Skip to main content

Posts

Showing posts from October, 2020

Commands used in Dockefile - Part4

  Docker is an opensource tool used for virtualization and deliver software in the form of packages called Containers. It is one of the most important tools used in networking domain.  Dockerfile  is a template for building the image which contains commands needed to package the software. In this post, I am going to explain the commands ADD & COPY used in  Dockerfile .   ADD Command:   ADD command is used to copy files, directories or files from remote URLS to destination path in the image. The source paths can contain wildcards.   If the destination has relative path, it is relative to the Working directory of the image. Note that source path is always relative to the Docker build context.   ADD command will not support authentication. So, if there are any protected files to be added in  Dockerfile  building, use other tools like curl or  wget   Dockerfile  copying Single & Multiple files, directory using ADD inst...

Command used in Dockerfile - Part2

  Docker is an opensource tool used for virtualization and deliver software in the form of packages called Containers. It is one of the most important tools used in networking domain.  Dockerfile  is a template for building the image which contains commands needed to package the software. In this post, I am going to explain the commands ARG & ENV used in  Dockerfile   ARG Command:   ARG command is used to pass the value at build time. Once  ARG variable  is declared in  Dockerfile  its scope starts until the end of the build of  Dockerfile . Containers built from image will not have ARG variables and their  values. There  should be space between Key, Operator and Value while defining ARG variables   Scenario:  Consider the building of image where we are creating one user and the name of the user is defined at build time. In that case, ARG command will be useful. Look the below lines of  Dockerfile  ...

Command Used in Dockerfile - Part1

  Docker is an opensource tool used for virtualization and deliver software in the form of packages called Containers. It is one of the most important tools used in networking domain.  Dockerfile  is a template for building the image which contains commands needed to package the software. In this post, I am going to explain the commands FROM, RUN, LABEL, EXPOSE used in  Dockerfile . In  Dockerfile , each command will be a layer.   FROM Command:   FROM command is used to specify base image. Usually base images from public repositories are pulled and being used. One can search for base images by clicking  here . Common usage of FROM will be like  FROM < Image_Name >:<Tag> . Tag is optional. If tag is not specified, default tag will be  latest .   Some examples of FROM command with common images: FROM ubuntu:14.04 FROM ubuntu:16.04 FROM centos:7 RUN Command:   RUN command is used to run command on top of current image ...