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-add
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
Verify if the link has been extracted onto the container
/ # 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.