»Lease Count Quotas
Vault features an extension to resource quotas that allows operators to enforce
limits on how many leases are created. For a given lease count quota, if the
number of leases in the cluster hits the configured limit,
lease creations will be forbidden for all clients until a lease has been revoked
or has expired.
It is important to note that lease count quotas do not apply to the root tokens.
If the number of leases in the cluster hits the configured limit,
an operator could still create a root token and access the cluster to try to recover.
All the nodes in the Vault cluster will share the lease quota rules, meaning that the lease counters will be shared, regardless of which node in the Vault cluster receives lease generation requests. Lease quotas can be imposed across Vault's API, or scoped down to API pertaining to specific namespaces or specific mounts.
Lease count quotas defined in a namespace will be inherited by all the child
namespaces. By extension, this means that a quota that is defined in the
namespace is inherited by all namespaces and mounts, essentially to the entire
Lease count quotas defined on a namespace will take precedence over the inherited quotas. Lease count quotas defined for a mount will take precedence over inherited and namespace quotas. The limits on the namespace and mount quotas can either be increased or decreased. If the inherited quota is very restrictive and if it is desired to relax the limits in one namespace, or on a specific mount, it can be done using this precedence model. On the other hand, if the inherited quota is very liberal and if it is desired to further restrict usages in a specific namespace or mount, that can be done using the precedence model too.
Vault also allows the inspection into the state of lease count quotas in a Vault cluster through various metrics exposed and through enabling optional audit logging.
Refer to Protecting Vault with Resource Quotas for a step-by-step tutorial.
Lease count quotas can be managed over the HTTP API. Please see Lease Count Quotas API for more details.