• OAuth2 Primer

    First post of the year 2018, here is the presentation for a tech talk on OAuth2 at Marqeta HQ.

    Read on →

  • Multiple Functions in Serverless Framework with Java

    Serverless Framework is an excellent choice for writing and deploying Lambda Functions in AWS. Having written a blog series on using it with Java8+Maven, I’ve been asked if there is a way to not have too many handlers (One per API), and somehow provide multiple handler functions in the same java class. In this post I provide the structure that’d allow for multiple handlers using a single Java class.

    This is particularly useful when the code is tightly coupled around a resource (CRUD) and writing a handler class for each of C, R, U, D seems un-necessary, like it should.

    Read on →

  • HTTP/S Proxy Server for AWS Lambda Invocations

    Lambda Functions are a FaaS implementation on Amazon Web Services. Setting them as HTTP/S endpoints over API Gateway can be complicated, and more often than not is an overkill for simple, internal APIs. Besides, API Gateway endpoints for Lambda are public, no matter how we slice and dice it. The recently announced VPC Link for API Gateway only allows the endpoints to route to a NLB target, not a Lambda.

    This is a lightweight HTTP/S proxy written in Java, which wraps a lambda invocation, mimicking the API Gateway-Lambda Proxy Integration.

    Read on →

  • Run tasks with AWS Fargate and Lambda

    As with any other financial company, at Marqeta, we have a good number of batch jobs, which we are migrating over to AWS Batch. However, even in managed mode, AWS Batch needs us to define Compute Environments, which are clusters of EC2 instances running ECS (and Docker) agents.

    AWS Fargate was announced very recently at re:Invent 2017. Fargate adds a layer of abstraction on top of the Compute Environment, or the ECS Cluster. We no longer have to worry about the AMI, EC2 types, task placement, etc. In this post I cover the POC done to use Fargate over AWS Batch for batch processing, but this can also be used as a tutorial for running any type of tasks using Fargate. We create an ECS Task definition, a Fargate Cluster, and a Lambda to run the task using CloudWatch Event trigger.


    Read on →

  • Scale By the Bay - Immutable AWS Deployments with Packer and Jenkins

    Slides from my talk at Scale By the Bay 2017.

    In this session I will talk about Immutable Deployments - which have become almost essential in the world of Microservices. As the frequency of deployments across multiple services increases with increasing granularity, it is critical to have repeatable, predictable and immutable deployments serving our customers. In practice, this is achieved via several DevOps tools. We will use Hashicorp Packer and Jenkins to build a simple, immutable AWS deployment of a hello-world microservice. Familiarity with AWS is recommended, but not required for this talk.

    Read on →