Mitch Pierias MitchPierias

OOO in Distributed Applications

For security reasons, it's important to remember the order of which you perform operations within the actions of your distrubuted application.

Checks
Effects
Interactions

Performing operations in this order will prevent the vulnerability seen in the infamous DAO hack (Google it), where an attacker opened a series of withdrawals, and transfered funds before the contract could update it's balance data.

Deploying a Neo4j Instance on Amazon EC2

Instance Setup

IAM Credentials

Ensure you have an IAM user created with correct EC2 or more access for the individual or machine you are wokring on and add your IAM User credentials into ~/.ssh/credentials

Instance Access credentials

Download .pem file and chmod 400 YOUR_CREDENTIALS.pem.

Prerequisites

ArangoDB Deployment to EC2

Install Docker

Update exisitn gpackage list and then install prerequieites.

sudo apt update
sudo apt install apt-transport-https ca-certificates curl software-properties-common

Install GPG for the offical Docker release;

If you are using homebrew, then you can install the latest released stable version of ArangoDB using brew as follows:

brew install arangodb

This will install the current stable version of ArangoDB and all dependencies within your Homebrew tree. Note that the server will be installed as:

/usr/local/Cellar/arangodb/3.4.0/sbin/arangod

You can start the server by running the command:

Nginx reverse proxy for Docker

This was created to help expose ports for an ArangoDB container running on a Ubuntu EC2 instance

For this example, let's assume the container we want to expose is called arangodb-instance, our Nginx instance will be nginx, and our network will be called reverse-proxy. Start by creating our new network.

docker network create reverse-proxy

Next we need to connect our network to the exisitng container we would like to expose.

ArangoDB Deployment to EC2 Linux Instance

Quickly get an ArangoDB instance running on an Amazon EC2 Linux Instance

Update existing package list and then install prerequieites.

sudo yum update -y

If your running a regular amazon linuz instance

sudo yum install docker

Amazon AWS Kubernetes Setup

Amazon's manage Kubernetes service, EKS, uses kubectl along with aws-iam-authenticator extension for clsuter authentication. This gist assumes you have the AWS command line tools and SDK already installed and configured. The aws-iam-authenticator uses the same AWS credential provider chain shared by aws-cli and aws-sdk. To check the configured credentials, run

aws sts get-caller-identity

Installation

Download and install Kubernetes Kubernetes download and install instructions

Animations in React

Avoid using props to continuously update components

The Wrong Way

Before we talk about the right way, let's talk a little bit about how you should not handle animations in React.

References

Use React.createRef to animate elements and then trigger a component on complete.

Context, not Redux

This is a rough project flow we use when taking on new tasks;

Build your UI elements (Storybook) or adjustments based on any mocks in your card.
Integrate elements into the application, making it a dynamic component.
Create tests and run localized testing on all files you've touched yarn test:all --watch ~/path/to/file --coverage false
Turn coverage on and address missing lines in your tests yarn test:all --watch ~/path/to/file --coverage. You might need to add --updateSnapshot to your local tests if you've modified the outputted component and receive snapshot errors.

Alternate back and forth between addressing coverage and fixing tests until all local tests pass.5. Once everything passes locally and coverage is high, run a unit test on the entire project

	# the endpoint upon which to listen for incoming connections (eosio::bnet_plugin)
	bnet-endpoint = 0.0.0.0:4321

	# the number of threads to use to process network messages (eosio::bnet_plugin)
	# bnet-threads =

	# remote endpoint of other node to connect to; Use multiple bnet-connect options as needed to compose a network (eosio::bnet_plugin)
	# bnet-connect =

	# this peer will request no pending transactions from other nodes (eosio::bnet_plugin)