Debug School: Potukuchi Venkata Mahati

DevOps Training - GIT Questions - Assessment 1

Potukuchi Venkata Mahati — Fri, 18 Nov 2022 07:32:00 +0000

Write a Notes on Debug.school which must contains all the GIT commands which you learnt and one line explanation.
git init: to init or create a local repository
git clone: to clone the remote repository to local
git pull: to pull the changes remote repository to local(working dir)
git add: to move the file to the staging area
git commit: to commit the code to the local repository
git push: to push the code to the remote repository
git stash: to stash the local changes in a temporary folder
git stash pop: to pop the stashed changes
git merge: to merge the changes between two local repos
git fetch: git fetch is a primary command used to download contents from a remote repository
git pull: Git fetch + Git Merge
git cherrypick: to merge the particular change from feature to master branch or any branch
git rm: remove the change or unstage it from local repo
git tag: to tag the latest commit in a local branch
git tag -d : delete the tag
git mv : to move the file or changes between two folders in local repo
git diff : to check the difference between two commits, two commit id need to be passed as arguments
git log: to check the history of commit for a specific branch
git revert: to revert the latest changes or commits from local branch
git status: to check the status of the particular change or file
git config : To set the configuration for your git repo like username , Email

DevOps Training - Docker Questions - Assessment 6 : Day 3

Potukuchi Venkata Mahati — Wed, 16 Nov 2022 05:15:00 +0000

How can we store container data in memory using docker volume?
We can use the tempfs as mount type.
This is a type of filesystem which is stored in container's memory, so this is temporary storage, when we stop the container, the data written to this tmpfs will be lost.
This is the fastest way to access memory.
It can be used to process the runtime data like some queue in storage, some mathematical formulas, etc.
We can not attach this volume with some other container because we don't know the Physical location in this case.

Below is the command for attaching tmpfs to container -

docker run -itd --name --mount type=tmpfs,destination=/opt/example ubuntu

DevOps Training - Docker Questions - Assessment 4 : Day 2

Potukuchi Venkata Mahati — Tue, 15 Nov 2022 06:28:00 +0000

What is a Docker image. Explain in 10 points.

Docker image is a repository.
It is just a name for human beings to remember instead of numbers.
100s of base docker images are stored in hub.docker.com called registry.
Docker image consists of multiple filesystems -- ROOTFS + USERFS + ... //This both together are called base image
Docker image consists of multiple filesystems OR it is a collection of multiple filesystems.
Docker image has file system versioning.
File systems are called layers as they are on top of each other in the docker images.
Each layer has a unique shad ID.
All these layers merge to create one layer called mount.
Mount gets attached during runtime to the user.
Changes made like writing file, updating file, etc. are updated in both merged layer and image layer.
For encrypting docker images, sha2-256bit algorithm is used.

DevOps Training - Docker Questions - Assessment 3 : Day 2

Potukuchi Venkata Mahati — Tue, 15 Nov 2022 04:55:00 +0000

1. What is the use of "docker update"? Hint - docker run --help
Docker Update is used for configuring one or more containers during runtime to modify the resources like number of CPU, memory limit, PID limit dynamically to avoid limiting the usage of resources on the host machine.

2. What is the use of "docker wait"?
Docker wait command is used to wait until one or more containers stop for continuing with the next action.

DevOps Training - Docker Questions - Assessment 2

Potukuchi Venkata Mahati — Mon, 14 Nov 2022 09:49:58 +0000

1. What is the difference between docker pause and docker unpause? (Hint - docker stats)
The docker pause command suspends all processes in the specified container whereas the docker unpause command resumes all processes in the specified container.

2. What is the difference between docker stop and docker kill (Hints - Return value of linux + SIGNALs)
Below are the differences -
a) docker stop attempts to gracefully shutdown the container whereas docker kill stops/terminates the container immediately.
b) docker stop returns None as return value whereas docker kill returns 0 (true) if the process was killed or1 (false) if the kill failed.
c) docker stop sends a SIGTERM signal to the main process inside the container whereas docker kill sends a SIGKILL signal.

DevOps Training - Docker Questions - Assessment 1

Potukuchi Venkata Mahati — Mon, 14 Nov 2022 07:15:00 +0000

1. What is Docker?
Docker is a Container Management Tool which helps to build, deploy, run, update and manage containers.
2. Why Docker?
Docker is used in order to mainly save time and resources. To avoid the havoc of multiple resource creation and management.
3. What is Container
A container is a runnable instance of a docker image which can be used to run applications.
4. Docker workflow
Docker Daemon -> Docker CLI -> Docker Engine API
Docker Host -> Docker Client -> Docker Registry (Hub)
5. How container created?
Source Docker Image -> Run the image -> make it active
The docker daemon requests the kernel for creating a Linux namespace with a mount, an isolated network and the runtime environment.