dovecot: Add basic metric definitions

This adds basic metric definitions across a number of different events,
to be expanded upon as needed in the future. Several metrics are given
additional vectors with low cardinality.

service/dovecot/container/config/conf.d/10-metrics.conf

@@ -0,0 +1,54 @@
+service stats {
+    inet_listener http {
+        port = 9900
+    }
+}
+
+# Authentication metrics.
+metric auth_passdb_request {
+    filter = event=auth_passdb_request_finished
+    fields = passdb_name result
+}
+
+metric auth_userdb_request {
+    filter = event=auth_userdb_request_finished
+    fields = userdb_name result
+}
+
+# Connection metrics.
+metric client_connection {
+    filter = event=client_connection_connected
+}
+
+metric server_connection {
+    filter = event=server_connection_connected
+}
+
+# HTTP client metrics.
+metric http_client_request {
+    filter = event=http_request_finished
+    fields = status_code
+}
+
+# IMAP command metrics.
+metric imap_command {
+    filter = event=imap_command_finished
+    fields = user cmd_name tagged_reply_state
+}
+
+# SQL metrics.
+metric sql_query {
+    filter = event=sql_query_finished
+    fields = query error_code
+}
+
+# Sieve metrics.
+metric sieve_script {
+    filter = event=sieve_runtime_script_finished
+    fields = script_name error
+}
+
+metric sieve_action {
+    filter = event=sieve_action_finished
+    fields = action_name
+}

service/dovecot/container/config/conf.d/90-stats.conf

@@ -1,5 +0,0 @@
-service stats {
-    inet_listener http {
-        port = 9900
-    }
-}