logs: add -posthog thread

desk/ted/posthog.hoon

@@ -0,0 +1,61 @@
+::  posthog: submit an log event to PostHog
+::
+/-  spider
+/+  io=strandio, l=logs
+::
+=+  posthog-key='phc_GyI5iD7kM6RRbb1hIU0fiGmTCh4ha44hthJYJ7a89td'
+=+  posthog-url='https://eu.i.posthog.com/capture/'
+=+  posthog-retry=3
+=+  posthog-retry-delay=~s30
+::
+=,  strand=strand:spider
+^-  thread:spider
+::  .arg: a pair of origin agent and log item
+::
+|=  arg=vase
+=/  m  (strand ,vase)
+^-  form:m
+=+  !<(arg=(unit (pair @tas log-item:l)) arg)
+?>  ?=(^ arg)
+=*  agent  p.u.arg
+=*  log-item  q.u.arg
+;<  =bowl:strand  bind:m  get-bowl:io
+=/  log-event-json=$>(%o json)  (log-event:enjs:l event.log-item)
+=/  props=json
+  :-  %o
+  %-  ~(uni by p.log-event-json)
+  ^-  (map @t json)
+  %-  my
+  :~  'distinct_id'^s+(scot %p our.bowl)
+      'agent'^s+agent
+  ==
+=/  event=json
+  %-  pairs:enjs:format
+  :~  'api_key'^s+posthog-key
+      timestamp/(id-event:enjs:l id.log-item)
+      event/s+'Backend Log'
+      properties+props
+  ==
+::
+=/  =request:http
+  :*  %'POST'
+      posthog-url
+      ~['content-type'^'application/json']
+      `(as-octs:mimes:html (en:json:html event))
+  ==
+|-
+?:  =(0 posthog-retry)
+  (pure:m !>(~))
+;<  ~  bind:m  (send-request:io request)
+;<  =client-response:iris  bind:m  take-client-response:io
+::NOTE  this logic must be adjusted when %iris supports
+::      partial responses
+?.  ?&  ?=(%finished -.client-response)
+        =(200 status-code.response-header.client-response)
+    ==
+  ?>  ?=(%finished -.client-response)
+  =*  status-code  status-code.response-header.client-response
+  %-  (slog leaf+"posthog request failed: status {<status-code>}" ~)
+  ;<  ~  bind:m  (sleep:io posthog-retry-delay)
+  $(posthog-retry (dec posthog-retry))
+(pure:m !>(`client-response))