Musings, Ruby

• bundle add <GEM_NAME> to add a gem plus its latest version. Problem is it’s added at the bottom of the file.
• representable: Something for APIs?
• bitcoiner gems:
  • typhoeus: Wraps libcurl to make fast/reliable requests.
  • addressable: A replacement for the URI implementation in Ruby’s standard library. Instead of URI, Addressable::URI.
• Electrum: A bitcoin wallet.
• rack-attack: This can help in rate limiting.
• Timeouts
  • Postgres has a statement_timeout for a database user. This thing executes even while just connecting to the database.

Trying out message_bus

• It depends on Redis by default. You can use Postgres or memory to store the queue.
• You can double subscribe? Hehe. Where do you put this in Rails? I imagine it must be in some sort of initializer or in a process somewhere.
• Evaluating Ruby pub/sub gems.
  • message_bus.
  • Ruby to do web sockets? The migration path from Ruby to Node is not pretty and is full of problems.
  • RabbitMQ.
  • Wisper is great for notifications, but where it falls down is it makes you put a million pieces together in an app. message_bus.
  • Firehose: Tied to HTTP, expects clients to be in JS and servers to be in Ruby, and something oriented around the metaphor of a path-oriented queue.
  • RabbitMQ + Bunny + Sneakers.
• Observer vs Pub-Sub pattern:
  • Observer: knows its dependencies.
  • Publisher-Subscriber: Senders of messages, called publishers, do not program the messages to be sent directly to specific receivers, called subscribers.
  • Third component: broker or message broker or event bus, which filters all incoming messages and distributes them accordingly.
  • Pub-sub is a pattern used to communicate messages between different system components without these components knowing anything about each other’s identity.

Musings, AWS

• Docker packages software into standardized units called Containers: containers allow you to easily package an application’s code, config, and dependencies into easy to use building blocks that deliver environmental consistency, operational efficiency, developer productivity, and version control.
• Container vs virtual machines: Only contains the app and dependencies. No file system/VM.
• Container Benefits:
  • Escape from Dependency Hell
  • Consistent progression from dev → test → QA → prod.
  • Isolation between container A and B.
  • Better resource management.
  • Extreme code portability.
  • Makes it easy to microservice.
• Components:
  • Docker image: Contains only the files required to boot a container.
  • Docker container: Contains the things an app needs to run.
  • Layers/union file systems: Read-only templates for which containers are launched. They combine to a single image. When you update, you don’t need to
  • Dockerfile: Images built from the base image using specific instructions: run a command, add a file, add a directory. Docker reads this Dockerfile when you need this image.
  • Docker Daemon/Engine:
  • Docker Client: The interface between you and the engine.
  • Docker Registries/Docker Hub: Holds images. Private/public image collections.
• ECS: Amazon EC2 Container Service (Amazon ECS) is a highly scalable, fast, container management service that makes it easy to run, stop, and manage Docker containers on a cluster of EC2 instances.
  • Use an API call to launch/stop container-based applications.
  • Get the state of the cluster.

What is ECS?

• Elastic Container Service
  • Able to be used in one or more AZs across a new/existing VPC to schedule the placement of containers across your cluster.
  • Eliminates the need for you to operate your own cluster management/config management.
  • Used to create a consistent deployment and build experience, manage and scale batch and ETL workloads, and build sophisticated application architectures on a microservices model.
• Docker: Just like CloudFormation, it’s a way to set up your container.
• ECR: EC2 Container Registry, you can put private Docker repos there.
• ECS Task Definitions: Text files that describe one or more containers that form your application.