Serverless Orchestrator of Serverless Workers

`sosw`:

Framework to simplify the design of AWS Lambda functions in Python
Set of tools for orchestrating asynchronous invocations of AWS Lambda functions.

Essential components of `sosw` orchestration are implemented as AWS Lambda functions themselves.

Note

Please pronounce sosw correctly: /ˈsɔːsəʊ/

Essential Workflow Schema

Workers

The Worker functions themselves are your functions that require Orchestration. sosw package has multiple components and tools that we encourage you to use in your Workers to make the code DRY and stable: statistic aggregation, components initialization, configuration automatic assembling and more…

In order to be Orchestrated by sosw, the functions should be able to mark tasks they receive as completed once the job is done. If you inherit the main classes of your Lambdas from Worker this will be handled automatically. The default behaviour of Workers is not to touch the queue, but to call a Worker Assitant lambda to mark tasks as completed.

Scheduling

Scheduling is transformation of your business jobs to specific tasks for Lambda Worker. One task = one invocation of a Worker. Scheduler provides an interface for your Business Applications, other Lambdas, Events (e.g. Scheduled Rules) to provide the Business Job.

Chunking of the Payload happens following the rules that you pre-configure. One of the built-in dimensions for chunking is calendar.

Scheduled tasks go to a stateful queue to be invoked when the time comes.

Orchestration

The Orchestrator is called automatically every minute by Scheduled Events. It evaluates the status of Workers at the current moment, the health of external metrics the Workers may depend on (e.g CPU lod of some DB, IOPS, etc.) and invokes the appropriate amount of new parallel invocations.

Scavenger

The Scavenger is called automatically every minute by Scheduled Events. It collects the tasks marked as completed by the Workers and archives them.

If the task did not successfully accomplish it tries to re-invoke it with configurable exponential delay. In case the task completely fails after several invocations, the Scavenger marks it is dead and removes from the queue to avoid infinite retries. In this case some external alarm system: SNS or Lambda may be triggered as well.

Installation

Installation

`sosw` requires you to implement/deploy several Lambda functions (Essentials) using the appropriate core classes. The deployment is described in details, but assumes that you are familiar with basic AWS Serverless products.

Another deployment requirement is to create several DynamoDB tables.

You can find the Cloudformation template for the databases in the example.

If you are not familiar with CloudFormation, we highly recommend at least learning the basics from the tutorial.

Once again, the detailed guide for initial setup can be found in the Installation.