How to copy folders to docker image from Dockerfile?

Use ADD (docs)

The ADD command can accept as a <src> parameter:

1. A folder within the build folder (the same folder as your Dockerfile). You would then add a line in your Dockerfile like this:

ADD folder /path/inside/your/container

or

2. A single-file archive anywhere in your host filesystem.
   To create an archive use the command:

tar -cvzf newArchive.tar.gz /path/to/your/folder

You would then add a line to your Dockerfile like this:

ADD /path/to/archive/newArchive.tar.gz  /path/inside/your/container

Notes:

• ADD will automatically extract your archive.
• presence/absence of trailing slashes is important, see the linked docs