docs: complete DNS ADR

docs/ADR/004-DNS.md

@@ -1,10 +1,12 @@
-# 004 DNS
+# DNS
 
-## Status
+## 001 Recursor out off NAS
 
-In progress
+### Status
 
-## Context
+done
+
+### Context
 
 curently main local domain DNS is located on NAS.
 
@@ -13,19 +15,62 @@ goal:
 - avoid DNS outtage in case of NAS reboot (my synology have 10 years and is a litle long to reboot) morever during NAS reboot we lost the adblock DNS in the nomad cluster because nomad depend of the NFS share.
 - remove the direct redirection to service.consul DNS and the IPTABLE rule use to redirect port 53 on consul on gerard instead new DNS could be forward directly to an active consul node on port 8300
 
-### DNS software
+#### DNS software
 
 need DHCP Dynamic update
 could redirect domain on other port than port 53
 
-## Decision
+### Decision
 
 we will migrate Main Domain DNS from NAS to gerard  (powerDNS)
 powerDNS provide two disting binaries one for authority server one other for recursor
 goal is to first migrate the recursice part from synology to a physical service
 and in second time migrate authority server in nmad cluster
 
-## Consequences
+### Consequences
 
 before to move authority server need to remove DB dns dependance (create db consul services)
 need to delete the iptable rule on gerard before deploy
+
+## 002 each node request self consul client for consul dns query
+
+### Status
+
+done
+
+### Context
+
+to avoid a cluster failled in case of the DNS recursor default.
+I would like that each cluster client request their own consul client
+first to resolve consul DNS query
+
+### Decision
+
+Implement sytemd-resolved on all cluster member and add a DNS redirection
+
+### Consequences
+
+need to modify annsible system role for systemd-resolved activation and consul role for configure redirection
+
+## 003 migrate recurson in cluster
+
+### Status
+
+Study
+
+### Context
+
+now that cluster doesn't depend of recursor because request self consul agent for consul query need
+need to study if we can migrate recursor in nomad wihout break dependance
+advantage:
+
+- recursor could change client in case of faillure
+
+agains:
+
+- this job need a keepalive IP like pihole
+- loss recursor if lost nomad cluster
+
+### Decision
+
+### Consequences