sai durga devi – Best DevOps

List of 20 docker commands and its use cases with example ?

sai durga devi — Tue, 30 Aug 2022 08:01:35 +0000

-> docker –version
This command is used to get the currently installed version of docker
-> docker pull
This command is used to pull images from the docker repository
-> docker run
This command is used to create a container from an image
-> docker ps
This command is used to list the running containers
-> docker ps -a
This command is used to show all the running and exited containers
-> docker exec
This command is used to access the running container
-> docker stop
This command stops a running container
-> docker kill
This command kills the container by stopping its execution immediately
-> docker commit
This command creates a new image of an edited container on the local system
-> docker login
This command is used to login to the docker hub repository
-> docker push
This command is used to push an image to the docker hub repository
-> docker images
This command lists all the locally stored docker images
-> docker rm
This command is used to delete a stopped container
-> docker rmi
This command is used to delete an image from local storage
-> docker build
This command is used to build an image from a specified docker file
-> docker-compose restart
You want to restart a container with the service name or container name.
-> docker-compose logs
the service crashed on launch and you want to know why
-> docker-compose stop
You want to stop your container by service name or container name.

What is the difference between CMD vs Entry point ?

sai durga devi — Tue, 30 Aug 2022 08:00:35 +0000

The ENTRYPOINT instruction looks almost similar to the CMD instruction. However, the main highlighting difference between them is that it will not ignore any of the parameters that you have specified in the Docker run command (CLI parameters).
-> CMD : Sets default parameters that can be overridden from the Docker Command Line Interface (CLI) when a container is running.
-> ENTRYPOINT : Default parameters that cannot be overridden when Docker Containers run with CLI parameters.

List of dockerfile instructions and its Brief Summary?

sai durga devi — Tue, 30 Aug 2022 07:59:33 +0000

There are multiple INSTRUCTIONS that are available in Dockerfile, some of these include:

From :The FROM instruction specifies the Base Image from which you are building.
RUN: In this we can run our commands for installing the packages
ADD: This instruction will give the output of converting tar file in to normal file and it will add in to that particular directory.
COPY: This instruction will give the output of copying the content and nothing will do more than that in the docker instruction. This instruction will give you the result of moving files.
EXPOSE: The EXPOSE instruction informs Docker that the container listens on the specified network ports at runtime.
WORKDIR: The WORKDIR instruction sets the working directory for any RUN, CMD, ENTRYPOINT, COPY and ADD instructions that follow it in the Dockerfile.The WORKDIR instruction can be used multiple times in a Dockerfile.

What is the differenet between docker exec and attach?

sai durga devi — Tue, 30 Aug 2022 07:58:08 +0000

-> Attach:This command to attach your terminal’s standard input, output, and error to a running container using the container’s ID or name.
-> exec: The docker exec command runs a new command in a running container. execute the below command after restarting the container node API

What is the difference between docker stop and kill?

sai durga devi — Tue, 30 Aug 2022 07:56:27 +0000

Starting and stopping a container is not the same as starting and stopping a normal process. To terminate a container, Docker provides the docker stop and docker kill commands. Both the docker kill and docker stop commands look similar, but their internal execution is different. The docker stop commands issue the SIGTERM signal, whereas the docker kill commands sends the SIGKILL signal. The execution of the SIGTERM and SIGKILL. is different. Unlike SIGKILL, the SIGTERM gracefully terminates a process rather than killing it immediately. It is possible to handle, ignore or block a SIGTERM signal, but a SIGKILL signal cannot be blocked or handled. SIGTERM allows a child process or parent process the opportunity to send information to other processes

What is the differenet between docker pause and unpause?

sai durga devi — Tue, 30 Aug 2022 07:55:05 +0000

-> Docker Pause :
It will suspend all processes in the specified containers. It means that the processes in the container stop running, and they can resume later.
-> Docker Un pause :
It will resume all the processes in the specified container. It means recovery container all processes.

Components of Docker and its Brief Summary ?

sai durga devi — Tue, 30 Aug 2022 07:52:45 +0000

the docker is virtualization operating system which is mainly used for development and running application through containers which are lightweight software blocks can run application with all dependencies.
-> Components of docker :
1)Docker client: Whenever we are using docker commands, the client sends the commands to dockerd, which carries them out. The docker command uses the Docker API. Then the docker can communicate with more than one daemon.

2)Docker image: Docker Image is a file that contains all the necessary dependency and configurations which are required to run an application: code, runtime, system tools, system libraries and settings.

3)Docker Daemon : It will listens the docker API requests and manages docker objects such as images, containers, networks, and volumes. A daemon can also communicate with other daemons to manage Docker services.

4)Docker Networking: Docker takes care of the networking aspects so that containers can communicate with other containers and also with the Docker Host. Docker networking subsystem is pluggable, using drivers. There are several drivers available by default and provides core networking functionality.

5)Docker registry: A Docker registry stores Docker images. Docker Hub is a public registry that anyone can use, and Docker is configured to look for images on Docker Hub by default. You can even run your own private registry.

6)Docker Compose: Sometimes you want to run multiple containers but as a single service. This task can be accomplished with the help of Docker compose as it is specifically designed for this goal. It follows the principle of isolation between the containers but also lets the containers interact with each other. The Docker compose environments are also written using YAML.

7)Docker swarm: Docker Swarm is a container orchestration tool that is natively supported by Docker. A node is an instance of the Docker engine participating in the swarm. To deploy your application to a swarm, you submit a service definition to a manager node. The manager node dispatches units of work called tasks to worker nodes.