This is a two part proposal. Please see #7467 for the other part.

Problem

Links currently do not satisfy the needs of users for a couple of reasons:

• linking is static: you cannot change the associations links provide without destroying (at least one) container
• docker’s links system externally does not provide an elegant UI to manipulating and querying links

Solution:

• Provide new docker links UI
• Provide guarantees about what happens when a link is added or removed

New docker links UI

Four new inferior commands will be added under the new subcommand docker links

• docker links list - list the existing links, and the state of the linked containers
• docker links add <consumer> <producer> <name> - add a link to existing containers
• docker links remove <name> - remove a link from existing containers
• docker links move <name> <producer2> - to migrate a set of links from one container to another

Links Guarantees

We should guarantee that:

• Adding a link should:
  • rewrite the hosts files for all linked resources with updated content
  • expose the ports described in the Dockerfile
• Removing a link should:
  • rewrite the hosts files for all linked resources with updated content
  • tear down the exposed ports brought by docker links add

Tickets Resolved:

#5186
#2733
#3285
#3155
#2658
#2588 (I think)