T9073: frr-exporter: add CLI support for optional collectors and collector options

frr_exporter v1.5.0 enables the bgp, ospf, bfd and route collectors by
default, while bgpl2vpn, pim and vrrp must be enabled explicitly. Expose
bgpl2vpn (CLI: bgp-l2-vpn) and pim under "service monitoring prometheus
frr-exporter collector", following the same CLI style as the
node-exporter collectors node. The vrrp collector is not exposed since
VyOS implements VRRP with keepalived and FRR's vrrpd is never started.

Also expose the collector options available in v1.5.0:
  - collector bgp accept-filtered-prefixes
  - collector bgp advertised-prefixes
  - collector bgp peer-description <json|plain-text>
  - collector bgp peer-group
  - collector bgp peer-hostname
  - collector bgp peer-type
  - collector ospf-instance <id>
  - collector detailed-routes

The bgp.* options are shared by the bgp, bgp6 and bgpl2vpn collectors
upstream. The bgp6 collector remains unconditionally enabled, hence
existing configurations render the same ExecStart and no migration is
required.

Includes code generated by Claude Code

1 files changed, 35 insertions, 1 deletions

diff --git a/data/templates/prometheus/frr_exporter.service.j2 b/data/templates/prometheus/frr_exporter.service.j2
index f80bad2cd..a2723ffd9 100644
--- a/data/templates/prometheus/frr_exporter.service.j2
+++ b/data/templates/prometheus/frr_exporter.service.j2
@@ -9,7 +9,41 @@ After=network.target
 User=frr
 {% endif %}
 ExecStart={{ vrf_command }}/usr/sbin/frr_exporter \
-          --collector.bgp6 \
+        --collector.bgp6 \
+{% if optional_collectors is vyos_defined %}
+{%     for collector in optional_collectors %}
+        --collector.{{ collector }} \
+{%     endfor %}
+{% endif %}
+{% if collector is vyos_defined %}
+{%     if collector.bgp.accept_filtered_prefixes is vyos_defined %}
+        --collector.bgp.accepted-filtered-prefixes \
+{%     endif %}
+{%     if collector.bgp.advertised_prefixes is vyos_defined %}
+        --collector.bgp.advertised-prefixes \
+{%     endif %}
+{%     if collector.bgp.peer_description is vyos_defined %}
+        --collector.bgp.peer-descriptions \
+{%         if collector.bgp.peer_description is vyos_defined('plain-text') %}
+        --collector.bgp.peer-descriptions.plain-text \
+{%         endif %}
+{%     endif %}
+{%     if collector.bgp.peer_group is vyos_defined %}
+        --collector.bgp.peer-groups \
+{%     endif %}
+{%     if collector.bgp.peer_hostname is vyos_defined %}
+        --collector.bgp.peer-hostnames \
+{%     endif %}
+{%     if collector.bgp.peer_type is vyos_defined %}
+        --collector.bgp.peer-types \
+{%     endif %}
+{%     if collector.ospf_instance is vyos_defined %}
+        --collector.ospf.instances={{ collector.ospf_instance | join(',') }} \
+{%     endif %}
+{%     if collector.detailed_routes is vyos_defined %}
+        --collector.route.detailed-routes \
+{%     endif %}
+{% endif %}
 {% if listen_address is vyos_defined %}
 {%     for address in listen_address %}
         --web.listen-address={{ address | bracketize_ipv6 }}:{{ port }}