Azure Devops, Azure, YAML, Conditional Tasks

https://docs.microsoft.com/en-us/azure/devops/pipelines/process/conditions?view=azure-devops&tabs=yaml

When we specify Condition, we actually make the execution of step conditional to the outcome of execution of previous step.

You can specify conditions under which a step, job, or stage will run.

• Only when all previous dependencies have succeeded. This is the default if there is not a condition set in the YAML.

• Even if a previous dependency has failed, unless the run was canceled. Use succeededOrFailed() in the YAML for this condition.

• Even if a previous dependency has failed, even if the run was canceled. Use always() in the YAML for this condition.

• Only when a previous dependency has failed. Use failed() in the YAML for this condition.

• Custom conditions

1 2 3 4 5 6 7 8 9 10

jobs: - job: Foo steps: - script: echo Hello! condition: always() # this step will always run, even if the pipeline is canceled - job: Bar dependsOn: Foo condition: failed() # this job will only run if Foo fails

Azure Devops, Shell Script, YAML

https://docs.microsoft.com/en-us/azure/devops/pipelines/tasks/utility/bash?view=azure-devops

steps:
- task: Bash@3
  inputs:
    targetType: 'inline'
    script: echo $MYSECRET
  env:
    MYSECRET: $(Foo)

Microservices, Fault Tolerance and Resilience - Hystrix - Spring Cloud

https://www.youtube.com/watch?v=o8RO38KbWvA&list=PLqq-6Pq4lTTbXZY_elyGv7IkKrfkSrX5e

#### Spring Boot Microservices Level 2: Fault Tolerance and Resilience  

Fault Tolerance :- How much Tolerance a System has for a particular fault in microservices
Resilience :- How many Faults a System can handle

DNS , Domain Name System - How Domain Name System Works

 

https://www.youtube.com/watch?v=JkEYOt08-rU   [BEST DNS Video]

https://www.netnod.se/i-root/what-are-root-name-servers

Domain Registrar knows which same Set of "Name Servers" your domain points to

Remove current NS and Update NS. It takes max 24 hours before these changes are effective

Recursive Resolver is Provided by ISP - Internet Service Provider (Tata Sky Broadband, Airtel, Jio)

How does TLD Name Server Knows - Which Authoritative Name Server has actual - Ip Adress Mapping 

Because Website Owner(Hosting Provider) configures list of "Authoritative Name Servers" with Domain Registrar

Domain Registrar updates this info with TLD Server- Top Level Domain Name Server

This process usually takes 24 Hours

Who operates them? ROOT NAME Servers

The root servers are operated by 12 different organizations:

• A VeriSign Global Registry Services
• B University of Southern California, Information Sciences Institute
• C Cogent Communications
• D University of Maryland
• E NASA Ames Research Center
• F Internet Systems Consortium, Inc.
• G US DoD Network Information Center
• H US Army Research Lab
• I Netnod
• J VeriSign Global Registry Services
• K RIPE NCC
• L ICANN
• M WIDE Project

Many of these organizations have been operating root servers since the creation of the DNS. The list shows the Internet’s early roots as a US-based research and military network.

Security Group, AWS

Security Group - is attached to EC2 instances /VPC

It Defines :-    Protocol, Rule, Incoming DataFlow Direction, Source CIDR,

Windows EC2 Instances ,Microsoft , Remote Desktop Connection to Microsoft Instances

 PEM = Private Key

Generate password from "Connect to EC2" Dashboard - By Uploading PEM File (Private Key)

Username is "Administrator"

Connect using MSTSC command from any Windows PC

HOW SSD Solid State Drive

https://www.youtube.com/watch?v=5Mh3o886qpg

"Charge Trap Flash Memory Cell"

They trap electrons level within them