This article contains information about what docker is and how to install and use it.<\/p>\n
It is a program that allows the creation of containers to sharing the resources of the operating system efficiently.<\/p>\n
The Container is basically a structure that allows the efficient use of operating system resources.<\/p>\n
Processors and ram in computers are not always fully utilized by the operating system.<\/p>\n
Since resources are not fully used, computer resources are divided so that they can be used efficiently by different programs.<\/p>\n
For this purpose, various virtualization software such as VMWare and Virtualbox are used.<\/p>\n
Virtualization software needs to install new operating system while sharing resources.<\/p>\n
A new operating system may cause unnecessary use of resources that applications do not need.<\/p>\n
For example; An application used to store user information may not use screen resources.<\/p>\n
However, since operating system programs require a video card, video card resources that are not required for the application are also used.<\/p>\n
The new operating system for virtualization must be rebooted and installed.<\/p>\n
In the container structure, the resources needed by the application are shared softwareatically and unnecessary resource usage resulting from virtualization is prevented.<\/p>\n
Because the existing operating system resources are divided in the container structure, applications can be run quickly.<\/p>\n
In addition, the working environment required for the application can be prepared with the image in the container structure to ensure that the application is portable.<\/p>\n
The files required for installation are downloaded from docker.com and installed according to the operating system. Installation is done like an application installation on the operating system.<\/p>\n
The installation is checked by typing the following commands into the operating system command prompt(CMD, Powershell, Bash, etc.).<\/p>\n
docker version<\/pre>\nThe following command is used for detailed information about image, container and container count in the system.<\/p>\n
docker info<\/pre>\nCreate Container From Image<\/h3>\n
The following command can be used for sample container usage.<\/p>\n
docker run hello-world<\/pre>\nThe command will create a container using the hello-world image. Before using Docker, it is useful to know how Docker works. Docker needs files called images to create containers.<\/p>\n
What is Docker Image?<\/h4>\n
The image basically contains the files and settings that will be executed when the container is started or after it is started.<\/p>\n
Docker creates and runs containers using the commands in the image. In the example of hello-world above, first the hello-world image is searched on the computer, if it is not found, it is downloaded from “hub.docker.com” and a container is created.<\/p>\n
Once the container is created, the commands are executed using the Dockerfile settings in the image. A new image can be created when working with Docker. However, it will be useful to use the images at hub.docker.com before creating an image.<\/p>\n
Search Docker Images in hub.docker.com<\/h3>\n
The search command is used to search for images.<\/p>\n
docker search hello-world<\/pre>\nDownload Docker Images<\/h3>\n
The pull command is used to download images.<\/p>\n
docker pull hello-world<\/pre>\nList Docker Images<\/h3>\n
The images command is used to list images.<\/p>\n
docker images<\/pre>\nDelete Docker Images<\/h3>\n
The rmi command is used to delete the image.<\/p>\n
docker rmi hello-world<\/pre>\nDocker Image History<\/h3>\n
The history command is used for image history.<\/p>\n
docker history hello-world<\/pre>\nRun Docker Images<\/h3>\n
The run command is used to run the image.<\/p>\n
docker run hello-world<\/pre>\nNOTE:<\/strong> Images not listed are downloaded from hub.docker.com.<\/p>\n
There are different uses of image running according to the image content.<\/p>\n
The -name parameter is used to run the image with a custom name.<\/p>\n
docker run --name my-image hello-world<\/pre>\nThe -it parameter is used to run the image interactively.<\/p>\n
docker run -it centos \/bin\/bash<\/pre>\nThe -d parameter is used to run the image in the background.<\/p>\n
docker run -d hello-world<\/pre>\nThe -p parameter is used to export the image port.<\/p>\n
docker run -it -p 1453:80 nginx<\/pre>\nFrom the browser, enter localhost:1453.<\/p>\n
NOTE:<\/strong> We have accessed port 80 that the image uses, through the 1453.<\/p>\n
In order for the application or other files to be used by the image, it must be passed to the image with the volume property.<\/p>\n
The -v parameter is used to passing files to image.<\/p>\n
docker run -v \"File-directory-path\":\/usr\/share\/nginx\/html:ro -it -p 1453:80 nginx<\/pre>\nVarious operating system commands can be used to pass the current directory to image.<\/p>\n
docker run -v %cd%:\/usr\/share\/nginx\/html:ro -it -p 1453:80 nginx<\/pre>\ndocker run -v $(pwd):\/usr\/share\/nginx\/html:ro -it -p 1453:80 nginx<\/pre>\nNOTE:<\/strong> The directory path indication differs depending on the operating system.<\/p>\n
List Running Containers<\/h3>\n
The ps command is used to list the running containers.<\/p>\n
docker ps<\/pre>\nList All Containers<\/h3>\n
The ps -a command is used to list the running containers.<\/p>\n
docker ps -a<\/pre>\nThe top command is used for container operations.<\/p>\n
