Move to bind instead of coredns

Signed-off-by: Knut Ahlers <knut@ahlers.me>

.dockerignore

@@ -0,0 +1,4 @@
+zones/db.*
+zones/named.conf
+*.pyc
+.venv

.gitignore

@@ -1,2 +1,2 @@
-zones/db.*
+zones/*
 *.pyc

Corefile

@@ -1,10 +0,0 @@
-. {
-  auto {
-    directory zones db\.(.*) {1} 10
-    reload 10s
-    upstream 8.8.8.8
-  }
-
-  errors
-  log
-}

Dockerfile

@@ -2,13 +2,16 @@ FROM alpine
 
 LABEL maintainer Knut Ahlers <knut@ahlers.me>
 
-ADD . /src
-WORKDIR /src
+COPY build.sh         /src/
+COPY requirements.txt /src/
 
 RUN set -ex \
  && apk --no-cache add bash \
  && /src/build.sh
 
+COPY . /src
+WORKDIR /src
+
 EXPOSE 53/udp 53
 
 VOLUME ["/src/zones"]
@@ -17,4 +20,4 @@ HEALTHCHECK --interval=30s --timeout=5s \
   CMD dig +short @localhost health.server.test TXT || exit 1
 
 ENTRYPOINT ["/src/docker-entrypoint.sh"]
-CMD ["coredns"]
+CMD ["named", "-g"]

build.sh

@@ -5,19 +5,14 @@ set -euxo pipefail
 apk --no-cache add curl
 
 # Install dependencies
-apk --no-cache add python3 bind-tools
+apk --no-cache add python3 bind-tools bind
 
 # Get latest versions of tools using latestver
-COREDNS_VERSION=$(curl -sSfL 'https://lv.luzifer.io/catalog-api/coredns/latest.txt?p=version')
 DUMB_INIT_VERSION=$(curl -sSfL 'https://lv.luzifer.io/catalog-api/dumb-init/latest.txt?p=version')
 
-[ -z "${COREDNS_VERSION}" ] && { exit 1; }
 [ -z "${DUMB_INIT_VERSION}" ] && { exit 1; }
 
 # Install tools
-curl -sSfL https://github.com/coredns/coredns/releases/download/v${COREDNS_VERSION}/coredns_${COREDNS_VERSION}_linux_amd64.tgz | \
-  tar -x -z -C /usr/local/bin
-
 curl -sSfLo /usr/local/bin/dumb-init https://github.com/Yelp/dumb-init/releases/download/v${DUMB_INIT_VERSION}/dumb-init_${DUMB_INIT_VERSION}_amd64
 chmod +x /usr/local/bin/dumb-init
 
@@ -25,9 +20,12 @@ chmod +x /usr/local/bin/dumb-init
 pip3 install -r /src/requirements.txt
 
 # Create cron to update zones periodically
-echo "*       *       *       *       *       run-parts /etc/periodic/1min" >> /var/spool/cron/crontabs/root
+echo "*       *       *       *       *       run-parts /etc/periodic/1min" >>/var/spool/cron/crontabs/root
 mkdir -p /etc/periodic/1min
 ln -s /src/zonefile_cron /etc/periodic/1min/zonefile_cron
 
+# Link named.conf
+ln -sf /src/zones/named.conf /etc/bind/named.conf
+
 # Cleanup
 apk --no-cache del curl

docker-entrypoint.sh

@@ -1,12 +1,20 @@
 #!/usr/local/bin/dumb-init /bin/bash
 set -euxo pipefail
 
-if [ "${1:-}" = 'coredns' ]; then
-  # Start crond in the background
-  crond
+# Ensure default config without zones
+[ -e /src/zones/named.conf ] || {
+	cp /src/named.conf.default /src/zones/named.conf
+}
 
-  # Start coredns
-  exec "$@"
+if [ "${1:-}" = 'named' ]; then
+	# Generate rndc communication key
+	rndc-confgen -a
+
+	# Start crond in the background
+	crond
+
+	# Start coredns
+	exec "$@"
 fi
 
 exec "$@"

generateZonefiles.py

@@ -5,6 +5,7 @@ import difflib
 import hashlib
 import os
 import os.path
+import subprocess
 import sys
 import time
 
@@ -20,6 +21,18 @@ import yaml
 
 DEFAULT_TTL = 3600
 
+rndc_queue = []
+
+
+def call_rndc(params):
+    command = ["rndc"]
+    command.extend(params)
+
+    if 'DEBUG' in os.environ and os.environ['DEBUG'] == 'true':
+        print('DBG: Call "{}"'.format(" ".join(command)))
+    else:
+        subprocess.check_call(command, stdout=sys.stdout, stderr=sys.stderr)
+
 
 def default(d, key, default=None):
     if key in d:
@@ -41,6 +54,15 @@ def diff_files(file1, file2):
         fromlines, tolines, file1, file2)))
 
