tsiege

ANNOUNCEMENT

I have moved this over to the Tech Interview Cheat Sheet Repo and has been expanded and even has code challenges you can run and practice against!






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vasanthk

System Design Cheatsheet

Picking the right architecture = Picking the right battles + Managing trade-offs

Basic Steps

1. Clarify and agree on the scope of the system

• User cases (description of sequences of events that, taken together, lead to a system doing something useful)
  • Who is going to use it?
  • How are they going to use it?

ursuad

Kafka Topics

List existing topics

bin/kafka-topics.sh --zookeeper localhost:2181 --list

Describe a topic

bin/kafka-topics.sh --zookeeper localhost:2181 --describe --topic mytopic

Purge a topic

bin/kafka-topics.sh --zookeeper localhost:2181 --alter --topic mytopic --config retention.ms=1000

... wait a minute ...

vkroz

Kafka frequent commands

Assuming that the following environment variables are set:

• KAFKA_HOME where Kafka is installed on local machine (e.g. /opt/kafka)
• ZK_HOSTS identifies running zookeeper ensemble, e.g. ZK_HOSTS=192.168.0.99:2181
• KAFKA_BROKERS identifies running Kafka brokers, e.g. KAFKA_BROKERS=192.168.0.99:9092

Server

Start Zookepper and Kafka servers

lummie

package enum_example

import (
	"bytes"
	"encoding/json"
)

// TaskState represents the state of task, moving through Created, Running then Finished or Errorred
type TaskState int

dwickern

import org.scalatest._

sealed trait Repeated extends TestSuiteMixin { this: TestSuite =>
  protected abstract override def runTest(testName: String, args: Args): Status = {
    def run0(times: Int): Status = {
      val status = super.runTest(testName, args)
      if (times <= 1) status else status.thenRun(run0(times - 1))
    }

    run0(args.configMap.getWithDefault("times", "1").toInt)

sahilsk

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

sghiassy

Disable Device Enrollment Notification on Mac.md

Restart the Mac in Recovery Mode by holding Comment-R during restart

Open Terminal in the recovery screen and type

csrutil disable

procrastinatio

Introduction

So HAProxy is primalery a load balancer an proxy for TCP and HTTP. But it may act as a traffic regulator. It may also be used as a protection against DDoS and service abuse, by maintening a wide variety of statistics (IP, URL, cookie) and when abuse is happening, action as denying, redirecting to other backend may undertaken ([haproxy ddos config], [haproxy ddos])

marwei

Kafka 0.11.0.0 (Confluent 3.3.0) added support to manipulate offsets for a consumer group via cli kafka-consumer-groups command.

1. List the topics to which the group is subscribed

kafka-consumer-groups --bootstrap-server <kafkahost:port> --group <group_id> --describe

Note the values under "CURRENT-OFFSET" and "LOG-END-OFFSET". "CURRENT-OFFSET" is the offset where this consumer group is currently at in each of the partitions.

2. Reset the consumer offset for a topic (preview)