docker top container-id<\/pre>\nDifference between docker kill and stop<\/h3>\n
You can learn the difference between stop and kill commad below.<\/p>\n
Stop Running Container<\/h3>\n
The stop command is used to stop the running container.<\/p>\n
docker stop container-id<\/pre>\nForce Stop Running Container<\/h3>\n
The kill command is used to force stop the running container.<\/p>\n
docker kill container-id<\/pre>\nStart Stopped Container<\/h3>\n
The start command is used to run the stopped container.<\/p>\n
docker start container-id<\/pre>\nWhich Docker command lets us attach to a running container?<\/h3>\n
The attach command is used to make the running container interactive.<\/p>\n
docker attach container-id<\/pre>\nRun Container Interactively<\/h3>\n
The ai parameter is used to interactively run the stopped container.<\/p>\n
docker start -ai container-id<\/pre>\nGet Information About Docker Container<\/h3>\n
The inspect command is used to get information about the container.<\/p>\n
docker inspect container-id<\/pre>\nCheck Docker Resource Usage<\/h3>\n
The stats command is used for resource usage information of the running container.<\/p>\n
docker stats container-id<\/pre>\nDocker Log Information<\/h3>\n
The logs command is used for the log information of the container.<\/p>\n
docker logs container-id<\/pre>\nRemove Docker Container<\/h3>\n
The rm command is used to remove docker container.<\/p>\n
docker rm container-id<\/pre>\nThe –rm parameter is used to automatically delete the container after completing its operation.<\/p>\n
docker run --rm hello-world<\/pre>\nRemove All Docker Containers<\/h3>\n
The below commands can be used to remove all docker containers.<\/p>\n
docker rm $(docker ps -aq)<\/pre>\ndocker sytem prune<\/pre>\nNOTE:<\/strong> To remove the running container, it must first be stopped.<\/p>\n
NOTE:<\/strong> There are multiple commands in the Docker that perform an operation.<\/p>\n
Dockerfile<\/h2>\n
What is a Dockerfile?<\/h3>\n
The Dockerfile file is used to create a custom image. The file contains various instructions on how to create a container.<\/p>\n
FROM-> Refers to the image to be used.
\nLABEL-> Refers to the image label.
\nRUN-> Refers to the commands to be executed. (used for required installations.)
\nCMD-> Refers to the commands to be executed. (Used for commands to be executed after necessary installations are made.)
\nENTRYPOINT-> Refers to the path of the commands to be executed.
\nCOPY-> Specifies the files to be copied to the image.
\nWORKDIR-> Refers to the working directory.
\nENV-> Refers to theenvironment variables.
\nEXPOSE-> Refers to the image port number.
\nVOLUME-> Refers to the files to be passed to the image.<\/p>\nThe build command is used to create images with Dockerfile.<\/p>\n
docker build -t image-name:version -f Dockerfile-File<\/pre>\nIf the dockerfile is in the same folder, just use a dot(.).<\/p>\n
docker build -t image-name:version .<\/pre>\nCreate a Dockerfile<\/h3>\n
Create the following file as Dockerfile.<\/p>\n
FROM centos\nLABEL Vendor=\"SEZER\" License=MIT Version=0.1\n\nCMD [\"echo\", \"Image created.\"]<\/pre>\nCreate the image with the command below.<\/p>\n
docker build -t image:0.1 .<\/pre>\nList images;<\/p>\n
docker images<\/pre>\nRun the images by taking the ID of the image.<\/p>\n
docker run image-id<\/pre>\nYou will see “Image created.” on the screen. Similarly, you can create images according to your wishes. Here is an example Dockerfile file that runs Java commands.<\/p>\n
FROM java:8\nCOPY . \/var\/www\/java\nWORKDIR \/var\/www\/java\nRUN javac file.java\nCMD [\"java\", \"file\"]<\/pre>\nNOTE:<\/strong> You can create images according to your need by using the instructions above.<\/p>\n
Docker Compose<\/h2>\n
What is a docker compose?<\/h3>\n
An application developed can use multiple services.<\/p>\n
For example, an application developed using a programming language such as Node.js, PHP, C # or Java may require a database such as MySQL, SQL Server, or MongoDB.<\/p>\n
According to the application, services such as “log, http server” can be used.<\/p>\n
In this case, instead of gathering all the services under one image, it would be beneficial to use all the services under a different image.<\/p>\n
It will be difficult to create and manage each image separately.<\/p>\n
The application running in one image may depend on the image contained within another image.<\/p>\n
In this case, multiple images can be managed with Docker compose.<\/p>\n
Docker compose stores the settings in the docker-compose.yml file.<\/p>\n
version: \"3\"\n\nservices:\n mysql:\n image: mysql\n ports: \n - \"3306:3306\"\n environment:\n MYSQL_DATABASE: database\n MYSQL_USER: user_name\n MYSQL_PASSWORD: user_password\n MYSQL_ROOT_PASSWORD: root_password\n php:\n build: \n context: .\/php\/\n ports: \n - \"8001:80\"\n volumes:\n - .\/www:\/var\/www\/html\/\n depends_on:\n - mysql<\/pre>\nIn the example above, mysql service port and environment variables are set.<\/p>\n
In php service;<\/p>\n
The Dockerfile file in the php folder was used.<\/p>\n
With volumes, the files to be used are determined.<\/p>\n
With depends_on, the image to which the image is depended is determined.<\/p>\n
As these settings will vary according to the structure to be used, it will be useful to prepare the appropriate structure according to the need.
\nHave a good day.<\/p>\n<\/div>\n