Varnish Controller


Tag is an arbitrary name that can be assigned to an agent, router and a deployment. A tag can be static, which means that a tag was created by an agent or a router. Tags control which agents are to be selected for a specific deployment.

Both agent and deployment can have multiple tags assigned to them. All tags in a deployment must exist in an agent in order to be deployed to that agent. The agent can have more tags than a deployment.



Figure 1. Tags

  • Agent1 tags: prod, eu
  • Agent2 tags: prod, us
  • Agent3 tags: prod, eu, berlin
  • Deployment tags: prod, eu
  • The deployment will be deployed to Agent1 and Agent3 but not Agent2 (since it’s missing eu)

A static tag can be removed, but if the agent is still active it will present the static tag to the system again, and the tag will be re-created in the system. If there are no agents reporting in static tags the static tag can be removed completely. A static tag is used as any other tag in the system; the only difference is that it was created by the agent itself.

Creating and assigning tags to agents is usually something that is done once.

Tags on routers are used for a specific routing rule decision called tags.