feat: enhance BGP template and peer configuration handling. Introduce policies_json parameter for local IP and ASN overrides in BGP speakers. Implement BGP template rendering and update peer configuration to utilize templates, improving flexibility in BGP setup. Add tests for new rendering logic and ensure proper integration with existing configurations.

internal/birdfmt/testdata/golden/main_bird_skeleton.golden

@@ -2,6 +2,7 @@ router id 192.0.2.1;
 
 include "bird.d/evobgp_filters_v4.conf";
 include "bird.d/evobgp_filters_v6.conf";
+include "bird.d/evobgp_bgp_template.conf";
 include "bird.d/evobgp_prefixes_v4.conf";
 include "bird.d/evobgp_prefixes_v6.conf";
 include "bird.d/evobgp_peers.conf";

internal/birdfmt/testdata/scenarios/standard_layout/bird.conf

@@ -5,6 +5,7 @@ router id 192.0.2.1;
 
 include "bird.d/evobgp_filters_v4.conf";
 include "bird.d/evobgp_filters_v6.conf";
+include "bird.d/evobgp_bgp_template.conf";
 include "bird.d/evobgp_prefixes_v4.conf";
 include "bird.d/evobgp_prefixes_v6.conf";
 include "bird.d/evobgp_peers.conf";

internal/birdfmt/testdata/scenarios/standard_layout/bird.d/evobgp_bgp_template.conf

@@ -0,0 +1,15 @@
+template bgp bgp_template {
+    local 192.0.2.1 as 65001;
+    ipv4 {
+        import all;
+        export filter evobgp_export_v4;
+    };
+}
+
+template bgp bgp_template_v6 {
+    local 2001:db8::1 as 65001;
+    ipv6 {
+        import all;
+        export filter evobgp_export_v6;
+    };
+}

internal/birdfmt/testdata/scenarios/standard_layout/bird.d/evobgp_peers.conf

@@ -1,8 +1,6 @@
-protocol bgp evobgp_peer_ci {
-    local 192.0.2.1 as 65001;
+protocol bgp evobgp_peer_ci from bgp_template {
     neighbor 192.0.2.2 as 65002;
-    ipv4 {
-        import all;
-        export filter evobgp_export_v4;
-    };
+    multihop;
+    source address 192.0.2.1;
+    passive;
 }