C# on AWS Lambda
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@phermens

About me
Pat Hermens
● Father of two
● Based in Rotterdam
● Lead Developer at Coolblue
● Still have a soft-spot for VB6
https://hermens.com.au/
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Every day a little more Dutch
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A little bit of history
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Launched in Nov 2014.
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C# support in Dec 2016.
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Officially only supports .NET Core.
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AWS was first of the “major providers”.
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They have an open-source SDK
https://github.com/aws/aws-sdk-net/ 9
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They also have a great ‘dotnet’ repo…
https://github.com/aws/aws-lambda-dotnet/ 10
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… & most of my tooling is from here
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It’s “Hello world” time!
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Hello World! (including ILambdaContext)

“Relatively simple” configuration
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Wait, we need more than code!
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Set up an account

Install the CLI
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Regions? AZ’s?

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IAM?

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Required values can be set in code!

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… or on the command line!

NOW it’s “Hello world” time!
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Hello World! (including ILambdaContext)

Deploying “Hello-World”
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Running deploy-function & invoke-function

Calling our “Hello” function
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We can use the ‘Amazon’ NuGet package(s)

We can use AWS SNS
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We can use any ‘webhook’-type integration
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Creating a “Hello-World-Caller”
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Pretty straightforward using the SDK

Just F5 in VS Code!
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Larger architectures?
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Our “infra team” had a fun exercise...
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CloudFormation - scripted infrastructure
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Normally looks like this...
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… but can also look like this!
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“Add trigger” to your Lambda
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Pick your integration - whatever you want!
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Or just, “deploy-serverless” with the CLI
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AWS Serverless Application Model
http://github.com/awslabs/ 42
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http://serverless.com/framework/docs/
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So, what does this mean for Coolblue?
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This makes it look simple!
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Let’s recap some “gotchas”
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Timings can vary wildly!

Default values can bite you!
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Know your costs! 800,000 sec = 9.25 days
https://aws.amazon.com/lambda/pricing/ 49
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Almost everything is case-sensitive!
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PS> dotnet lambda deploy-function HelloWorld-EUWest
# New Lambda function created
PS> dotnet lambda invoke-function helloworld-euwest -p "Pat"
# Error invoking Lambda function: Function not found:
arn:aws:lambda:eu-west-1:955206359773:function:helloworld-euwest

‘ILambdaContext’ should ALWAYS be last
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public string SayHi(ILambdaContext context, string name = "World")
{
// … do something
}
RESPONSE: (only on invocation, after deployment)
{
"errorType": "LambdaException",
"errorMessage":
"Method 'SayHi' of type 'MyFirstLambdaFunction.HelloWorld' is not supported:
the method has 2 parameters, but the second parameter is not of type
'Amazon.Lambda.Core.ILambdaContext'."
}

Read the FAQ’s!
https://aws.amazon.com/lambda/faqs/ 52
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Q: How are compute resources assigned to an AWS
Lambda function?
In the AWS Lambda resource model, you choose the amount of memory
you want for your function, and are allocated proportional CPU power and
other resources.
For example, choosing 256MB of memory allocates approximately twice as
much CPU power to your Lambda function as requesting 128MB of memory
and half as much CPU power as choosing 512MB of memory. You can set your
memory in 64MB increments from 128MB to 1.5GB.

Containers can be reused!
https://aws.amazon.com/blogs/compute/container-reuse-in-lambda/ 53
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Handy links
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Tooling
● https://github.com/aws/aws-sdk-net/
● https://github.com/aws/aws-lambda-dotnet/
Documentation
● http://github.com/awslabs/
● http://serverless.com/framework/docs/
● https://aws.amazon.com/lambda/faqs/

https://aws.amazon.com/documentation/
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Thanks!
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Tonight’s demos are on GitHub (but they’re really nothing special!)
● https://github.com/pheonix25/lambda-helloworld
● https://github.com/pheonix25/lambda-helloworldcaller

Thanks!
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