Debug School: V JAGADEESH CHARY

devops day-2 assignment

V JAGADEESH CHARY — Fri, 28 Apr 2023 06:50:47 +0000

Docker commands:
Port - to interact with container from internet
ps - to list docker container details
logs - go get the logs from container (PID1)
stats - get the computation power details of container
top - to get the running processes details of container
events - to get the events logs from dockerd ( through events terminal)
update - to Update configuration of one or more containers (CPU and Memory)
wait - this holds the container process(like kill) till execute pipeline process of other container

Image : collection of file systems(root(user),app)

- docker gives unique name to each file system and will be downloaded to overlay2 folder
- we can call each file systems as layer , top layer will be root file system layer
- each layer will have parent layer and one parentless (root layer)
- all the layers are merged as one layer and mounted to container
- merged layer will be divided into two parts (diff, merge)
- merge - get attached to mount
- diff - changed to container files(merge) will be added to diff
- if comment happens, new layer will be created from diff (read only) and its called new image (get-docker.sh)
- changes to the container (adding, deleting, modifying) in the merge will be added to diff location
- if new image from existing image ,it will be created from diff layer part as read only mode(new layer with combined old layers)
- Image creation can be implemented in two ways
-- all required layers in one layer(command)
-- each layer in each command (best practice)
- To share image locally (with same network) create tarball and can be shared name (save .tar and load commands)
- In order to share the create images with others ,will be uploaded in to repository (public,verivate)
- Most popular image repo is docker hub
- Login into docker hub through command line and by using tag ,can upload images to docker hub

Kubernetes questions day 3

V JAGADEESH CHARY — Wed, 26 Apr 2023 09:58:13 +0000

what is Kubernetes

Kubernetes is orchestration tool to manage the containers.

why Kubernetes

Kubernetes is used for deploying and managing containerized applications.

Explained Kubernetes Architecture

It containers below components
- API server: To process requests from client
- etcd : storage unit with all API data with key value pair
- control manager: to control total process of orchestration. The API server is the front end for the Kubernetes control plane.
- scheduler: to schedule pods/containers. component that watches for newly created Pods with no assigned node and selects a node for them to run.

Master components

API server, ETCD, Control manager, Scheduler

worker components

kubelet, container engine

workstation components

kubelet with json or yaml

what is pod

basic logical unit of Kubernetes scheduler

Day 1 Docker - Assignment

V JAGADEESH CHARY — Mon, 24 Apr 2023 19:15:17 +0000

What is Docker?

Docker is container management tool

Why We need docker?

To save time (number of applications can run at a time)- To save cost (CPU, less RAM ,storage,operational cost will be less) - Improve software quality (quality coding,quality testing)

What is Container?

Container is lightweight (minimal resources) application runtime environment without kernel
Container is resources created by namespaces and together powered by kernel

How Container Works?

docker will request kernel to create independent computational resources like network,PID,mount and username, those all resources combined and creates a runtime environment.
- When client request for docker image (if not available local,will be fetched from repo) and kernel will create user and will be assigned to computational resources like network,PID,mount and username

How to install Docker?

Docker provides convenience scripts at get.docker.com.
Step 1 – Download and Run the script.
$ curl -fsSL get.docker.com -o get-docker.sh
$ sudo sh get-docker.sh
Step 2 – Enable Docker
$ sudo systemctl enable docker
Step 3 – Start Docker
$ sudo systemctl start docker
Step 4 – Verify that docker is installed correctly by running the hello-world image.
$ sudo docker run hello-world

What are the components docker?

docker engine,docker images,registry,container

What is a container lifecycle commands?

create,start,stop,restart,pause,unpause,kill,remove

What is docker pause/unpause?

docker pause: Memory will be used but CPU allocations will be paused (no access to container)
docker unpause: Memory will be used but CPU allocations will be re allocated ( access to container)
this commands works with respect to accessing the resources

What is docker stop/kill?

docker stop : graceful stopping (first child process will be killed, later parent process will be killed)
docker kill : forcefully kills the container ( Directly parent process will be killed )

How to get inside a container?

by using shell

How to access container from outside?

by using network

What is the rule for container is running?

PID1 has to run with anything (because no kernel in the container) which should not be excited.