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Articles by Hemant Sharma
34 articles
How to pass command line arguments to a python Docker container?
Before getting into the docker container arguments we must know about python command line arguments and how they are accessed by the developer. Command line arguments are of great use when we want our python script to be controlled outside of the program. Access the python script’s command line arguments Step 1: Create a python script main.py Example # sys will allow us to access the passed arguments import sys # sys.argv[0] access the first argument passed that is the python script name print("File or Script Name is :", sys.argv[0]) # print arguments other than the file name ...
Read MoreWhat is the purpose of VOLUME in Dockerfile?
Introduction Docker is a popular containerization platform that allows users to package and deploy applications in a standardized and isolated environment. Docker uses a file called a Dockerfile to specify the instructions for building and running a Docker container. One important element of a Dockerfile is the VOLUME instruction, which specifies a mount point for a volume in the container. In this article, we will explore the purpose and usage of volumes in a Dockerfile. Definition of volume in Dockerfile In the context of Docker, a volume is a persistent storage location that exists outside of the container. Volumes ...
Read MoreHow to save all Docker images and copy to another machine?
Introduction Docker images are the building blocks of containerized applications. They are lightweight, portable and can be easily shared between different machines. In this article, we'll take a look at how to save all Docker images on one machine and transfer them to another machine. Method 1: Using docker save and docker load One way to save and transfer Docker images is by using the docker save and docker load commands. The docker save command allows you to save one or more images to a tar archive, which can then be transferred to another machine. The docker load command allows ...
Read MoreHow to flatten a Docker image?
Introduction Flattening a Docker image is the process of creating a new, single-layer image from an existing multi-layer image. Flattening an image can be useful in a variety of scenarios, such as reducing the size of the image, improving the performance of the image, or simplifying the image for easier distribution. A flattened Docker image is an image that consists of a single layer, containing all the files and metadata required for the image to function. This is in contrast to a multi-layer image, which consists of multiple layers stacked on top of each other, each containing a subset of ...
Read MoreHow to execute a script when I terminate a Docker container?
Introduction Executing a script upon container termination is the process of running a script or command when a Docker container is stopped or removed. This can be useful in a variety of scenarios, such as cleaning up resources, logging information, or triggering other actions. Container termination refers to the process of stopping or removing a Docker container. This can be done manually using the docker stop or docker rm commands, or automatically through the use of container orchestration tools or container lifecycle management features. Example 1: ONBUILD To execute a script upon container termination using the ONBUILD Dockerfile command, follow ...
Read MoreHow to cache the RUN npm install instruction when docker builds a Dockerfile?
Introduction When building a Docker image, one of the most time-consuming and resource-intensive steps is running the "RUN npm install" instruction. This instruction installs all the dependencies listed in your package.json file. Caching the results of this instruction can greatly improve the build time of your image. In this article, we will explore different strategies for caching the "RUN npm install" instruction in a Dockerfile. Caching Strategies There are several strategies for caching the "RUN npm install" instruction in a Dockerfile. These include − Using a .dockerignore file − This strategy involves excluding the node_modules directory from being copied ...
Read MoreHow many CPUs does a docker container use?
Introduction Docker containers are a popular way to package and deploy applications. One of the key features of containerization is the ability to isolate resources and limit their usage. In terms of CPU, it is important to know how many CPUs a container can use, as this can greatly impact the performance of the application running inside the container. This article will cover the concepts of CPU resource allocation in Docker, determining the number of CPU available to a container, configuring CPU resources for a container, and advanced techniques for managing CPU resources. Understanding these concepts will help ensure that ...
Read MoreHow can I use a variable inside a Dockerfile CMD?
Introduction Using variables in a Dockerfile CMD can greatly improve the flexibility and maintainability of container configuration. Hardcoding values in a CMD instruction can make it difficult to update or modify the container's configuration in the future. Using variables allows for more dynamic and reusable configurations. Prerequisites The prerequisites for using variables inside a Dockerfile CMD depend on the method you choose to use − Using shell expansion − No specific prerequisites are required. Using the ENV instruction − No specific prerequisites are required. Using the ARG instruction − No specific prerequisites are required. Passing variable at runtime − ...
Read MoreDocker add network drive as volume on windows
Introduction When working with Docker on Windows, it is possible to use network drives as volumes. This allows you to store data on a network drive and access it from within a Docker container. This can be useful in situations where you need to share data between containers, or between the host and the container. With network drive as volume, you can easily store, manage and backup your data in a centralized location and use it with multiple Docker containers. In this article, we will explore the process of adding network drives as volumes in Docker on Windows, and the ...
Read MoreProtect the Docker daemon socket
Introduction The Docker daemon is a background process that manages Docker containers and is responsible for the creation, execution, and deletion of containers. One key component of the Docker daemon is the Docker daemon socket, which is used to communicate with the daemon from the Docker CLI and other applications. It is important to secure the Docker daemon socket to prevent unauthorized access to the Docker daemon and to protect sensitive information that may be exposed through the socket. In this article, we will discuss the location and default permissions of the Docker daemon socket, potential security risks, and best ...
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