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A docker is a type of platform that allows its users to deliver any applications successfully on the cloud. A docker carries no dependencies. A docker-compose is a platform that helps carry out all the docker processes successfully. The key difference between Docker and docker-compose is that Docker works on command-based; however, docker-compose works on YAML file configuration. In this article, we will talk more about Docker as well as docker-compose, their benefits, and some basic commands for both.
A Docker is a virtualized platform in the operating system allowing all the technical organisations to easily design, create, deploy, as well as run the applications present in the Docker containers. It performs everything having all the dependencies present in them. The docker container is considered to be a very lightweight package that contains a lot of dependencies and instructions within it, like libraries, frameworks, and bins.
The concept of Docker is increasing and gaining a lot of popularity with time as this concept has totally changed the development process of the software. A docker can be used during multiple phases of languages, but it is most commonly used during the deployment phase.
The working of a docker depends on a docker engine that consists of a server and a client. The process of communication between them is conducted with the help of Rest API. In this process, the message is sent to the server via the client in the form of instructions.
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Docker-compose is a platform that helps in carrying out all the docker processes successfully. It is commonly used for running multiple docker containers in the form of a single service. For instance, let's assume a user has an application that requires MySQL and NGNIX. The idea he could consult is he can simply create a file to start both the containers running as a service without needing to start any of them individually.
All the docker-compose files are, by default, YAML files. They can be created using vim editor.
Purpose: The main purpose of a docker file is image creation, whereas the main purpose of a docker-compose is to run a container in the form of a single service.
File Type: A docker does not need any extension; hence the file type is extensionless, whereas, for docker-compose, the extension used is a command.yaml.
Reciprocity: IT is not possible for a docker file to call docker-compose; however, a docker-compose can invoke the docker file.
Command: The associated command with Docker is Docker build; however, docker-compose up is the associated command for docker-compose.
Service: A docker provides its users with the service to call for assembling an image, whereas a docker-compose helps in defining the services that help in designing the app using docker-compose.yaml and then makes them run in an isolated environment.
Containers: A docker cannot handle more than one container; however, a docker-compose can hold multiple containers.
Design: A docker helps the user to update an already existing image, whereas a docker-compose works best in designing the latest version of the image using a docker-compose command. Hence we can say that a docker builds the images whereas docker-compose runs the image.
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Below are a few docker commands that users should be aware of while working with docker.
Docker-version: This docker command helps in getting the latest installed version of the docker. Lets us see how the command works:
HKRTraining@Manager -1:~$ docker - -version
Docker version 17.05.0-ce, build 89658be
HKRTraining@Manager-1:~$
Docker pull: This docker command helps in pulling images from the docker repository mainly available on hub.docker.com. Lets us see how the command works: docker pull
HKRTraining@Manager -1:~$ docker pull ubuntu
Using default tag: latest
latest: pulling from library/ubuntu
Ae79f2514705: Pull complete
C59d01a7e4ca: Pull complete
41ba73a9054d: Pull complete
F1bbfd495cc1: Pull complete
0c346f7223e2: Pull complete
Digest: bfouhwnpowjpefokgepkge
Status: Downloaded newer image from ubuntu: latest
HKRTraining@Manager -1:~$
Docker run: This docker command helps in creating a container for the image of the docker. Lets us see how the command works: docker run -it -d
HKRTraining@Manager -1:~$ docker run -it -d ubuntu
nwfoqfkmqpof3kg3pogpo4m4pog
HKRTraining@Manager -1:~$
Docker ps: This command helps in listing the already running containers in the docker. Lets us see how the command works:
HKRTraining@Manager -1:~$ docker ps
CONTAINER ID IMAGE COMMAND CREATED STATUS
PORTS NAME
HKRTraining@Manager -1:~$
Docker ps -a: This command helps in listing the already running containers in docker including all the existing containers. Lets us see how the command works:
HKRTraining@Manager -1:~$ docker ps
CONTAINER ID IMAGE COMMAND CREATED STATUS
PORTS NAME
(0) 21 seconds ago
HKRTraining@Manager -1:~$
Docker exec:This command helps in accessing the running container. Lets us see how the command works: docker exec -it
HKRTraining@Manager -1:~$ docker exec -it nqwnfnf bash
root@nqwnfnf :/#
Docker stop: This command helps in stopping a running container in the docker. Lets us see how the command works: docker stop
HKRTraining@Manager -1:~$ stop nqwnfnf
nqwnfnf
HKRTraining@Manager -1:~$
Docker kill: This command helps in stopping a running container’s execution in the docker immediately. The main difference between the docker kill command and the docker stop command is that the docker stop command does not stop the container immediately. It allows the container some time to shut down. Lets us see how the command works: docker kill
HKRTraining@Manager -1:~$ kill nqwnfnf
nqwnfnf
HKRTraining@Manager -1:~$
Docker commit: This command helps in creating a new image of the container present in the local system. Lets us see how the command works: docker commit
HKRTraining@Manager -1:~$ docker commit nqwnfnf hshar ubuntunew
Sha256: nggnpgj3pgopo4kp4oktpowhfnm
HKRTraining@Manager -1:~$
Docker-compose - -help: This command shows help for the instructions and arguments.
