tweak logging

recipes/files/config.alloy

 # see also https://grafana.com/docs/alloy/latest/tutorials/send-logs-to-loki/
 
+loki.relabel "journal" {
+  forward_to = []
+
+  rule {
+    source_labels = ["__journal_priority"]
+    target_label  = "level"
+  }
+  rule {
+    source_labels = ["__journal__hostname"]
+    target_label  = "hostname"
+  }
+  rule {
+    source_labels = ["__journal__comm"]
+    target_label  = "comm"
+  }
+  rule {
+    source_labels = ["__journal__systemd_unit"]
+    target_label  = "systemd_unit"
+  }
+  rule {
+    source_labels = ["__journal_unit"]
+    target_label  = "unit"
+  }
+}
+
 loki.source.journal "journal_scrape" {
   forward_to = [loki.process.filter_logs.receiver]
-  format_as_json = true
+  relabel_rules = loki.relabel.journal.rules
 }
 
 loki.process "filter_logs" {
-  // stage.drop {
-  //  source = ""
-  //  expression  = ".*Connection closed by authenticating user root"
-  //  drop_counter_reason = "noisy"
-  //}
+  stage.drop {
+    source = "systemd_unit,unit"
+    expression = "serial-getty@ttyS0.service"
+    drop_counter_reason = "ignore ttyS0 errors"
+  }
   forward_to = [loki.write.lcu_loki.receiver, loki.write.central_loki.receiver]
 }
 
 loki.write "lcu_loki" {
   endpoint {
     url = "http://loki.service.consul:3100/loki/api/v1/push"
-
-    // basic_auth {
-    //  username = "admin"
-    //  password = "admin"
-    // }
   }
 }
 
 loki.write "central_loki" {
   endpoint {
     url = "http://logs.service.lofar-central.consul:3100/loki/api/v1/push"
-
-    // basic_auth {
-    //  username = "admin"
-    //  password = "admin"
-    // }
   }
 }