dns: T5959: Streamline dns forwarding service

Streamline configuration and operation of dns forwarding service in
following ways:

- Remove `dns_forwarding_reset.py` as its functionality is now covered
  by `dns.py`
- Adjust function names in `dns.py` to disambiguate between DNS
  forwarding and dynamic DNS
- Remove `dns_forwarding_restart.sh` as its functionality is inlined in
  `dns-forwarding.xml`
- Templatize systemd override for `pdns-recursor.service` and move the
  generated override files in /run. This ensures that the override files
  are always generated afresh after boot
- Simplify the systemd override file by removing the redundant overrides
- Relocate configuration path for pdns-recursor to `/run/pdns-recursor`
  and utilize the `RuntimeDirectory` default that pdns-recursor expects
- We do not need to use custom `--socket-dir` path anymore, the default
  path (viz., `/run/pdns-recursor` is fine)

(cherry picked from commit 1c1fb5fb4bd7c0d205b28caf90357ad56423464f)

3 files changed, 11 insertions, 3 deletions

diff --git a/data/templates/dns-forwarding/override.conf.j2 b/data/templates/dns-forwarding/override.conf.j2
new file mode 100644
index 000000000..9d81a2977
--- /dev/null
+++ b/data/templates/dns-forwarding/override.conf.j2
@@ -0,0 +1,8 @@
+[Unit]
+ConditionPathExists={{ config_file }}
+After=vyos-router.service
+
+[Service]
+RuntimeDirectoryPreserve=yes
+ExecStart=
+ExecStart=/usr/sbin/pdns_recursor --daemon=no --write-pid=no --disable-syslog --log-timestamp=no --config-dir={{ config_dir }}
diff --git a/data/templates/dns-forwarding/recursor.conf.j2 b/data/templates/dns-forwarding/recursor.conf.j2
index 55b37732b..e4e8e7044 100644
--- a/data/templates/dns-forwarding/recursor.conf.j2
+++ b/data/templates/dns-forwarding/recursor.conf.j2
@@ -12,7 +12,7 @@ allow-from={{ allow_from | join(',') }}
 log-common-errors=yes
 non-local-bind=yes
 query-local-address={{ source_address | join(',') }}
-lua-config-file=recursor.conf.lua
+lua-config-file={{ config_dir }}/recursor.conf.lua
 
 # cache-size
 max-cache-entries={{ cache_size }}
@@ -56,4 +56,4 @@ serve-rfc1918={{ 'no' if no_serve_rfc1918 is vyos_defined else 'yes' }}
 # zones
 auth-zones={% for z in authoritative_zones %}{{ z.name }}={{ z.file }}{{- "," if not loop.last -}}{% endfor %}
 
-forward-zones-file=recursor.forward-zones.conf
+forward-zones-file={{ config_dir }}/recursor.forward-zones.conf
diff --git a/data/templates/dns-forwarding/recursor.conf.lua.j2 b/data/templates/dns-forwarding/recursor.conf.lua.j2
index 816f69160..8026442c7 100644
--- a/data/templates/dns-forwarding/recursor.conf.lua.j2
+++ b/data/templates/dns-forwarding/recursor.conf.lua.j2
@@ -5,4 +5,4 @@
 dofile("/usr/share/pdns-recursor/lua-config/rootkeys.lua")
 
 -- Load lua from vyos-hostsd --
-dofile("recursor.vyos-hostsd.conf.lua")
+dofile("{{ config_dir }}/recursor.vyos-hostsd.conf.lua")