watchdog: use dig instead of check_dns (#6685)

* watchdog: use dig instead of check_dns

check_dns is slower and uses more system resources,
dig wrapped in a script is a more performant approach and uses
fewer system resources

* added debug mode + compose image bump

---------

Co-authored-by: maxi322 <maxi322@users.noreply.github.com>
Co-authored-by: DerLinkman <niklas.meyer@servercow.de>

data/Dockerfiles/watchdog/Dockerfile

@@ -16,7 +16,6 @@ RUN apk add --update \
   fcgi \
   openssl \
   nagios-plugins-mysql \
-  nagios-plugins-dns \
   nagios-plugins-disk \
   bind-tools \
   redis \
@@ -32,9 +31,11 @@ RUN apk add --update \
   tzdata \
   whois \
   && curl https://raw.githubusercontent.com/mludvig/smtp-cli/v3.10/smtp-cli -o /smtp-cli \
-  && chmod +x smtp-cli
+  && chmod +x smtp-cli \
+  && mkdir /usr/lib/mailcow
 
 COPY watchdog.sh /watchdog.sh
 COPY check_mysql_slavestatus.sh /usr/lib/nagios/plugins/check_mysql_slavestatus.sh
+COPY check_dns.sh /usr/lib/mailcow/check_dns.sh
 
 CMD ["/watchdog.sh"]