add opensearch addons

opensearch-nginx-lb/rootfs/config/nginx.conf

@@ -0,0 +1,13 @@
+events {}
+http {
+    upstream opensearch_coord {
+        server os-coord-1:9200;
+        server os-coord-2:9200;
+    }
+    server {
+        listen 9200;
+        location / {
+            proxy_pass http://opensearch_coord;
+        }
+    }
+}

opensearch-nginx-lb/rootfs/etc/s6-overlay/s6-rc.d/nginx/finish

@@ -0,0 +1,3 @@
+#!/command/execlineb -S0
+# Prevent restart loops; allow clean exit
+exit 0

opensearch-nginx-lb/rootfs/etc/s6-overlay/s6-rc.d/nginx/run

@@ -0,0 +1,4 @@
+#!/command/with-contenv bash
+set -euo pipefail
+echo "[s6-run] Starting NGINX load balancer"
+exec nginx -g 'daemon off;'