Docker-compose builds: This command looks for all services that contain the statement in the docker-compose .yaml file and then run the Docker.
Docker-compose run: This command runs a single-time command for a service.
Docker-compose up: This command helps in building, recreating, starting as well as attaching containers to a service.
Docker-compose -f: This command helps in specifying the location of the docker-compose simply by adding -f flag.
Docker-compose start: This command helps in starting the existing container for service.
Docker-compose stop: This command helps in stopping the running container in service without removing them.
Docker-compose pause: This command helps in pausing the existing container in service.
Docker-compose unpause: This command helps in unpausing the already paused container in service.
Docker-compose down: This command helps in stopping the running container in service, removing all the containers, volumes, and images.
Docker-compose ls: This command helps in listing the running compose projects.
Top 30 frequently asked Docker Interview Questions !
A few advantages of using Docker are listed below:
Portability: It is possible for a user to port an application created with Docker on another platform where Docker is running. The new platform will let the docker application perform in the exact same manner as the old platform.
Performance: Containers are believed to contain very small blueprints as they do not contain any operating system, unlike virtual machines. Hence docker containers are faster and quicker.
Agility: The development process with the Docker is very responsible and agile.
Isolation: A container present in the Docker has one of the user's applications. Not just this, but the container also consists of a few relevant versions of the supporting software affiliated with the application requirement. If, in case, there is another docker that contains the applications requiring different versions of the same software, then this is not a problem as all the docker containers are independent of each other.
Scalability: It is possible to create new docker containers instantly as per the demand of the application. There are several management options also that a user can take advantage of.
Standardisation: Docker helps in creating a standard environment for the user as consistency is maintained all over the cycle creation as well as deployment.
Fast Configuration: It is very easy and simple to configure and modify application services in docker-compose. This happens because of YAML scripts.
Secure communication: The internal communication between the multiple containers of the Docker is very easy and secure using the docker-compose. It creates a safe network for all the existing services for the exchange as the services are not externally accessible.
Portability: As all the services take place inside the docker-compose, hence it is easy for the developers to access as well as share the complete configuration. It is done by launching the environment within minutes using the YAML file and its source code. This makes it easier to set up and enable a productive CI/CD pipeline.
Efficient Resources Use: It is possible with docker-compose to host multiple environments on a single host. Docker-compose can run everything on a single hardware and helps the user in saving lots of resources. Hence, this helps in using the resources efficiently.
Preserving Volumen data: It is a great benefit of using docker-compose as it saves data utilised by the services. Hence, a user gets stress-free about the loss of data in the docker containers.
Conclusion:
In this article, we have discussed Docker and docker-compose along with the benefits of both and the main differences between them. We can conclude by saying that a docker is a type of platform that allows its users to deliver any applications successfully on the cloud, whereas a docker-compose is a platform that helps in carrying out all the docker processes successfully. We have also discussed the basic commands affiliated with both Docker and docker-compose.
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Yes, you need a docker for a docker-compose
Yes, a docker has a docker container containing everything that is required to run an application.
A docker file consists of all the coker commands used for assembling an image.
A docker-compose file is basically a YAML file saved with .yaml extension. The default path for finding this is ./docker-compose.
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