[Feature request] Specify target to build in Dockerfile

[Richard87]

Hi!

In for example a nginx+php-fpm deployment, I'm using a multistage docker build

1. Compile javascript assets
2. create a nginx image with all files
3. install php depenencies
4. create a php-fpm image with all files
5. Update deployment with the new nxinx and php-fpm images

[852hamza]

@Richard87 can you assign me this issue

[Richard87]

@852hamza Sorry, I dont have access (I'm not a contributor)

[852hamza]

ok