Add samples for using hot reloading with terraform, fix role arns (#210)

Co-authored-by: Dominik Schubert <[email protected]>

Author: dfangl

cloudwatch-metrics-aws/run.sh

@@ -14,7 +14,7 @@ awslocal lambda create-function \
     --zip-file fileb://failing-lambda.zip \
     --handler failing-lambda.lambda_handler \
     --runtime python3.8 \
-    --role my-role
+    --role arn:aws:iam::000000000000:role/my-role
 
 echo 'creating sns topic'
 topic_arn=$(awslocal sns create-topic --name my-topic-alarm | jq -r .TopicArn)

lambda-function-urls/javascript/Makefile

@@ -16,7 +16,7 @@ run:         ## Build, deploy, and invoke the Lambda function URL
 		--runtime nodejs14.x \
 		--zip-file fileb://function.zip \
 		--handler index.handler \
-		--role cool-stacklifter
+		--role arn:aws:iam::000000000000:role/cool-stacklifter
 
 	awslocal lambda create-function-url-config \
 		--function-name localstack-lamba-url-example \

lambda-function-urls/javascript/README.md

@@ -25,7 +25,7 @@ awslocal lambda create-function \
     --runtime nodejs14.x \
     --zip-file fileb://function.zip \
     --handler index.handler \
-    --role cool-stacklifter
+    --role arn:aws:iam::000000000000:role/cool-stacklifter
 ```
 
 ## Creating a Lambda function URL

lambda-function-urls/python/Makefile

@@ -18,7 +18,7 @@ run:         ## Build, deploy, and invoke the Lambda function URL
 		--timeout 10 \
 		--zip-file fileb://function.zip \
 		--handler lambda_function.lambda_handler \
-		--role cool-stacklifter
+		--role arn:aws:iam::000000000000:role/cool-stacklifter
 
 	awslocal lambda create-function-url-config \
 		--function-name trending \

lambda-hot-reloading/javascript-terraform-layers/.gitignore

@@ -0,0 +1 @@
+!layer_src/**

lambda-hot-reloading/javascript-terraform-layers/README.md

@@ -0,0 +1,115 @@
+# LocalStack Demo: Hot code swapping for Lambda functions using LocalStack’s code mounting in JavaScript
+
+## Prerequisites
+
+* LocalStack Pro
+* Docker
+* [awslocal](https://github.com/localstack/awscli-local) CLI
+* Terraform
+* [tflocal](https://github.com/localstack/terraform-local) CLI
+
+## Introduction to the sample
+In this sample, we demonstrate a hot reloading setup where both the function code and the layer code are hot reloaded.
+Any changes to either of those two directories will reload the function. The changed code will be available almost immediately for the next invocation.
+
+We will again re-use the sample from our [javascript](../javascript/) sample, but one of the values we want to change is supplied by a function defined in our layer.
+
+We will use terraform to deploy a hot reloaded lambda function and invoke it once. Afterwards we will change its source and invoke it again to demonstrate the hot-reload feature.
+
+The source code of the created lambda function `hotreloadlambda` is located in the subfolder [lambda_src](./lambda_src/) and the source code of the created layer `hot_reload_layer` is located in the subfolder [layer_src](./layer_src/).
+
+
+## Starting up
+
+First, we need to make sure we start LocalStack with the right configuration. 
+Hot reloading of layers is only supported in our new lambda provider, all you need to do is set `PROVIDER_OVERRIDE_LAMBDA=v2`, if you use a LocalStack version < 2.0.
+
+```bash
+PROVIDER_OVERRIDE_LAMBDA=v2 localstack start
+```
+
+Accordingly, if you are launching LocalStack via Docker or Docker Compose:
+
+```bash
+#docker-compose.yml
+
+services:
+  localstack:
+    ...
+    environment:
+      ...
+      - PROVIDER_OVERRIDE_LAMBDA=v2
+```
+
+## Deploying
+
