EMQ X 在支持客户的过程中，了解到有客户使用 Nginx 做负载均衡，Docker 容器手动加入集群的方式运行 EMQ 集群，现将主要过程记录下来。
业务需求
- 使用 Nginx 作为反向代理
- Nginx 需要提前分配好代理 server 的地址
- 使用 Docker 容器运行 EMQ
- EMQ 自动重启
- EMQ 重启后自动集群
$ cat /etc/nginx/tcpstream.conf## tcp LB and SSL passthrough for backend ##stream { upstream mqtt_broker { server 127.0.0.1:21871; #max_fails=5 fail_timeout=30s; server 127.0.0.1:21872; #max_fails=5 fail_timeout=30s; server 127.0.0.1:21873; #max_fails=5 fail_timeout=30s; server 127.0.0.1:21874; #max_fails=5 fail_timeout=30s; server 127.0.0.1:21875; #max_fails=5 fail_timeout=30s; server 127.0.0.1:21881; #max_fails=5 fail_timeout=30s; server 127.0.0.1:21891; #max_fails=5 fail_timeout=30s; server 127.0.0.1:21882; #max_fails=5 fail_timeout=30s; server 127.0.0.1:21892; #max_fails=5 fail_timeout=30s; server 127.0.0.1:21883; #max_fails=5 fail_timeout=30s; server 127.0.0.1:21893; #max_fails=5 fail_timeout=30s; server 127.0.0.1:21884; #max_fails=5 fail_timeout=30s; server 127.0.0.1:21894; #max_fails=5 fail_timeout=30s; server 127.0.0.1:21885; #max_fails=5 fail_timeout=30s; server 127.0.0.1:21895; #max_fails=5 fail_timeout=30s; } log_format basic '$proxy_protocol_addr - $remote_addr [$time_local] ' '$protocol $status $bytes_sent $bytes_received ' '$session_time "$upstream_addr" ' '"$upstream_bytes_sent" "$upstream_bytes_received" "$upstream_connect_time"'; access_log /var/log/nginx/access.log basic; error_log /var/log/nginx/error.log; server { listen 8884 ssl; # proxy_protocol; proxy_next_upstream on; #proxy_bind $remote_addr transparent; proxy_ssl off; proxy_pass mqtt_broker; proxy_protocol on; #ssl_on; # adding some extra proxy settings proxy_timeout 350s; #proxy_buffer_size 128k; #ssl_certificate /etc/nginx/certs/solace.pem; #ssl_certificate_key /etc/nginx/certs/solace.pem; ssl_certificate /etc/nginx/certs/cert.pem; ssl_certificate_key /etc/nginx/certs/key.pem; #ssl_verify_client off; ssl_protocols TLSv1 TLSv1.1 TLSv1.2; ssl_ciphers HIGH:!aNULL:!MD5; } }客户自行编译的 Docker image，并非使用 EMQ 提供的官方镜像。
Dockerfile 目录如下：
$ ll /opt/Docker/总用量 28 -rw-r--r-- 1 alexeyp emq 620 10月 22 17:26 Dockerfile lrwxrwxrwx 1 alexeyp emq 13 10月 24 13:59 emqttd -> emqttd.2.3.11 drwxr-xr-x 10 alexeyp emq 110 10月 24 14:27 emqttd.2.3.11 -rwxr-xr-x 1 alexeyp emq 3463 10月 26 05:03 StartEmqInstance.sh -rwxr-xr-x 1 alexeyp alexeyp 270 10月 25 10:46 status.shDockerfile:
$ cat DockerfileFROM centos:latest RUN yum -y update EXPOSE 60000-65000 WORKDIR /opt/emqttd ADD ./emqttd /opt/emqttd ADD ./vsparc.rpm /tmp/vsparc.rpm ADD ./StartEmqInstance.sh /opt/emqttd/StartEmqInstance.sh RUN yum install -y epel-release RUN yum install -y which less sed net-tools telnet gtest /tmp/vsparc.rpm ENV TZ Australia/Melbourne CMD bash /opt/emqttd/StartEmqInstance.sh && bash可以看到 Docker 容器启动后会执行一个 StartEmqInstance.sh 的脚本，查看该脚本:
