Darkowl

An infrastructure-forward modern worker template built with Rust for AWS Lambda

Building the lambda

cargo build --release --target x86_64-unknown-linux-musl

Testing the Lambda Locally

1. Run the lambda ci docker image

docker run --rm \
-e DOCKER_LAMBDA_STAY_OPEN=1 -p 9001:9001 \
-v "$PWD"/target/x86_64-unknown-linux-musl/release/bootstrap:/var/task/bootstrap:ro,delegated \
lambci/lambda:provided main

2. In a separate terminal, invoke the lambda

aws lambda invoke \
--endpoint http://localhost:9001 \
--no-sign-request --function-name=darkowl \
--invocation-type=RequestResponse \
--payload $(echo '{ "externalRequester": "cron" }' | base64 ) \
output.json

Set up for Deploys

1. Ensure you have a command line role belonging to a group with IAMFullAccess, and LambdaFullAccess

2. Using that role, run:

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

3. Then:

aws iam attach-role-policy \
--role-name lambda-basic-execution \
--policy-arn arn:aws:iam::aws:policy/service-role/AWSLambdaBasicExecutionRole

Deploying

1. Zip the build

zip -r9 -j bootstrap.zip ./target/x86_64-unknown-linux-musl/release/bootstrap

2. Deploy to a new function

AWS_ACCOUNT_ID=`aws sts get-caller-identity --query Account --output text` && \
aws lambda create-function \
--function-name darkowl \
--runtime provided \
--role arn:aws:iam::$AWS_ACCOUNT_ID:role/lambda-basic-execution \
--zip-file fileb://bootstrap.zip \
--description "Simple Rust function" \
--timeout 5 \
--handler main

Updating the Deployed Function

1. Rebuild

2. Rezip

3. Run:

aws lambda update-function-code --function-name darkowl --zip-file fileb://bootstrap.zip

Configuring the lambda to run on a schedule

1. Add the Cloudwatch rule

aws events put-rule \
--name darkowl-schedule \
--schedule-expression 'rate(5 minutes)'

2. Give the rule permission to invoke your function

aws lambda add-permission \
--function-name darkowl \
--statement-id my-scheduled-event \
--action 'lambda:InvokeFunction' \
--principal events.amazonaws.com \
--source-arn {your_rule_arn}

3. Create a targets.json file for the rule

[
  {
    "Id": "1", 
    "Arn": "{your_lambda_arn}"
  }
]

4. Add the targets to your rule

aws events put-targets --rule darkowl-schedule --targets file://targets.json