How to run AWS Lambda dotnet on localstack

Question

The DotNet3.1 AWS Lambda

I have created an AWS Lambda solution with C# DotNet3.1 using the Amazon template

dotnet new serverless.AspNetCoreWebAPI -n MyDotNet.Lambda.Service

this creates a lambda function whose handler is MyDotNet.Lambda.Service::MyDotNet.Lambda.Service.LambdaEntryPoint::FunctionHandlerAsync plus some serverless.template file and aws-lambda-tools-defaults.json

The standard way to deploy the DotNet3.1 AWS Lambda

The standard way to deploy it would be to install Amazon.Lambda.Tools

dotnet tool update -g Amazon.Lambda.Tools

and then run

dotnet lambda deploy-serverless --profile myawsprofile

Notice that the profile is optional, but I've got AWS configured under that profile. This will prompt for CloudFormation Stack Name (e.g: foo) and a S3 bucket (e.g: my-bucket) and will deploy it to the "real" AWS configured under the custom profile myawsprofile

LocalStack running as a docker container

All good so far. Now I have just discovered https://github.com/localstack/localstack which is a great way to run AWS platform locally, so I use docker-compose file localstack-compose.yml to spin up the container

version: '3.8'

services:
  localstack:
    container_name: "${LOCALSTACK_DOCKER_NAME-localstack_main}"
    image: localstack/localstack-full
    network_mode: bridge
    ports:
      - "4566:4566"
      - "4571:4571"
      - "${PORT_WEB_UI-8080}:${PORT_WEB_UI-8080}"
    environment:
      - SERVICES=${SERVICES- }
      - DEBUG=${DEBUG- }
      - DATA_DIR=${DATA_DIR- }
      - PORT_WEB_UI=${PORT_WEB_UI- }
      - LAMBDA_EXECUTOR=${LAMBDA_EXECUTOR- }
      - KINESIS_ERROR_PROBABILITY=${KINESIS_ERROR_PROBABILITY- }
      - DOCKER_HOST=unix:///var/run/docker.sock
      - HOST_TMP_FOLDER=${TMPDIR}
    volumes:
      - "${TMPDIR:-/tmp/localstack}:/tmp/localstack"
      - "/var/run/docker.sock:/var/run/docker.sock"

Like this:

docker-compose -f localstack-compose.yml up

And it runs all under the port 4566

AWS Local

In order to run AWS CLI with LocalStack I install the wrapper https://github.com/localstack/awscli-local so that I can do things like

awslocal s3 ls

How do I deploy the AWS Lambda locally?

I am too new to understand most of the tutorials I've followed. Some of them refer to serverless framework, but I am just using localstack as a docker container. I've also installed SAM CLI in case it's needed (although I don't yet understand what's for)

I've tried deploying it to the local stack with

dotnet lambda deploy-serverless --profile default

which would be the equivalent, I think, but I get

Error uploading to MyDotNet.Lambda.Service/AspNetCoreFunction-CodeUri-Or-ImageUri-637509113851513062-637509113886357582.zip in bucket foo: The bucket you are attempting to access must be addressed using the specified endpoint. Please send all future requests to this endpoint

although I have a bucket s3://foo in localstack

It's really complicated to find an example I can follow with my basic level of AWS knowledge. Is there any instructions I've missed, or a nice link/tutorial on how to achieve what I want step by step? Thanks

UPDATE 1 (11/3/2021) I've tried step by step with a web api project created with Amazon template https://gitlab.com/sunnyatticsoftware/sandbox/localstack-sandbox/-/tree/master/02-lambda-dotnet-webapi

but I find problems.

