Lab #2: Create an image with ADD instruction

COPY and ADD are both Dockerfile instructions that serve similar purposes. They let you copy files from a specific location into a Docker image.

COPY takes in a src and destination. It only lets you copy in a local file or directory from your host (the machine building the Docker image) into the Docker image itself.

ADD lets you do that too, but it also supports 2 other sources. First, you can use a URL instead of a local file / directory. Secondly, you can extract a tar file from the source directly into the destination.

Pre-requisite:

Tested Infrastructure

Platform Number of Instance Reading Time
Play with Docker 1 5 min

Pre-requisite

  • Create an account with DockerHub
  • Open PWD Platform on your browser
  • Click on Add New Instance on the left side of the screen to bring up Alpine OS instance on the right side

Assignment:

  • Create an image with ADD instruction
  • Tag your image as labs-add:v1.0
  • Create a container based on that image, and see the extracted tar file.

Creating Dockerfile

FROM alpine:3.5
RUN apk update
ADD http://www.vlsitechnology.org/pharosc_8.4.tar.gz .

Build Docker Image

docker build -t saiyam911/alpine-add . -f <name of dockerfile>

Tagging image as labs-git

docker tag saiyam911/alpine-add saiyam911/labs-add:v1.0

Verify the Images

$ docker images
REPOSITORY                   TAG                 IMAGE ID            CREATED             SIZE
saiyam911/alpine-add        latest              cdf97cb49d48        38 minutes ago       300MB
saiyam911/labs-add          v1.0                cdf97cb49d48        38 minutes ago       300MB

Create a container

docker run -itd saiyam911/labs-add:v1.0 /bin/sh

$ docker ps
CONTAINER ID        IMAGE                      COMMAND             CREATED             STATUS              PORTS               NAMES
f0940750f61a        saiyam911/labs-add:v1.0   "/bin/sh"           20 seconds ago      Up 18 seconds                           distracted_darwin

Enter into Container Shell

docker attach f094

Please press “Enter” key twice so as to enter into container shell

/ # ls -ltr
-rw-------    1 root     root     295168000 Sep 19  2007 pharosc_8.4.tar.gz

ADD Command lets you to add a tar directly from a link and explode to the container.

Next » Create an image with COPY instruction