VineeshP – Best DevOps

What is Pod in kubernetes. Exaplin in 15 points with image as an example

VineeshP — Wed, 01 Sep 2021 07:00:35 +0000

Atomic Unit of kubernetes
Pod contains one or more containers
A node can have multiple pods
pods have few states – pending, running, succeeded/failed
pods are ephemeral

What are the components of Kubernetes worker and explain each component’s function?

VineeshP — Wed, 01 Sep 2021 06:56:13 +0000

docker – which builds and run the container.
kubelet – A service for communication with etcd etc.
kube-proxy – it is resposible for managing network. it makes the ports available to external.

What are the components of Kubernetes master and explain each component’s function?

VineeshP — Wed, 01 Sep 2021 06:52:17 +0000

etcd – It is the storage. it is key value pair.
apiserver – It is the listener
scheduler – it schedules, mean add new pods if necessary.
controller manager – it monitors the pods always.

Write down 10 features of Kubernetes with image

VineeshP — Wed, 01 Sep 2021 06:43:27 +0000

Monitoring the pods
Add or Remove pods if necessary.
Extensibility
Scalability
Failure discovery and handling
Ip address allocation for pods

List out number of storage/volume drivers supported by docker?

VineeshP — Tue, 31 Aug 2021 09:43:25 +0000

overlay2
fuse-overlayfs
btrfs
zfs
vfs
aufs
devicemapper
overlay

Q1. List out all INSTRUCTION statement of dockerfile and give one line explanation.

VineeshP — Tue, 31 Aug 2021 07:07:27 +0000

FROM -It should be the first instruction in the Dockerfile. It is used to specify our base layer from which we are creating the image.
MAINTAINER – It is used to set the author.
RUN – It is used to run a command in shell.
CMD – It provides a default executable for a container.
LABEL – It is used for putting some metadata in a container.
EXPOSE – Expose a port and listens to it.
ENV – Used to set the environment variables.
ADD – Add new files and directories to filesystem.
COPY – Copies files and directories from src to dest.
ENTRYPOINT – Allows you to configure a container that will run as an executable.
VOLUME – Creates a mount point.

Create one Image which have base as centos and with git – ntp – httpd.

VineeshP — Tue, 31 Aug 2021 05:39:12 +0000

docker run –name vin_centos -itd centos:latest
docker ps
docker attach 083fb828fcad

docker ps
docker commit -a”Vineesh” -m”Updated Centos” 083fb828fcad vineesh_centos2
docker images
docker run –name Vineesh_Centos2 -itd 32083f4af9be
docker ps
docker exec a9c938de7bdb git

Create one Image which have base as ubuntu and with git – ntp – apache2.

VineeshP — Tue, 31 Aug 2021 05:26:27 +0000

docker run –name vin1 -itd ubuntu:latest
docker ps
docker attach e80fd4a69088
docker commit –help
docker commit -a”VIneesh” -m”Added apache” e80fd4a69088 vineesh_ubuntu
docker images
docker ps
docker exec e80fd4a69088 git
docker images
docker run -itd vineesh_ubuntu
docker ps
docker exec acdda25da2d2 git

What is Docker Images and Exaplin in 10 bullet lines?

VineeshP — Tue, 31 Aug 2021 05:06:55 +0000

Images are the base of a container.
Images are like classes and containers are like objects.
We can create any number of containers from an image.
Images can be created from Dockerfile or we can pull from registry.
Images can have multiple layers.
Images have root file systems , PID, USER namespace etc.
Image layers are named with SHA256 algorithm.

What is Storage Driver and types of Storage Driver? Explained with Images.

VineeshP — Tue, 31 Aug 2021 05:00:17 +0000

Storage drivers are used to write to the container’s writable layer. overlay2 is the most commonly used storage driver nowadays. overlay2 is the default storage driver.

Q2. – What is the use of “docker wait” commands? with example and image

VineeshP — Tue, 31 Aug 2021 03:25:01 +0000

This command is used for waiting one or more containers to stop. We have to open 2 terminals. In one of them just put docker wait and in the other try to stop the same container. We can see the first terminal with docker wait is returned 0 and stopped waiting.

docker wait renamed1 [Terminal1]

docker stop renamed1 [Terminal2]

Q1. – What is the use of “docker update” commands? with example and image

VineeshP — Tue, 31 Aug 2021 03:24:34 +0000

It is used for updating container’s configuration. A container have different configurations. We can change those configurations via docker update command.

docker update –restart=on-failure:3 renamed1

In the above example we are changing the restart policy of a container.

Assignment for docker day1

VineeshP — Mon, 30 Aug 2021 08:39:15 +0000

Q1. Explain What is Docker Container with image?

A container which contains our image with root file system, 1 PID, 1 NW, 1 MNT, 1 USER.

Q2. What is the difference between docker stop and docker kill?

docker stop and docker kill doing the same thing only the internal process have difference. Both stops a running container to an exit state.

docker create –name vin6 httpd
docker start vin6
docker ps
docker stop vin6
docker ps -a
docker start vin6
docker pause vin6
docker ps -a
docker unpause vin6
docker images -a
docker ps -a
docker stop vin6
docker restart vin6
docker ps
docker kill vin6

Q3. What is the differenece between docker pause and docker unpause?

Docker pause is used to pause the running container which can be resumed with unpause. But is we stop or kill we can not unpause but we can restart.

Q1. Explain What is Docker Container with image?

VineeshP — Mon, 30 Aug 2021 07:34:49 +0000

A container which contains our image with root file system, 1 PID, 1 NW, 1 USER.

Q3. What is the differenece between docker pause and docker unpause?

VineeshP — Mon, 30 Aug 2021 07:27:53 +0000

Docker pause is used to pause the running container which can be resumed with unpause. But is we stop or kill we can not unpause but we can restart.

Q2. What is the difference between docker stop and docker kill?

VineeshP — Mon, 30 Aug 2021 07:26:14 +0000

docker stop and docker kill doing the same thing only the internal process have difference. Both stops a running container to an exit state.