Steps: First I create role for lambda execution

awslocal iam create-role --role-name lambda-dotnet-webapi-ex --assume-role-policy-document file://trust-policy.json

Attach policy to the role to grant permission for execution

awslocal iam attach-role-policy --role-name lambda-dotnet-webapi-ex --policy-arn arn:aws:iam::aws:policy/service-role/AWSLambdaBasicExecutionRole

Create Lambda function

awslocal lambda create-function --function-name lambda-dotnet-webapi-function --zip-file fileb://function.zip --handler Sample.Lambda.DotNet.WebApi::Sample.Lambda.DotNet.WebApi.LambdaEntryPoint::FunctionHandlerAsync --runtime dotnetcore3.1 --role arn:aws:iam::000000000000:role/lambda-dotnet-webapi-ex

Invoke the AWS Lambda using the base64 utility to decode the logs

awslocal lambda invoke --function-name lambda-dotnet-webapi-function out --log-type Tail --query 'LogResult' --output text | base64 -d

It returns:

iptables v1.4.21: can't initialize iptables table `nat': iptables who? (do you need to insmod?)
Perhaps iptables or your kernel needs to be upgraded.
info: Microsoft.Hosting.Lifetime[0]
      Application started. Press Ctrl+C to shut down.
[Information] Microsoft.Hosting.Lifetime: Application started. Press Ctrl+C to shut down.
[Information] Microsoft.Hosting.Lifetime: Hosting environment: Production
[Information] Microsoft.Hosting.Lifetime: Content root path: /var/task
info: Microsoft.Hosting.Lifetime[0]
      Hosting environment: Production
info: Microsoft.Hosting.Lifetime[0]
      Content root path: /var/task
START RequestId: a5eb1d2d-d908-15f6-ace3-d4d0e01a0066 Version: $LATEST
Could not load file or assembly 'System.IO.Pipelines, Version=4.0.2.1, Culture=neutral, PublicKeyToken=cc7b13ffcd2ddd51'. The system cannot find the file specified.
: FileNotFoundException
   at Amazon.Lambda.AspNetCoreServer.AbstractAspNetCoreFunction`2.FunctionHandlerAsync(TREQUEST request, ILambdaContext lambdaContext)
   at System.Runtime.CompilerServices.AsyncMethodBuilderCore.Start[TStateMachine](TStateMachine& stateMachine)
   at Amazon.Lambda.AspNetCoreServer.AbstractAspNetCoreFunction`2.FunctionHandlerAsync(TREQUEST request, ILambdaContext lambdaContext)
   at lambda_method(Closure , Stream , Stream , LambdaContextInternal )


END RequestId: a5eb1d2d-d908-15f6-ace3-d4d0e01a0066
REPORT RequestId: a5eb1d2d-d908-15f6-ace3-d4d0e01a0066  Init Duration: 2305.87 ms       Duration: 33.29 ms      Billed Duration: 100 ms      Memory Size: 1536 MB    Max Memory Used: 0 MB
Starting daemons...
ImportError: No module named site

Does anybody have a working example?

UPDATE 2 The interesting thing is that I've tried against the REAL AWS (a different profile in AWS credentials) and I also get an error, but it's different.

Create role

aws iam create-role --role-name lambda-dotnet-webapi-ex --assume-role-policy-document file://trust-policy.json --profile diegosasw

List roles

aws iam list-roles --profile diegosasw

Attach policy

aws iam attach-role-policy --role-name lambda-dotnet-webapi-ex
 --policy-arn arn:aws:iam::aws:policy/service-role/AWSLambdaBasicExecutionRole --profile diegosasw

Create lambda

aws lambda create-function --function-name lambda-dotnet-webap
i-function --zip-file fileb://function.zip --handler Sample.Lambda.DotNet.WebApi::Sample.Lambda.DotNet.WebApi.LambdaEntryPoint::FunctionHa
ndlerAsync --runtime dotnetcore3.1 --role arn:aws:iam::308309238958:role/lambda-dotnet-webapi-ex --profile diegosasw

Invoke

aws lambda invoke --function-name lambda-dotnet-webapi-function --profile diegosasw out --log-type Tail --query 'LogResult' --output text | base64 -d

