Update DeckHand Chart - Multi-Threads/Workers

This p.s. will allow multi-thread/worker parameters to be
configurable in the Deckhand chart so that the values can
be injected into the pod environment. This is a follow up
to the comments made in [0].

Note also that we will need multiple workers in order to
handle concurrent requests from Armada and DryDock to DeckHand
for the rendered document. Multi-threads with single worker
did not work as expected. Test results from our lab environment
suggests that 4 single-threaded workers will be sufficient
for our purpose. Hence we will use that as default override
values for now.

[0] https://review.gerrithub.io/#/c/393679/

Change-Id: I228713ec7b2ec305cbc2c761bc77125ea98e7dfa

charts/deckhand/templates/deployment.yaml

@@ -44,6 +44,11 @@ spec:
 {{ tuple $envAll $dependencies $mounts_deckhand_init | include "helm-toolkit.snippets.kubernetes_entrypoint_init_container" | indent 8 }}
       containers:
         - name: deckhand
+          env:
+            - name: 'DECKHAND_API_WORKERS'
+              value: {{ .Values.conf.uwsgi.workers | default 4 | quote }}
+            - name: 'DECKHAND_API_THREADS'
+              value: {{ .Values.conf.uwsgi.threads | default 1 | quote }}
           image: {{ .Values.images.tags.deckhand }}
           imagePullPolicy: {{ .Values.images.pull_policy }}
 {{ tuple $envAll $envAll.Values.pod.resources.api | include "helm-toolkit.snippets.kubernetes_resources" | indent 10 }}

charts/deckhand/values.yaml

@@ -181,6 +181,9 @@ database:
     db_root_user: postgres
 
 conf:
+  uwsgi:
+    threads: 1
+    workers: 4
   policy:
     admin_api: role:admin
     deckhand:create_cleartext_documents: rule:admin_api