+Now we can deploy our terraform stack by using `tflocal`.
+First, we initialize the terraform working directory using:
+
+```bash
+tflocal init
+```
+
+Afterwards, we can deploy our stack on LocalStack:
+
+```bash
+tflocal apply
+```
+
+The terraform configuration will automatically deploy the lambda with hot reloading for the function code.
+The function code consists of the contents of the `lambda_src` subdirectory and the layer code in the `layer_src` subdirectory.
+
+## Invoking the Lambda function
+
+We can quickly make sure that our deployed function works by invoking it with a simple payload:
+
+```bash
+awslocal lambda invoke --function-name hotreloadlambda output.txt
+```
+
+The invocation response:
+
+```json
+{
+    "Number1": 21,
+    "Number2": 31,
+    "Sum": 52,
+    "Product": 651,
+    "Difference": 10,
+    "Quotient": 0.6774193548387096
+}
+```
+
+## Changing things up
+
+Now, that we got everything up and running, the real fun begins. Because the function code directory, in our case `./lambda_src`, is mounted directly into the executing container, any changes that we make in this folder will be reflected in the execution almost instantly.
+
+To demonstrate this behavior, we can now make a minor change to the API and replace `number2` with a new value, let's say 20. Without redeploying or updating the function, the result of the previous request will look like this:
+
+```json
+{
+    "Number1": 21,
+    "Number2": 20,
+    "Sum": 41,
+    "Product": 420,
+    "Difference": 1,
+    "Quotient": 1.05
+}
+```
+
+We can now also change the value provided by our layer. Let's replace it with 10, by editing the index.js in our `./layer_src/nodejs/node_modules/test-dep` folder.
+
+Our output after another invoke will be:
+
+```json
+{
+    "Number1": 10,
+    "Number2": 20,
+    "Sum": 30,
+    "Product": 200,
+    "Difference": 10,
+    "Quotient": 0.5
+}
+```
+
+Now we can change layer and function independently or together, and test the outcome in real time.

lambda-hot-reloading/javascript-terraform-layers/lambda_src/index.js

@@ -0,0 +1,18 @@
+const testDep = require('test-dep')
+
+exports.handler = async function (event, context) {
+    var number1 = testDep();
+    var number2 = 31;
+    var sum = number1 + number2;
+    var product = number1 * number2;
+    var difference = Math.abs(number1 - number2);
+    var quotient = number1 / number2;
+    return {
+        "Number1": number1,
+        "Number2": number2,
+        "Sum": sum,
+        "Product": product,
+        "Difference": difference,
+        "Quotient": quotient
+    };
+ };

lambda-hot-reloading/javascript-terraform-layers/layer_src/nodejs/node_modules/test-dep/index.js

@@ -0,0 +1,71 @@
+terraform {
+  required_providers {
+    aws = {
+      source  = "hashicorp/aws"
+      version = "~> 4.0"
+    }
+  }
+}
+
+# Configure the AWS Provider
+provider "aws" {
+  region = "us-east-1"
+}
+
+resource "aws_iam_role" "iam_for_lambda" {
+  name = "iam_for_lambda"
+
+  assume_role_policy = <<EOF
+{
+  "Version": "2012-10-17",
+  "Statement": [
+    {
+      "Action": "sts:AssumeRole",
+      "Principal": {
+        "Service": "lambda.amazonaws.com"
+      },
+      "Effect": "Allow",
+      "Sid": ""
+    }
+  ]
+}
+EOF
+}
+
+resource "aws_lambda_layer_version" "test_layer" {
+  layer_name = "hot_reload_layer"
+  compatible_runtimes = ["nodejs16.x"]
+
+  s3_bucket = "hot-reload"
+  s3_key    = "${abspath(path.root)}/layer_src"
+
+}
+
+resource "aws_lambda_function" "test_lambda" {
+  # If the file is not in the current working directory you will need to include a
