dns.env file did not work out, env_file: element not being read before dns: element. Using folder-specific .env files instead, seems to be loaded before dns: element. Also move other values to the env files for better password privacy.

Config/Nextcloud/.env.example

@@ -0,0 +1,26 @@
+# Environment file for Nextcloud stack.
+
+## Nextcloud ##
+
+PHP_UPLOAD_LIMIT=5G
+
+## MySQL ##
+
+MYSQL_HOST=db
+MYSQL_DATABASE=nextcloud
+MYSQL_ROOT_PASSWORD=ChangeMe
+MYSQL_USER=nc
+MYSQL_PASSWORD=changeme
+
+## REDIS ##
+
+REDIS_HOST=redis
+REDIS_HOST_PASSWORD=someredispassword
+
+## Other ##
+
+# If you have both Nextcloud and OnlyOffice on the same internal network you
+#   will likely want to set this to an internal DNS server. Some routers will
+#   drop traffic if an internal IP tries to communicate with the WAN IP, causing
+#   the curl to OnlyOffice's /healthcheck to fail. Do the same in both configs.
+DNS=192.168.1.1