11 Create an AWS Lambda.md

Create an AWS Lambda

To ensure none of this is getting Azure-specific, I'll add and deploy AWS Lambda with all the same functionality and tests.

After signing up for an AWS account, install the AWS CLI - e.g. using Chocolatey from an Administrator PowerShell prompt

choco install awscli

And install the dotnet templates for AWS projects (from your non-elevated prompt)

dotnet new -i Amazon.Lambda.Templates

Then create a new project with the .net 5 runtime, in a temporary folder (so the projects can be moved about to match the folder structure in the repo)

mkdir AwsTemp
cd AwsTemp
dotnet new lambda.CustomRuntimeFunction --name WordValues.Aws --language F#
move WordValues.Aws\src\WordValues.Aws ..
move WordValues.Aws\test\WordValues.Aws.Tests ..

Tweaking the projects

In the WordValues.Aws.fsproj file

-  <ItemGroup>
-     <PackageReference Include="Amazon.Lambda.Core"  Version="1.2.0" />
-     <PackageReference Include="Amazon.Lambda.- RuntimeSupport" Version="1.3.0" />
-     <PackageReference Include="Amazon.Lambda.- Serialization.SystemTextJson" Version="2.1.0" />
-  </ItemGroup>

And then add the packages with paket

dotnet paket add FSharp.Core --project WordValues.Aws
dotnet paket add Amazon.Lambda.Core --project WordValues.Aws
dotnet paket add Amazon.Lambda.RuntimeSupport --project WordValues.Aws
dotnet paket add Amazon.Lambda.Serialization.SystemTextJson --project WordValues.Aws

For WordValues.Aws.Tests.fsproj

-  <ItemGroup>
-    <PackageReference Include="Amazon.Lambda.Core" Version="1.2.0" />
-    <PackageReference Include="Amazon.Lambda.TestUtilities" Version="1.2.0" />
-    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="15.5.0" />
-    <PackageReference Include="xunit" Version="2.3.1" />
-    <PackageReference Include="xunit.runner.visualstudio" Version="2.3.1" />
-    <DotNetCliToolReference Include="dotnet-xunit" Version="2.3.1" />
-  </ItemGroup>
  <ItemGroup>
-    <ProjectReference Include="..\..\src\WordValues.Aws\WordValues.Aws.fsproj" />
+    <ProjectReference Include="..\WordValues.Aws\WordValues.Aws.fsproj" />
  </ItemGroup>

And fix up the package references

dotnet paket add FSharp.Core --project WordValues.Aws.Tests
dotnet paket add Microsoft.NET.Test.Sdk --project WordValues.Aws.Tests
dotnet paket add Amazon.Lambda.Core --project WordValues.Aws.Tests
dotnet paket add Amazon.Lambda.TestUtilities --project WordValues.Aws.Tests
dotnet paket add Microsoft.NET.Test.Sdk --project WordValues.Aws.Tests
dotnet paket add xunit --project WordValues.Aws.Tests
dotnet paket add xunit.runner.visualstudio --project WordValues.Aws.Tests
dotnet paket add coverlet.collector --project WordValues.Aws.Tests

Now the project should build and its tests should pass.

Making the AWS Lambda do the same thing the Azure Function does

We need to change the return type of the lambda to a APIGatewayProxyResponse, which requires another package.

dotnet paket add Amazon.Lambda.APIGatewayEvents --project WordValues.Aws

Then make the Aws Lambda function similar to the Azure Function version.

-    let functionHandler (input: string) (context: ILambdaContext) =
+    let functionHandler (word : string) (context: ILambdaContext) =

-        match input with
-        | null -> String.Empty
-        | _ -> input.ToUpper()
+        if not (isNull word) then
+            let result = Calculate.wordValue word
+            let content = JsonSerializer.Serialize<_>(result, JsonSerializerOptions(IgnoreNullValues = true))
+
+            APIGatewayProxyResponse(
+                StatusCode = int HttpStatusCode.OK,
+                Body       = content,
+                Headers    = dict [ ("Content-Type", "application/json") ]
+                )
+        else
+            APIGatewayProxyResponse(
+                StatusCode = int HttpStatusCode.BadRequest,
+                Body       = "Required query parameter 'word' was missing",
+                Headers    = dict [ ("Content-Type", "text/plain;charset=utf-8") ]
+                )

And finally, the tests should be replaced with 'ports' of the Azure Function tests.