Debug School: Nilasish Chakraborty

Git commands day 5

Nilasish Chakraborty — Fri, 18 Nov 2022 07:26:40 +0000

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: to merge the change between two remote branches
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 log --oneline: to check the history in oneline
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 user.name: we can configure the author name and etc. of the particular repo.

Day3 - How can we store container data in memory using docker volume

Nilasish Chakraborty — Wed, 16 Nov 2022 05:32:28 +0000

When we create a volume, it gets created in the local environment. When we run the container, the same file gets stored in the tmpfs and when the container is stopped, the tmpfs goes away and we can see the file in the local FS. So, In short, we can use the Docker's tmpfs feature to store container data in memory using docker volume.

Day2: Docker images

Nilasish Chakraborty — Tue, 15 Nov 2022 06:40:59 +0000

What is a Docker image. Explain in 10 points.

Docker image is a repository.
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
File systems are called layers as they are on top of each other in the docker images.
Each layer has a unique shad ID.
Docker image consists of multiple filesystems OR it is a collection of multiple filesystems.
Docker image has file system versioning.
For encrypting docker images, sha2-256bit algorithm is used.
All these layers merge to create one layer called mount.
Mount gets attached during runtime to the user.
If you change any file in a running container and stop it. The data will be stored at the diff directory. When the container will be restarted, then the file changes can be found intact.

Day-1 Docker Commands understand

Nilasish Chakraborty — Mon, 14 Nov 2022 09:50:00 +0000

what is the diff between docker pause and docker unpause
Hint - docker stats

----> Docker pause runs for only the running containers, not just the created ones whereas docker unpause only runs for paused containers not the stopped ones. If we run pause for a stopped container it's gonna give us a error message but not for a running container. Docker unpause will give the error message for a running or created container but not for a paused container.

What is the diff between docker stop and docker kill
Hints - Return value of linux + SIGNALs

---> Docker stop usually stops the container and keeps a message "Exited (0) n seconds ago" and Docker Kill gives the message "Exited (137) n seconds ago". That means Docker stop doesn't deallocate the memory the container is using but docker kill deallocates the memory from the container.

Docker Understanding

Nilasish Chakraborty — Mon, 14 Nov 2022 07:06:00 +0000

What is Docker?
--> It is a container management tool

Why Docker?
--> It gives us direct access to the System Kernel and create different environment for different applications.

What is Container?
--> Container is a running image which has it's own file system network and mount system.

Docker workflow?

Docker Resigtry(Hub) --> Docker Pull(image pull) + Docker Daemon talks to System Kernel + Docker Run (Creates container and runs the application)

How container created?
--> Docker Daemon talks to kernel and creates a isolated Linux/Windows Namespace system. Then it mounts the application code and Runs in an isolated environment by using the Host resources.