Atadzhan Dzhan85

PSQL

Magic words:

psql -U postgres

Some interesting flags (to see all, use -h or --help depending on your psql version):

-E: will describe the underlaying queries of the \ commands (cool for learning!)
-l: psql will list all databases and then exit (useful if the user you connect with doesn't has a default database, like at AWS RDS)

Problem

I have two Github accounts: oanhnn (personal) and superman (for work). I want to use both accounts on same computer (without typing password everytime, when doing git push or pull).

Solution

Use ssh keys and define host aliases in ssh config file (each alias for an account).

How to?

Generate ssh key pairs for accounts and add them to GitHub accounts.

Handling Multiple Github Accounts on MacOS

The only way I've succeeded so far is to employ SSH.

Assuming you are new to this like me, first I'd like to share with you that your Mac has a SSH config file in a .ssh directory. The config file is where you draw relations of your SSH keys to each GitHub (or Bitbucket) account, and all your SSH keys generated are saved into .ssh directory by default. You can navigate to it by running cd ~/.ssh within your terminal, open the config file with any editor, and it should look something like this:

Host *
 AddKeysToAgent yes

> UseKeyChain yes

Deploying a Production ready React-Express app on AWS

In this tutorial, I will be going over to how to deploy a Javascript app from start to finish using AWS and EC2. Recently, my partner Tu and I launched our app AlgoAcademy (a resource for reviewing algorithms and data structures) and we wanted to share with other developers some of the lessons we learned along the way.

Following this tutorial, you will have an application that has:

A React frontend, Express backend
An AWS EC2 server configured to host your application
SSL-certification with Certbot
A custom domain name

ELK (Elasticsearch Logstash Kibana)

Though we're focused more on server setup procedure in this document, I will still give a very brief explanation in laymen terms for ELK. To those who are starting new in this stack, must have already heard of MVC (Model View Controller), so take it like this:

Model => Elasticsearch (for Storage, Indexing & Search)
View => Kibana (for DataViz & G-Man, yeah the one in half life 😏)
Controller => Logstash (For Logs & Filtering)

Prerequirements:

Have Elasticseach + Kibana installed
Have server.basePath: "/kibana" option configured in your kibana.yml file

i. Install NGINX apt install nginx

ii. Modify nginx.conf

In /etc/nginx/nginx.conf you should have a similar setup:


	Questions are not from any actual exam!!!



	Q: Create a job that calculates pi to 2000 decimal points using the container with the image named perl
	and the following commands issued to the container: ["perl", "-Mbignum=bpi", "-wle", "print bpi(2000)"]
	Once the job has completed, check the logs to and export the result to pi-result.txt.

	Solution:

	#!/bin/bash
	# Install docker
	apt-get update
	apt-get install -y cloud-utils apt-transport-https ca-certificates curl software-properties-common
	curl -fsSL https://download.docker.com/linux/ubuntu/gpg \| sudo apt-key add -
	add-apt-repository \
	"deb [arch=amd64] https://download.docker.com/linux/ubuntu \
	$(lsb_release -cs) \
	stable"
	apt-get update