If ignore_lease is set, etcd updates the key using its current lease. Returns an error if the key does not exist.

If ignore_value is set, etcd updates the key using its current value. Returns an error if the key does not exist.

key is the key, in bytes, to put into the key-value store.

lease is the lease ID to associate with the key in the key-value store. A lease value of 0 indicates no lease.

If prev_kv is set, etcd gets the previous key-value pair before changing it. The previous key-value pair will be returned in the put response.

value is the value, in bytes, to associate with the key in the key-value store.