AZ-400 Chapter 4-6

Question 1

What is centralized source control?

Answer 1

Where only the server has the full history and set of branches.
Users ‘check out’ the latest set of changes only
Allows for tight security control

Question 2

What is decentralized source control?

Answer 2

Where each user has a full copy and the history
Everything can live on a sever but it’s cloned to your local machine so no need to be connected actively
Harder to limit security on this type of source control

Question 3

How do you store large files in git?

Answer 3

Using LFS (large file storage). It stores a pointer to the real file
use ‘git lfs install’ to install it
then ‘git lfs track “*.mp4” ‘ to use it for all mp4 files

Question 4

Git command to add a new remote?

Answer 4

git remote add myNewRemote https://pathToMyNewRemote

Question 5

What are the 3 branching strategies?

Answer 5

GitFlow, GitHub Flow, and Release Flow

Question 6

What is Github Flow?

Answer 6

There’s 1 master branch always in a deployable state
You pull a new branch down when you start work on a feature

Question 7

What is GitFlow?

Answer 7

The most elaborate of the schemes
Have a master and a develop branch
Features are then branched off of develop
Features merge back to develop, then a release branch is made
When release branch is cleared, it’s merged back to master

Question 8

What is Release Flow?

Answer 8

There is a master branch
Features are branched off of here and then merged back to master
However master is never deployed
A new release branch is made for each deployment
This ensures theres a snapshot of each release

Question 9

What is branching by abstraction?

Answer 9

Essentially maintaining 2 copies of the code within the repo

Question 10

What are the types of merge commit?

Answer 10

Merge commit - just like a normal merge. You can see both sources
Squash commit - combine all individual comments from source and put it into one commit. Keeps log looking clean
Rebase - pushes your local changes out. Brings in newer changes from the master, then puts your changes back in

Question 11

What’s a monolithic repo?

Answer 11

All projects and apps in one repo
Pros: Easy code reuse, changes across apps can be done in one commit
Cons: very very large, plus tight coupling between apps

Question 12

What are some things you can secure with branch policies?

Answer 12

Set min # of reviewers
Limit merge types
Config build validation (and disallow merging if failed)
Call other API’s for validation

Question 13

What is Continuous Integration?

Answer 13

Integration of your changes with others changes, which when tested combined, still work.
Integration is ideally once per day
Works in conjunction with static analysis/unit testing

Question 14

What are the 4 pillars of CI?

Answer 14

Version Control
Package Management
CI system (Pipelines)
Automated Build

Question 15

What are examples of agentless pipeline tasks?

Answer 15

Waiting for manual approval
Inserting a delay
Calling a REST service

Question 16

What are pipeline variables and variable groups?

Answer 16

Variables store things like passwords, keys, or values
They can be locked and encrypted. Can link to Azure Key Vault
Use variable with syntax $(varName)
Variable groups are under the Pipeline / Library. They can’t be set a queue time. They can be shared across pipelines

Question 17

Pull requests and CI

Answer 17

You can have a CI build run every time a change or pull request is done. You can also deny the pull is the build fails
You can set an expiration for how long the clean build is valid

Question 18

What are YAML pipelines?

Answer 18

Pipelines run via a YAML config file
They don’t have to be connected to a source control task
Implicitly runs as one job
2 advantages: the file is stored with the codebase, available in every branch so it can be tailored to the branch

Question 19

What’s the basic structure of a YAML file?

Answer 19

Trigger - what starts the build
Steps - pieces to be run. Contains tasks and inputs
Can include jobs too. Jobs then contain steps
Order is ensured by using ‘dependsOn’ or condition logic

Question 20

What are agent pools?

Answer 20

built-in agent pools: managed by Microsoft, you can’t install extra stuff
private agent pools: defined by you on your own servers. You install the agent runtime. Allows for cost optimization, extra software and whitelisting

Question 21

Continuous deployment versus continuous delivery

Answer 21

Continuous deployment - artifacts are continuously validated and ready to be deployed
Continuous delivery - every version deployed passes all tests and deployed automatically

Question 22

What are deployment groups?

Answer 22

Every server the app will deploy to has an Agent installed on it. These boxes are then put in a deployment group. Tasks for this run on those machines, not on the devops agent

Question 23

What are blue-green deployments?

Answer 23

New version of the app deployed never deployed to live PROD
New version is deployed to a parallel PROD environment, then if it looks good, a proxy switches traffic to the new box

Question 24

What are immutable servers?

Answer 24

When a new version of the app is ready, a entirely new VM is brought up, and the old VM turned off. The old server is kept for a grace period, then destroyed

Question 25

What is progressive exposure?

Answer 25

Deployment strategy where users are slowly switched to the new code version over time

Question 26

What are canary deployments?

Answer 26

A progressive exposure tactic where only a small subset of users are sent to the new app version. If those users go well, the rest of users can be switched

Question 27

What are ring based deployments?

Answer 27

Multiple PROD environments exist and the servers are slowly switched to the new code version. Each server only serves part of the total user base, switching groups at a time. Used sometimes for global software

Question 28

What are feature flags?

Answer 28

A way to slowly expose new features.
The code has if/else logic and a database or setting file for which flags are on
Flags should be removed once the code is found to be working
Downside is there are more complex code paths, and more testing paths

Question 29

How to deploy mobile apps?

Answer 29

Use the VS App Center
You need an app definition for each OS you deploy to (iOS, Microsoft, Android)
You can use distribution groups to control test users
Can integrate with Pipelines for end to end traceability

Question 30

How to automate release notes?

Answer 30

Download Azure Release Notes Generator from GitHub
This will pull all work items and commits
Then generate a markdown file