Docker Add vs Copy

copy and add commands both are used to copy the files into docker image
but we use each one in different cases. In the following examples i will show you what is the difference between docker add and copy commands.

Docker File Copy Command 

if you want to copy the files from local machine to docker image you can use copy command

COPY  <src>  <dest>

COPY  /path/to/the/file/in/your/system   /destination/path/in/docker/image

COPY . /project
Here we are copying all files into project folder in docker image

Docker File ADD Command 

If you want copy or download the files from remote location to docker image you can use add command.

ADD  <src>  <dest>

ADD /source/file/url/path       /destination/path/in/docker/image

Ex1:

ADD http://mirrors.estointernet.in/apache/maven/maven-3/3.6.0/binaries/apache-maven-3.6.0-bin.tar.gz /opt

Here maven tar file will be downloaded from above URL and it will be placed in opt directory in docker image.

And also it will extract the maven tar file in opt directory in docker image. So add command we can use in two ways
one is to download the files from remote URL to docker image and to extract the files.

Ex2:

In the previous example we downloaded a maven tar file and extracted into docker opt directory. Let's say that if you have zip or any tar files in your system and if you want send those tar or zip files to docker image and extract. in this case also we can use same ADD command.

ADD <src> <dest>

ADD abcd.tar.gz   /opt

here abcd.tar.gz in your system and it will be copied into opt directory in docker image and extracted.