fix: send container metrics directly to prometheus

config.alloy.tmpl

@@ -44,6 +44,7 @@ prometheus.scrape "default" {
     prometheus.exporter.self.alloy.targets,
     prometheus.exporter.unix.default.targets,
     prometheus.exporter.cadvisor.docker.targets,
+    discovery.docker.containers.targets,
   )
 
   forward_to = [prometheus.remote_write.prometheus.receiver]
@@ -60,6 +61,11 @@ prometheus.remote_write "prometheus" {
   }
 }
 
+discovery.docker "containers" {
+  host                = "unix:///var/run/docker.sock"
+  match_first_network = false
+}
+
 // Scrape Prometheus metrics from other containers on this host.
 // Containers opt in via Docker labels:
 //   prometheus.io/scrape=true        required: enable scraping