docker run has --add-host=[] which is very handy, especially in the network environment without internal DNS. However, docker build don't have --add-host=[] option.

During the image building process, sometimes, we need to have specific name, ip mappings. Such as:

• accessing internal Git server via HTTP with internal domain name;
• accessing some websites (such as, GitHub repo) from inside of GFW, which often contaminated certain domain names;
• accessing internal HTTP API server with internal domain name;

There is a workaround by adding echo 1.2.3.4 >> abc.com /etc/hosts in the begining of each RUN command which has the problems, however it would be handy to have --add-host=[] option in the docker build command.

Related issues:

• docker build should support privileged operations #1916 (comment)
• Allow customization of /etc/hosts, /etc/resolv.conf, etc. in containers #2267
• Cannot append to /etc/hosts in a Dockerfile #3851
• Support --dns or --addn-hosts for docker build #5779
• Need Ability to set Host on Build! #7966
• Proposal: use *run* options when i *build* image #10171
• Please add --add-host=[], --net options to docker build #10324
• Support --dns or --addn-hosts for 'docker build' like 'docker run' #24928