Check xtdb indexing in healthcheck endpoint?

[peter-wilkins]

We are using ECS and during deployments the load balancers are switched before site is functional.
We suspect it is due to xtdb indexing.
Would it be useful to check if xtdb lag is within a threshold in wrap-healthcheck?

(defn xtdb-tx-lag []
  (let [node (xtdb-node)
        tx-id (fn [tx] (get tx ::xt/tx-id 0))]
    (- (tx-id (xt/latest-submitted-tx node))
       (tx-id (xt/latest-completed-tx node)))))