Packaging AWS Lambda function with dependencies

This section explains how to deploy a lambda function with library dependencies (on Node JS). Most of the parts will be similar to previous section. The change will be in the way the source is bundled. We will notice how terraform modules can be reused here.

Samples for this tutorial are available in samples/06 folder.

(1) Install accounting.js dependency

Following example will use a node.js library accounting.js to format a number into currency. formatCurrencyLambda.js contains the lambda source.

From the samples/06 folder execute the following command to install accounting.js

npm install accounting

(2) Compress lambda source with dependencies

Here, we will bundle the source file with its node_module dependencies. The compressed formatCurrencyLambda.zip is the artifact will be deployed using Terraform.

Note: node_modules folder is included in the compressed formatCurrencyLambda.zip.

zip -r /tmp/formatCurrencyLambda.zip node_modules formatCurrencyLambda.js

(3) Terraform script for formatCurrencyLambda

Terraform script for deploying formatCurrencyLambda in AWS is in main.tf. This script (below) reuses the modules lambda and lambda-role.

• Only the locals values are changed to reflect the lambda name and zip file name. Otherwise, this script is very similar to the helloWorldLambda's main.tf
• Only the module reference has changed in output.tf. Otherwise, vars.tf and output.tf haven't changed as well.

provider "aws" {
  region = var.aws_region
}

module "lambda_tf_way_role" {
  source = "../modules/lambda-role"
}

locals {
  lambda_name = "formatCurrencyLambda"
  zip_file_name = "/tmp/formatCurrencyLambda.zip"
  handler_name = "formatCurrencyLambda.handler"
}

module "format_currency_lambda" {
  source = "../modules/lambda"
  lambda_function_name = local.lambda_name
  lambda_function_handler = local.handler_name
  lambda_role_arn = module.lambda_tf_way_role.lambda_role_arn
  lambda_zip_filename = local.zip_file_name
}

(4) Terraform Apply

Now we will run terraform script to create the Format Currency Lambda (with its IAM Role). You need to be in the samples/06 folder to run the script.

Note: The AWS_PROFILE is configured as lambda-tf-user

export AWS_PROFILE=lambda-tf-user
terraform init
terraform apply --auto-approve

(5) Invoke the lambda to test the dependency

We will invoke the formatCurrencyLambda via AWS CLI to test the deployment.

Note: If you are on AWS CLI v2, you have include the param --cli-binary-format raw-in-base64-out.

aws lambda invoke --function-name formatCurrencyLambda \
    --log-type Tail \
    --cli-binary-format raw-in-base64-out \
    --payload '{"value": 123456789}' \
    --profile "$AWS_PROFILE" \
    outputfile.txt

Print the contents outputfile.txt to see the formatted value of 123456789 as $123,456,789.00.

cat outputfile.txt

> Output :
{"amount":"\$123,456,789.00"}%

(6) Teardown

Now, we will delete the formatCurrencyLambda using terraform destroy, similar to helloWorldLambda. From the samples/06/ folder run the following command.

export AWS_PROFILE=lambda-tf-user
terraform destroy --auto-approve

Note: Once destroy completes, you should see a log similar to the one below.

module.lambda_tf_way_role.aws_iam_role_policy.lambda_tf_way_role_policy: Destroying... [id=tf_way_lambda_role:tf_way_lambda_role_policy]
module.format_currency_lambda.aws_lambda_function.lambda_tf_way_function: Destroying... [id=formatCurrencyLambda]
module.format_currency_lambda.aws_lambda_function.lambda_tf_way_function: Destruction complete after 0s
module.lambda_tf_way_role.aws_iam_role_policy.lambda_tf_way_role_policy: Destruction complete after 1s
module.lambda_tf_way_role.aws_iam_role.lambda_tf_way_role: Destroying... [id=tf_way_lambda_role]
module.lambda_tf_way_role.aws_iam_role.lambda_tf_way_role: Destruction complete after 3s

Destroy complete! Resources: 3 destroyed.

🏁 Congrats ! You deployed your 'first Lambda with dependencies' using Terraform and invoked it successfully. 🏁

Next: Lambda Layers