the lambda/lambda.tf file, define the Lambda services and cron job schedule.

The Terraform configuration uses an S3 backend for state management. You should configure the backend by ensuring the backend.tf points to the appropriate backend configuration for your environment.

Additionally, ensure that the AWS provider is properly configured in providers_aws.tf, which is symlinked from common config.

Key Resources and Attributes:

File	Resource	Attributes & Description
`events.tf`	`aws_cloudwatch_event_rule`	Cron-based scheduling for Lambda
	`aws_cloudwatch_event_target`	Binds Lambda to EventBridge
	`aws_lambda_permission`	Grants EventBridge invoke rights
`iam.tf`	`aws_iam_role`, `aws_iam_policy`	Execution, VPC, and ECR policies
`lambda.tf`	`aws_lambda_function`	Core Lambda configuration
`sg.tf`	aws_security_group	SG allowing egress (0.0.0.0/0)
`variables.tf`		Inputs for customization

Module Structure:

events.tf

iam.tf

lambda.tf

sg.tf

variables.tf

Common Config

providers_aws.tf

versions.tf

pipeline_config

Lambda deployment:

In the lambda.tf file, define the Lambda services and cron job schedule.

.terraenv

backend.tf

data.tf

lambda.tf

variables.tf

Same approach can be applied in staging (stgfolder).

Verify the Deployment:

Once the deployment completes, verify the following resources:

Lambda Functions: Go to the Lambda Console to check that the Lambda functions are deployed and configured correctly.
EventBridge Rules: Verify that the EventBridge cron jobs are created in the EventBridge Console.
CloudWatch Logs: Check the logs for Lambda functions in CloudWatch Logs.

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