Use balancer_by_lua_block in token_server.conf

* Remove `YT_POT_BGUTIL_BASE_URL`

* Prioritize the linked container details

config/root/etc/nginx/nginx.conf

@@ -9,7 +9,13 @@ worker_processes auto;
 worker_cpu_affinity auto;
 pid /run/nginx.pid;
 
-env YT_POT_BGUTIL_BASE_URL;
+# link configuration
+env POTSERVER_PORT_4416_TCP_ADDR;
+env POTSERVER_PORT_4416_TCP_PORT;
+# user configuration
+env TUBESYNC_POT_HTTPS;
+env TUBESYNC_POT_IPADDR;
+env TUBESYNC_POT_PORT;
 
 events {
     worker_connections 1024;

config/root/etc/nginx/token_server.conf

@@ -1,5 +1,68 @@
+lua_shared_dict token_server 1m;
 upstream token_server {
     server 127.0.0.1:4406 max_fails=0;
+
+    balancer_by_lua_block {
+        local balancer = require "ngx.balancer"
+        local upstream = ngx.shared.token_server
+        local exit_error = ngx.HTTP_INTERNAL_SERVER_ERROR
+
+        local ok, err, empty_port, host, port
+        local default_host, default_port, tries = '127.0.0.1', '4406', 1
+
+        local user_host = os.getenv('TUBESYNC_POT_IPADDR')
+        local link_host = os.getenv('POTSERVER_PORT_4416_TCP_ADDR')
+        local use_https = os.getenv('TUBESYNC_POT_HTTPS')
+        if user_host and use_https then
+            use_https = true
+            empty_port = '443'
+        else
+            use_https = false
+            empty_port = '80'
+        end
+
+        ok, err = balancer.get_last_failure()
+        if ok then
+            host, port, tries = default_host, default_port, 0
+        elseif link_host then
+            host = link_host
+            local link_port = os.getenv('POTSERVER_PORT_4416_TCP_PORT')
+            if link_port then
+                port = link_port
+            else
+                port = empty_port
+            end
+        elseif user_host then
+            host = user_host
+            local user_port = os.getenv('TUBESYNC_POT_PORT')
+            if user_port then
+                port = user_port
+            else
+                port = empty_port
+            end
+            ok, err = balancer.set_upstream_tls(use_https)
+            if not ok then
+                ngx.log(ngx.ERR, "failed to set upstream TLS: ", err)
+            end
+        end
+        if not host then
+            host, port, tries = default_host, default_port, 0
+        end
+
+        ok, err = balancer.set_more_tries(tries)
+        if not ok then
+            ngx.log(ngx.err, ("failed to set tries to %d: "):format(tries), err)
+        end
+
+        ok, err = balancer.set_current_peer(host, port)
+        if ok then
+            upstream:set('addr', host)
+            upstream:set('port', port)
+        else
+            ngx.log(ngx.err, "failed to set the current peer: ", err)
+            return ngx.exit(exit_error)
+        end
+    }
 }
 
 server {
@@ -11,19 +74,7 @@ server {
     # Server domain name
     server_name _;
 
-    set_by_lua_block $pot_url {
-        local default = 'http://token_server'
-        local url = os.getenv('YT_POT_BGUTIL_BASE_URL')
-        if not url then
-            return default
-        end
-        if #url and url:find('://') then
-            return url
-        end
-        return default
-    }
-
     location / {
-        proxy_pass $pot_url;
+        proxy_pass http://token_server;
     }
 }

config/root/etc/s6-overlay/s6-rc.d/nginx/run

@@ -2,15 +2,4 @@
 
 cd /
 
-https="${TUBESYNC_POT_HTTPS:+https}"
-ip_address="${TUBESYNC_POT_IPADDR:-${POTSERVER_PORT_4416_TCP_ADDR}}"
-: "${TUBESYNC_POT_PORT:=${POTSERVER_PORT_4416_TCP_PORT}}"
-port="${TUBESYNC_POT_PORT:+:}${TUBESYNC_POT_PORT}"
-
-if [ -n "${ip_address}" ]
-then
-    YT_POT_BGUTIL_BASE_URL="${https:-http}://${ip_address}${port}"
-    export YT_POT_BGUTIL_BASE_URL
-fi
-
 exec /usr/bin/openresty -c /etc/nginx/nginx.conf -e stderr