+  # path.module in the filename.
+  function_name = "hotreloadlambda"
+  role          = aws_iam_role.iam_for_lambda.arn
+  handler       = "index.handler"
+
+
+  s3_bucket = "hot-reload"
+  s3_key    = "${abspath(path.root)}/lambda_src"
+  layers = [aws_lambda_layer_version.test_layer.arn]
+
+  runtime = "nodejs16.x"
+
+  environment {
+    variables = {
+      foo = "bar"
+    }
+  }
+}
+
+output "hot_reloading_lambda_arn" {
+  value = aws_lambda_function.test_lambda.arn
+}
+
+output "hot_reloading_layer_arn" {
+  value = aws_lambda_layer_version.test_layer.arn
+}

lambda-hot-reloading/javascript-terraform-layers/main.tf

@@ -0,0 +1,105 @@
+# LocalStack Demo: Hot code swapping for Lambda functions using LocalStack’s code mounting in JavaScript
+
+## Prerequisites
+
+* LocalStack
+* Docker
+* [awslocal](https://github.com/localstack/awscli-local) CLI
+* Terraform
+* [tflocal](https://github.com/localstack/terraform-local) CLI
+
+## Introduction to the sample
+Other than the deployment of the sample, it is practically identical to [our javascript hot reloading sample](../javascript/).
+
+We will use terraform to deploy a hot reloaded lambda function, and then interact with it by invoking it and changing its source.
+
+The source code of the created lambda function `hotreloadlambda` is located in the subfolder [lambda_src](./lambda_src/).
+
+
+## Starting up
+
+First, we need to make sure we start LocalStack with the right configuration. 
+To use our new lambda provider, all you need to do is set `PROVIDER_OVERRIDE_LAMBDA=v2`, if you use a LocalStack version < 2.0.
+
+
+If you want to use our old provider, please set `LAMBDA_REMOTE_DOCKER` to `0` (see the [Configuration Documentation](https://docs.localstack.cloud/localstack/configuration/#lambda) for more information):
+
+```bash
+LAMBDA_REMOTE_DOCKER=0 localstack start
+```
+
+Accordingly, if you are launching LocalStack via Docker or Docker Compose:
+
+```bash
+#docker-compose.yml
+
+services:
+  localstack:
+    ...
+    environment:
+      ...
+      - LAMBDA_REMOTE_DOCKER=0
+```
+
+## Deploying
+
+Now we can deploy our terraform stack by using `tflocal`.
+First, we initialize the terraform working directory using:
+
+```bash
+tflocal init
+```
+
+We can now check the plan of terraform for our deployment:
+
+```bash
+tflocal plan
+```
+
+Afterwards, we can deploy our stack on LocalStack:
+
+```bash
+tflocal apply
+```
+
+The terraform configuration will automatically deploy the lambda with hot reloading for the function code.
+The function code will be the contents of the `lambda_src` subdirectory.
+
+## Invoking the Lambda function
+
+We can quickly make sure that it works by invoking it with a simple payload:
+
+```bash
+awslocal lambda invoke --function-name hotreloadlambda output.txt
+```
+
+The invocation itself returns:
+
+```json
+{
+	"Difference": 10,
+	"Number1": 21,
+	"Number2": 31,
+	"Product": 651,
+	"Quotient": 0.6774193548387096,
+	"Sum": 52
+}
+```
+
+## Changing things up
+
+Now, that we got everything up and running, the fun begins. Because the function code directory, in our case `./lambda_src` is mounted into the executing container, any change that we save in this folder will affect the execution almost instantly.
+
+For example, we can now make a minor change to the API and replace the `number1` and `number2` with new values, let's say 10 and 20. Without redeploying or updating the function, the result of the previous request will look like this:
+
+```json
+{
+	"Difference": 10,
+	"Number1": 10,
+	"Number2": 20,
+	"Product": 200,
+	"Quotient": 0.5,
+	"Sum": 30
+}
+```
+