How to get Structured Logging on GCP with Telemere

telemere-gcp-structured-logs.clj

(def gcp-json-handler
  (tele/handler:console
    {:output-fn (tele/pr-signal-fn
                  {:pr-fn    jsonista.core/write-value-as-string
                   :clean-fn (tele/clean-signal-fn {:incl-kvs? true})})}))

(def encore-levels->gcp-severity
  {:trace  :DEFAULT  ; (0) The log entry has no assigned severity level.
   :debug  :DEBUG    ; (100) Debug or trace information.
   :info   :INFO     ; (200) Routine information, such as ongoing status or performance.
   :warn   :WARNING  ; (400) Warning events might cause problems.
   :error  :ERROR    ; (500) Error events are likely to cause problems.
   :fatal  :CRITICAL ; (600) Critical events cause more severe problems or outages.
   :report :ALERT})     ; (700) A person must take an action immediately.

(tele/add-handler!
  :default/console
  gcp-json-handler
  {:ns-filter  {:disallow "org.eclipse.jetty.server.*"}
   :middleware (fn [{:as   signal
                     :keys [level]}]
                 (assoc signal :severity (get encore-levels->gcp-severity level)))})