It returns

START RequestId: 7d77489f-869b-4e4d-87a0-ac800d71eb2d Version: $LATEST
warn: Amazon.Lambda.AspNetCoreServer.AbstractAspNetCoreFunction[0]
      Request does not contain domain name information but is derived from APIGatewayProxyFunction.
[Warning] Amazon.Lambda.AspNetCoreServer.AbstractAspNetCoreFunction: Request does not contain domain name information but is derived from APIGatewayProxyFunction.
Object reference not set to an instance of an object.: NullReferenceException
   at Amazon.Lambda.AspNetCoreServer.APIGatewayProxyFunction.MarshallRequest(InvokeFeatures features, APIGatewayProxyRequest apiGatewayRequest, ILambdaContext lambdaContext)
   at Amazon.Lambda.AspNetCoreServer.AbstractAspNetCoreFunction`2.FunctionHandlerAsync(TREQUEST request, ILambdaContext lambdaContext)
   at lambda_method(Closure , Stream , Stream , LambdaContextInternal )


END RequestId: 7d77489f-869b-4e4d-87a0-ac800d71eb2d
REPORT RequestId: 7d77489f-869b-4e4d-87a0-ac800d71eb2d  Duration: 755.06 ms     Billed Duration: 756 ms Memory Size: 128 MB     Max Memory Used: 87 MB    Init Duration: 462.09 ms

Answer 1

I got it working both for AWS and LocalStack (i.e: awslocal). Here are the steps using just AWS CLI. Here's the repo sample https://gitlab.com/sunnyatticsoftware/sandbox/localstack-sandbox/-/tree/master/03-lambda-dotnet-empty

Create AWS lambda in localstack with AWS CLI

AWS

Create empty sample C# lambda function from an Amazon template

dotnet new lambda.EmptyFunction -n Sample.Lambda.DotNet

Compile and publish

dotnet build
dotnet publish -c Release -o publish

Zip lambda files

cd publish
zip -r ../function.zip *

Create role

aws --profile diegosasw iam create-role --role-name lambda-dotnet-ex --assume-role-policy-document '{"Version": "2012-10-17", "Statement": [{ "Effect": "Allow", "Principal": {"Service": "lambda.amazonaws.com"}, "Action": "sts:AssumeRole"}]}'

Attach AWSLambdaBasicExecutionRole policy to role

aws --profile diegosasw iam attach-role-policy --role-name lambda-dotnet-ex --policy-arn arn:aws:iam::aws:policy/service-role/AWSLambdaBasicExecutionRole

Create lambda

aws --profile diegosasw lambda create-function --function-name lambda-dotnet-function --zip-file fileb://function.zip --handler Sample.Lambda.DotNet::Sample.Lambda.DotNet.Function::FunctionHandler --runtime dotnetcore3.1 --role arn:aws:iam::308309238958:role/lambda-dotnet-ex

Invoke lambda

aws --profile diegosasw lambda invoke --function-name lambda-dotnet-function --payload "\"Just Checking If Everything is OK\"" response.json --log-type Tail

LocalStack

For localStack is similar, but replacing aws with awslocal, of course, and I don't specify any profile but you can use --profile default or whichever you have your .aws/credentials at

Create role

awslocal iam create-role --role-name lambda-dotnet-ex --assume-role-policy-document '{"Version": "2012-10-17", "Statement": [{ "Effect": "Allow", "Principal": {"Service": "lambda.amazonaws.com"}, "Action": "sts:AssumeRole"}]}'

Attach AWSLambdaBasicExecutionRole policy to role

awslocal iam attach-role-policy --role-name lambda-dotnet-ex --policy-arn arn:aws:iam::aws:policy/service-role/AWSLambdaBasicExecutionRole

Create lambda

awslocal lambda create-function --function-name lambda-dotnet-function --zip-file fileb://function.zip --handler Sample.Lambda.DotNet::Sample.Lambda.DotNet.Function::FunctionHandler --runtime dotnetcore3.1 --role arn:aws:iam::000000000000:role/lambda-dotnet-ex

Invoke lambda in localstack passing a json payload (string is valid JSON)

awslocal lambda invoke --function-name lambda-dotnet-function --payload "\"Just Checking If Everything is OK again\"" response.json --log-type Tail

View functions

awslocal lambda list-functions

Delete function

awslocal lambda delete-function --function-name lambda-dotnet-function

Dotnet tool

With dotnet tool, the equivalent is

dotnet lambda invoke-function lambda-dotnet-function --payload "Just Checking If Everything is OK" --profile diegosasw