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Varnish Controller

Tag

Tag is an arbitrary name that can be assigned to an agent and a deployment. A tag can be static, which means that a tag was created by an agent. 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.

Example:

tags.png

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.