From 7cb58b00b54127e9bcd9544c7226b18219476d73 Mon Sep 17 00:00:00 2001
From: Florian Apolloner <florian@apolloner.eu>
Date: Mon, 28 Aug 2023 20:45:59 +0200
Subject: [PATCH] Use consul DNS inside the container to resolve
 service.consul.

---
 nomad/Dockerfile        |  7 +++++--
 nomad/consul_config.hcl |  1 +
 nomad/entrypoint.sh     | 10 ++++++++++
 3 files changed, 16 insertions(+), 2 deletions(-)
 create mode 100755 nomad/entrypoint.sh

diff --git a/nomad/Dockerfile b/nomad/Dockerfile
index 5fbb395..0eb45f0 100644
--- a/nomad/Dockerfile
+++ b/nomad/Dockerfile
@@ -124,5 +124,8 @@ COPY supervisord.conf /etc/supervisor/supervisord.conf
 VOLUME /var/lib/docker
 
 ENV JAVA_HOME=/usr/lib/jvm/openjdk PATH="/usr/lib/jvm/openjdk/bin:$PATH"
-ENTRYPOINT ["/usr/bin/supervisord"]
-CMD ["-c", "/etc/supervisor/supervisord.conf"]
+
+COPY --chmod=0755  entrypoint.sh /entrypoint.sh
+
+ENTRYPOINT ["/entrypoint.sh"]
+CMD ["/usr/bin/supervisord", "-c", "/etc/supervisor/supervisord.conf"]
diff --git a/nomad/consul_config.hcl b/nomad/consul_config.hcl
index 093ef77..62a69e7 100644
--- a/nomad/consul_config.hcl
+++ b/nomad/consul_config.hcl
@@ -9,6 +9,7 @@ advertise_addr = "{{GetInterfaceIP \"eth0\"}}"
 
 ports {
   grpc = 8502
+  dns = 53
 }
 
 connect {
diff --git a/nomad/entrypoint.sh b/nomad/entrypoint.sh
new file mode 100755
index 0000000..86df04d
--- /dev/null
+++ b/nomad/entrypoint.sh
@@ -0,0 +1,10 @@
+#!/usr/bin/env bash
+# Keep DNS intact if we are not running supervisord & as such consul
+if [[ "x$1" == "x/usr/bin/supervisord" ]]; then
+    ip addr add dev eth0 169.254.1.1
+    echo -n "recursors = " > /etc/consul.d/config/00_recursors.hcl
+    echo $(grep -E '^nameserver ' /etc/resolv.conf|cut -f 2 -d " "|jq -cnR '[inputs | select(length>0)]') >> /etc/consul.d/config/00_recursors.hcl
+    echo "$(grep -vE '^nameserver ' /etc/resolv.conf)" > /etc/resolv.conf
+    echo "nameserver 169.254.1.1" >> /etc/resolv.conf
+fi
+exec "$@"