mugli

Studying for a Tech Interview Sucks, so Here's a Cheat Sheet to Help

This list is meant to be a both a quick guide and reference for further research into these topics. It's basically a summary of that comp sci course you never took or forgot about, so there's no way it can cover everything in depth. It also will be available as a gist on Github for everyone to edit and add to.

Data Structure Basics

###Array ####Definition:

• Stores data elements based on an sequential, most commonly 0 based, index.
• Based on tuples from set theory.

mugli

# Delete all containers
docker rm $(docker ps -aq)
# Delete all images
docker rmi $(docker images -q)
# Delete all untagged images
docker rmi $(docker images -q --filter "dangling=true")

References:

mugli

• http://the-paper-trail.org/blog/distributed-systems-theory-for-the-distributed-systems-engineer/
• https://github.com/palvaro/CMPS290S-Winter16/blob/master/readings.md
• http://muratbuffalo.blogspot.com/2015/12/my-distributed-systems-seminars-reading.html
• http://christophermeiklejohn.com/distributed/systems/2013/07/12/readings-in-distributed-systems.html
• http://michaelrbernste.in/2013/11/06/distributed-systems-archaeology-works-cited.html
• http://rxin.github.io/db-readings/
• http://research.microsoft.com/en-us/um/people/lamport/pubs/pubs.html
• http://pdos.csail.mit.edu/dsrg/papers/
• http://scalingsystems.com/2011/09/07/reading-list-for-distributed-systems/
• http://courses.engr.illinois.edu/cs525/sp2011/sched.htm

mugli

I use PostgreSQL via the psql client. If you use a different client (eg. pgAdmin, etc.), I don't know how much will translate over.

One nice difference between psql and mysql (cli) is that if you press CTRL+C, it won't exit the client.

User administration

Login as superuser (via shell)

psql -U postgres

mugli

# Elasticsearch Cheatsheet - an overview of commonly used Elasticsearch API commands

# cat paths
/_cat/allocation
/_cat/shards
/_cat/shards/{index}
/_cat/master
/_cat/nodes
/_cat/indices
/_cat/indices/{index}

mugli

default['sshd']['sshd_config']['AuthenticationMethods'] = 'publickey,keyboard-interactive:pam'
default['sshd']['sshd_config']['ChallengeResponseAuthentication'] = 'yes'
default['sshd']['sshd_config']['PasswordAuthentication'] = 'no'

mugli

MicroService Proxy Gateway Solutions

Kong, Traefik, Caddy, Linkerd, Fabio, Vulcand, and Netflix Zuul seem to be the most common in microservice proxy/gateway solutions. Kubernetes Ingress is often a simple Ngnix, which is difficult to separate the popularity from other things.

Github Star Trend:

This is just a picture of this link from March 2, 2019

Originally, I had included some other solution

mugli

Kafka Cheat Sheet

Display Topic Information

$ kafka-topics.sh --describe --zookeeper localhost:2181 --topic beacon
Topic:beacon	PartitionCount:6	ReplicationFactor:1	Configs:
	Topic: beacon	Partition: 0	Leader: 1	Replicas: 1	Isr: 1
	Topic: beacon	Partition: 1	Leader: 1	Replicas: 1	Isr: 1

mugli

• What do Etcd, Consul, and Zookeeper do?
  • Service Registration:
    • Host, port number, and sometimes authentication credentials, protocols, versions numbers, and/or environment details.
  • Service Discovery:
    • Ability for client application to query the central registry to learn of service location.
  • Consistent and durable general-purpose K/V store across distributed system.
    • Some solutions support this better than others.
    • Based on Paxos or some derivative (i.e. Raft) algorithm to quickly converge to a consistent state.
• Centralized locking can be based on this K/V store.

mugli

SELECT id, concat('kill ', id, ';') as kill_command, state, command, time, info
FROM information_schema.processlist
WHERE command <> 'Sleep' 
AND info NOT LIKE '%PROCESSLIST%'
ORDER BY time DESC LIMIT 50;