Consul Enterprise License

Licensing Overview

All Consul Enterprise agents must be licensed when they are started. Where that license comes from will depend on which binary is in use, whether the agent is a server, client or snapshot agent, and whether ACLs have been enabled for the cluster.

Consul Enterprise 1.14.0, when running on Kubernetes, removed client agents and replaced these with virtual agents. Virtual agents are nodes that Consul service mesh services run on. HashiCorp uses virtual agents to determine license entitlements for customers on per-node licensing and pricing agreements.

Applying a License

For Consul Enterprise 1.10.0 or greater, a license must be available at the time the agent starts. For server agents this means that they must either have the license_path configuration set or have a license configured in the servers environment with the CONSUL_LICENSE or CONSUL_LICENSE_PATH environment variables. Both the configuration item and the CONSUL_LICENSE_PATH environment variable point to a file containing the license whereas the CONSUL_LICENSE environment variable should contain the license as the value. If multiple variables are set, the following order of precedence applies:

1. CONSUL_LICENSE environment variable
2. CONSUL_LICENSE_PATH environment variable
3. license_path configuration item.

Client agents and snapshot agents may also be licensed in the very same manner. However, to avoid the need to configure the license on many client agents and snapshot agents, those agents have the capability to retrieve the license automatically under the conditions described below.

Virtual agents do not need the license to run.

Updating the license for an agent depends on the method you used to apply the license.

• If you used the CONSUL_LICENSE environment variable: After updating the environment variable, restart the affected agents.
• If you used the CONSUL_LICENSE_PATH environment variable: Update the license file first. Then, restart the affected agents.
• If you used the license_path configuration item: Update the license file first. Then, run consul reload for the affected agents.

Client Agent License Retrieval

When a client agent starts without a license in its configuration or environment, it will try to retrieve the license from the servers via RPCs. That RPC always requires a valid non-anonymous ACL token to authorize the request but the token doesn't need any particular permissions. As the license is required before the client actually joins the cluster, where to make those RPC requests to is inferred from the start_join or retry_join configurations. If those are both unset or no agent token is set then the client agent will immediately shut itself down.

If all preliminary checks pass the client agent will attempt to reach out to any server on its RPC port to request the license. These requests will be retried for up to 5 minutes and if it is unable to retrieve a license within that time frame it will shut itself down.

If ACLs are disabled then the license must be provided to the client agent through one of the three methods listed below. Failure in providing the client agent with a licence will prevent the client agent from joining the cluster.

1. CONSUL_LICENSE environment variable
2. CONSUL_LICENSE_PATH environment variable
3. license_path configuration item.

Snapshot Agent License Retrieval

The snapshot agent has similar functionality to the client agent for automatically retrieving the license. However, instead of requiring a server agent to talk to, the snapshot agent can request the license from the server or client agent it would use for all other operations. It still requires an ACL token to authorize the request. Also like client agents, the snapshot agent will shut itself down after being unable to retrieve the license for 5 minutes.