From a0806bee086f2f90cd6a2eab50416c7cd5fa7306 Mon Sep 17 00:00:00 2001
From: Knut Ahlers <knut@ahlers.me>
Date: Tue, 6 Feb 2018 20:20:13 +0100
Subject: [PATCH] Add health check to docker container

Signed-off-by: Knut Ahlers <knut@ahlers.me>
---
 Dockerfile | 5 ++++-
 zones.yml  | 6 ++++++
 2 files changed, 10 insertions(+), 1 deletion(-)

diff --git a/Dockerfile b/Dockerfile
index 62974cf..807fd0d 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -16,7 +16,7 @@ COPY --from=0 /go/bin/coredns /usr/local/bin/
 
 ADD ./requirements.txt /src/requirements.txt
 RUN set -ex \
- && apk --no-cache add python3 \
+ && apk --no-cache add python3 bind-tools \
  && pip3 install -r /src/requirements.txt
 
 ADD . /src
@@ -26,5 +26,8 @@ EXPOSE 53/udp 53
 
 VOLUME ["/src/zones"]
 
+HEALTHCHECK --interval=30s --timeout=5s \
+  CMD dig +short @localhost health.server.test TXT || exit 1
+
 ENTRYPOINT ["/usr/local/bin/coredns"]
 CMD ["--"]
diff --git a/zones.yml b/zones.yml
index 5a7b96a..6bad0ac 100644
--- a/zones.yml
+++ b/zones.yml
@@ -354,4 +354,10 @@ zones:
       - name: ""
         alias: docker01.cloud.kserver.biz.
 
+  server.test:
+    entries:
+      - name: health
+        type: TXT
+        records:
+          - "OK"
 ...