Add config file template for documentMaxLength setting

.env.sample

@@ -41,3 +41,5 @@ COMPOSE_FILE="compose.yml"
 # CMD_DEFAULT_PERMISSION=editable
 # CMD_EMAIL=true
 # CMD_SESSION_LIFE=1209600000
+# Only present in config.json (no equivalent env var):
+# DOCUMENT_MAX_LENGTH=100000

compose.yml

@@ -40,6 +40,9 @@ services:
       - source: entrypoint_conf
         target: /docker-entrypoint.sh
         mode: 0555
+      - source: config_json
+        target: /files/config.json
+        mode: 0700
     deploy:
       restart_policy:
         condition: on-failure
@@ -90,6 +93,10 @@ networks:
     external: true
   internal:
 configs:
+  config_json:
+    name: ${STACK_NAME}_config_${ENTRYPOINT_CONF_VERSION}
+    file: config.json.tmpl
+    template_driver: golang
   entrypoint_conf:
     name: ${STACK_NAME}_entrypoint_${ENTRYPOINT_CONF_VERSION}
     file: entrypoint.sh.tmpl

config.json.tmpl

@@ -0,0 +1,5 @@
+{
+{{ if (env "DOCUMENT_MAX_LENGTH") }}
+  "documentMaxLength": {{ env "DOCUMENT_MAX_LENGTH" }}
+{{ end }}
+}