 
+def exec_rndc_queue():
+    global rndc_queue
+
+    for params in rndc_queue:
+        call_rndc(params)
+
+    rndc_queue = []
+
+
 def hash_file(filename):
     if not os.path.isfile(filename):
         return ""
@@ -55,6 +77,12 @@ def hash_file(filename):
     return hasher.hexdigest()
 
 
+def queue_rndc_call(params):
+    global rndc_queue
+
+    rndc_queue.append(params)
+
+
 def replace_soa_line(line):
     if 'SOA' in line:
         return '; SOA line replaced'
@@ -108,6 +136,25 @@ def sanitize(entry):
     return result
 
 
+def write_named_conf(zones):
+    tpl = jinja2.Template(open("named.conf").read())
+    zone_content = tpl.render({
+        "zones": zones,
+    })
+
+    with open("zones/named.conf.new", "w") as f:
+        f.write(zone_content)
+
+    if hash_file("zones/named.conf.new") != hash_file("zones/named.conf"):
+        print("Generated and replaced named.conf")
+        diff_files("zones/named.conf", "zones/named.conf.new")
+        os.rename("zones/named.conf.new", "zones/named.conf")
+
+        queue_rndc_call(['reconfig'])
+    else:
+        os.unlink("zones/named.conf.new")
+
+
 def write_zone(zone, ttl, soa, nameserver, mailserver, entries):
     soa['serial'] = int(time.time()) - 946681200  # 2000-01-01
 
@@ -128,6 +175,8 @@ def write_zone(zone, ttl, soa, nameserver, mailserver, entries):
         print("Generated and replaced zone file for {}".format(zone))
         diff_files("zones/db.{}".format(zone), "zones/tmp.{}".format(zone))
         os.rename("zones/tmp.{}".format(zone), "zones/db.{}".format(zone))
+
+        queue_rndc_call(['reload', zone])
     else:
         os.unlink("zones/tmp.{}".format(zone))
 
@@ -143,6 +192,8 @@ def main():
     consul_zones = consul.get_zones()
     zone_data['zones'] = {**consul_zones, **zone_data['zones']}
 
+    write_named_conf(zone_data['zones'].keys())
+
     for zone, config in zone_data['zones'].items():
         ttl = default(config, "default_ttl", DEFAULT_TTL)
 
@@ -161,6 +212,8 @@ def main():
         write_zone(zone, ttl, zone_data['soa'],
                    zone_data['nameserver'], mailserver, entries)
 
+    exec_rndc_queue()
+
     healthcheck()
 
 

named.conf

@@ -0,0 +1,41 @@
+include "/etc/bind/rndc.key";
+
+controls {
+      inet 127.0.0.1 port 953
+              allow { 127.0.0.1; } keys { "rndc-key"; };
+};
+
+options {
+        directory "/var/bind";
+
+        // Configure the IPs to listen on here.
+        listen-on { any; };
+        listen-on-v6 { none; };
+
+        // Specify a list of IPs/masks to allow zone transfers to here.
+        //
+        // You can override this on a per-zone basis by specifying this inside a zone
+        // block.
+        //
+        // Warning: Removing this block will cause BIND to revert to its default
+        //          behaviour of allowing zone transfers to any host (!).
+        allow-transfer {
+                none;
+        };
+
+        // If you have problems and are behind a firewall:
+        //query-source address * port 53;
+
+        pid-file "/var/run/named/named.pid";
+
+        allow-recursion { none; };
+        recursion no;
+        querylog yes;
+};
+{% for zone in zones %}
+zone "{{ zone }}" IN {
+      type master;
+      file "/src/zones/db.{{ zone }}";
+};
+{% endfor %}
+

named.conf.default

@@ -0,0 +1,34 @@
+include "/etc/bind/rndc.key";
+
+controls {
+      inet 127.0.0.1 port 953
+              allow { 127.0.0.1; } keys { "rndc-key"; };
+};
+
+options {
+        directory "/var/bind";
+
+        // Configure the IPs to listen on here.
+        listen-on { any; };
+        listen-on-v6 { none; };
+
+        // Specify a list of IPs/masks to allow zone transfers to here.
+        //
+        // You can override this on a per-zone basis by specifying this inside a zone
+        // block.
+        //
+        // Warning: Removing this block will cause BIND to revert to its default
+        //          behaviour of allowing zone transfers to any host (!).
+        allow-transfer {
+                none;
+        };
+
+        // If you have problems and are behind a firewall:
+        //query-source address * port 53;
+
+        pid-file "/var/run/named/named.pid";
+
+        allow-recursion { none; };
+        recursion no;
+        querylog yes;
+};