test: add a script to test dns cluster node discovery

apps/emqx/rebar.config

@@ -27,7 +27,7 @@
     {jiffy, {git, "https://github.com/emqx/jiffy", {tag, "1.0.5"}}},
     {cowboy, {git, "https://github.com/emqx/cowboy", {tag, "2.9.0"}}},
     {esockd, {git, "https://github.com/emqx/esockd", {tag, "5.9.3"}}},
-    {ekka, {git, "https://github.com/emqx/ekka", {tag, "0.12.9"}}},
+    {ekka, {git, "https://github.com/emqx/ekka", {tag, "0.13.0"}}},
     {gen_rpc, {git, "https://github.com/emqx/gen_rpc", {tag, "2.8.1"}}},
     {hocon, {git, "https://github.com/emqx/hocon.git", {tag, "0.28.2"}}},
     {pbkdf2, {git, "https://github.com/emqx/erlang-pbkdf2.git", {tag, "2.0.4"}}},

apps/emqx_conf/i18n/emqx_conf_schema.conf

@@ -342,7 +342,7 @@ It is refreshed automatically, as long as the node is alive.
   cluster_k8s_address_type {
     desc {
       en: """Address type used for connecting to the discovered nodes.
-setting <code>cluster.k8s.address_type</code> to <code>ip</code> will
+Setting <code>cluster.k8s.address_type</code> to <code>ip</code> will
 make EMQX to discover IP addresses of peer nodes from Kubernetes API.
 """
       zh: """当使用 k8s 方式集群时，address_type 用来从 Kubernetes 接口的应答里获取什么形式的 Host 列表。

apps/emqx_conf/src/emqx_conf_schema.erl

@@ -287,7 +287,7 @@ fields(cluster_dns) ->
                     desc => ?DESC(cluster_dns_name),
                     'readOnly' => true
                 }
-            )},
+            )}
     ];
 fields(cluster_etcd) ->
     [

scripts/make-docker-image-from-host-build.sh

@@ -22,7 +22,8 @@ if [ "$COMPILE" = '--compile' ]; then
     sync
 fi
 
-export DOCKER_BUILDKIT=1
+# cannot enable DOCKER_BUILDKIT because the COPY often gets stale layers
+#export DOCKER_BUILDKIT=1
 docker build --build-arg PROFILE="${PROFILE}" \
     -t "emqx/emqx:${PKG_VSN}-${DISTRO}" \
     -f "$EMQX_DOCKERFILE" .

scripts/test-node-discovery-dns.sh

@@ -0,0 +1,77 @@
+#!/usr/bin/env bash
+
+## Test two nodes-cluster discover each other using DNS A records lookup result.
+
+set -euo pipefail
+
+cd -P -- "$(dirname -- "$0")/.."
+
+IMAGE="${1}"
+
+NET='test_node_discovery_dns'
+NODE1='emqx1'
+NODE2='emqx2'
+COOKIE='this-is-a-secret'
+
+# cleanup
+docker rm -f dnsmasq >/dev/null 2>&1 || true
+docker rm -f "$NODE1" >/dev/null 2>&1 || true
+docker rm -f "$NODE2" >/dev/null 2>&1 || true
+docker network rm "$NET" >/dev/null 2>&1 || true
+
+docker network create --subnet=172.18.0.0/16 $NET
+
+IP0="172.18.0.100"
+IP1="172.18.0.101"
+IP2="172.18.0.102"
+DOMAIN="dnstest.mynet"
+
+# create configs for dnsmasq
+cat <<-EOF > "/tmp/dnsmasq.conf"
+conf-dir=/etc/dnsmasq,*.conf
+addn-hosts=/etc/hosts.$DOMAIN
+EOF
+
+cat <<-EOF > "/tmp/hosts.$DOMAIN"
+$IP1 $DOMAIN
+$IP2 $DOMAIN
+EOF
+
+cat <<-EOF > /tmp/dnsmasq.base.conf
+domain-needed
+bogus-priv
+no-hosts
+keep-in-foreground
+no-resolv
+expand-hosts
+server=8.8.8.8
+EOF
+
+docker run -d -t --name dnsmasq \
+    --net "$NET" \
+    --ip "$IP0" \
+    -v /tmp/dnsmasq.conf:/etc/dnsmasq.conf \
+    -v "/tmp/hosts.$DOMAIN:/etc/hosts.$DOMAIN" \
+    -v "/tmp/dnsmasq.base.conf:/etc/dnsmasq/0.base.conf" \
+    --cap-add=NET_ADMIN \
+    storytel/dnsmasq dnsmasq --no-daemon --log-queries
+
+start_emqx() {
+    NAME="$1"
+    IP="$2"
+    DASHBOARD_PORT="$3"
+    docker run -d -t \
+        --name "$NAME" \
+        --net "$NET" \
+        --ip "$IP" \
+        --dns "$IP0" \
+        -p "$DASHBOARD_PORT:18083" \
+        -e EMQX_LOG__CONSOLE_HANDLER__LEVEL=debug \
+        -e EMQX_NODE_COOKIE="$COOKIE" \
+        -e EMQX_cluster__discovery_strategy='dns' \
+        -e EMQX_cluster__dns__name="$DOMAIN" \
+        "$IMAGE"
+}
+
+start_emqx "$NODE1" "$IP1" 18083
+start_emqx "$NODE2" "$IP2" 18084