»Consul Enterprise License


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.

»Binaries with Built In Licenses

If you are downloading Consul from Amazon S3, then the license is included in the binary and you do not need to take further action. This is the most common use case.

In the S3 bucket you will find three Enterprise zip packages. The packages with +pro and +prem in the name, are the binaries that include the license. The package with +ent in the name does not include the license.

When using these binaries no further action is necessary to configure the license.

»Binaries Without Built In Licenses

For Consul Enterprise 1.10.0 or greater, binaries that do not include built in licenses 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 of these are set the order of precedence is:

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

Both client agents and the snapshot agent may also be licensed in the very same manner. However to prevent the need to configure the license on many client agents and snapshot agents those agents have the capability to retrieve the license automatically under specific circumstances.

»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.