citium

Serverless function to trigger a scheduled HTTP request

Requirements

• AWS CLI already configured with AdministratorAccess permission IAM Admin
• AWS SAM CLI installed SAM CLI

Setup process

Building

Compile binary function:

make build

Packaging & Deployment

Prepare a S3 bucket to upload the binary Lambda function:

aws s3 mb s3://citium-builds --profile adminuser

Package Lambda function to S3:

sam package \
    --template-file template.yaml \
    --s3-bucket citium-builds \
    --output-template-file template.output.yaml \
    --profile adminuser

The returned file template.output.yaml now should contain the CodeUri that points to the artifact to be deployed.

Create a Cloudformation Stack and deploy SAM resources:

sam deploy \
    --template-file template.output.yaml \
    --stack-name citium-serverless \
    --capabilities CAPABILITY_IAM \
    --profile adminuser

After the deployment is complete, run the following command to retrieve stack info:

aws cloudformation describe-stacks --stack-name citium-serverless

The dynamodb table name for storing requests is citium_schedule which could be overridden at packing step.

...
Parameters:
  ScheduleTableName:
    Type: String
    Description: Name of the dynamodb table to be created & used by function
    Default: citium_schedule

Default checking interval is 5 minutes.

...
      Events:
        PeriodicCheck:
          Type: Schedule
          Properties:
            Schedule: rate(5 minutes)

Local development

Invoking function locally

sam local invoke TriggerAPIFunction  --no-event --env-vars env.json --debug

NOTE: Template file should be modified before hand with added property CodeUri pointing to current dir

...
  TriggerAPIFunction:
    Type: AWS::Serverless::Function
    Properties:
      CodeUri: ./
      Handler: citium 

Usage

Install CLI tool

Download cli tool from release or compile from source:

make build-tools

Schedule New Request

If persistent=false then the scheduled request will be removed after successfully executed:

./citium-cli \
    -action=create \
    -table=citium_schedule \
    -id=test-post-request \
    -freeze=30m \
    -method=POST \
    -url=http://example.com \
    -headers=Content-Type:application/json \
    -persistent=true

Lock Request

To safely halt request execution, for the case of execution failure that needs manual intervention:

./citium-cli \
    -action=unlock \
    -table=citium_schedule \
    -id=test-delete-resource

Unlock Request

To release the execution lock:

./citium-cli \
    -action=lock \
    -table=citium_schedule \
    -id=test-delete-resource

Extra options

Optional extra values for API request authorization, base url, etc are configured via environment variables:

...
    Environment:
      Variables:
        TABLE_NAME: !Ref ScheduleTableName
        BASE_URL: ""
        API_TOKEN: ""
        USER_AGENT: citium/0.0.1