$ cat StartEmqInstance.sh#!/bin/bashDIR=$(dirname $0) HOSTNAME=$(hostname -s) function adjust_instance() { local INST=$1 local INST_ROOT=$2 cat $INST_ROOT/etc/emq.conf | \ sed -re "s/^node\.name\s*=.*$/node.name = emq$INST@127.0.0.1/" | \ #sed -re "s/^cluster\.name\s*=.*$/cluster.name = $HOSTNAME/" | \ sed -re "s/^listener\.tcp\.external\s*=.*$/listener.tcp.external = 0.0.0.0:6188$INST/" | \ sed -re "s/^listener\.tcp\.external1\s*=.*$/listener.tcp.external1 = 0.0.0.0:6189$INST/" | \ sed -re "s/^listener\.tcp\.external2\s*=.*$/listener.tcp.external2 = 0.0.0.0:6187$INST/" | \ sed -re "s/^listener\.tcp\.internal\s*=.*$/listener.tcp.internal = 127.0.0.1:6298$INST/" | \ sed -re "s/^listener\.ssl\.external\s*=.*$/listener.ssl.external = 6288$INST/" | \ sed -re "s/^listener\.ws\.external\s*=.*$/listener.ws.external = 6208$INST/" | \ sed -re "s/^listener\.wss\.external\s*=.*$/listener.ws.external = 6308$INST/" | \ sed -re "s/^listener\.api\.mgmt\s*=.*$/listener.api.mgmt = 6408$INST/" | \ sed -re "s/^(##\s)?listener\.tcp\.external\.proxy_protocol\s=.*$/listener.tcp.external.proxy_protocol = on/" | \ sed -re "s/^(##\s)?listener\.tcp\.external1\.proxy_protocol\s=.*$/listener.tcp.external1.proxy_protocol = on/" | \ sed -re "s/^(##\s)?listener\.tcp\.external2\.proxy_protocol\s=.*$/listener.tcp.external2.proxy_protocol = on/" | \ sed -re "s/^(##\s)?listener\.tcp\.external\.proxy_protocol_timeout\s=.*$/listener.tcp.external.proxy_protocol_timeout = 30s/" | \ sed -re "s/^(##\s)?listener\.tcp\.external1\.proxy_protocol_timeout\s=.*$/listener.tcp.external1.proxy_protocol_timeout = 30s/" | \ sed -re "s/^(##\s)?listener\.tcp\.external2\.proxy_protocol_timeout\s=.*$/listener.tcp.external2.proxy_protocol_timeout = 30s/" | \ sed -re "s/^(##\s)?node.dist_listen_min\s*=.*$/node.dist_listen_min = 6000$INST/" | \ sed -re "s/^(##\s)?node.dist_listen_max\s*=.*$/node.dist_listen_max = 6000$INST/" | \ cat - > $INST_ROOT/etc/emq.conf.new mv $INST_ROOT/etc/emq.conf.new $INST_ROOT/etc/emq.conf } function cluster_instance() { local INST=$1 for DEST in 1 2 3 4 5; do if [ $DEST == $INST ]; then continue; fi DEST_NODE="emq$DEST@127.0.0.1" RESULT=$(/opt/emqttd/bin/emqttd_ctl cluster join $DEST_NODE 2>&1) echo "$RESULT" echo "$RESULT" | grep -E 'successfully|already' > /dev/null RC=$? [ $RC == 0 ] && break done } cd "$DIR" if [ "$EMQ_INSTANCE_NUMBER" == "" ]; then echo "Environment variable EMQ_INSTANCE_NUMBER(1..10) is not set." echo "eMQ instance name is not configured." exit 1 else adjust_instance $EMQ_INSTANCE_NUMBER $DIR fi function run_application() { local CMD="$1" local RC=1 while [ $RC != 0 ]; do $CMD RC=$? echo "### Exited: $CMD" echo "### rc = $RC" #[ $RC != 0 ] && sleep 3 RC=1 done echo "### Done: $CMD" } function start_node() { bin/emqttd start STARTED=0 while [ $STARTED == 0 ]; do sleep 1 /opt/emqttd/bin/emqttd_ctl status | grep "is running" [ $? == 0 ] && break done cluster_instance $EMQ_INSTANCE_NUMBER > /tmp/cluster_instance.log } start_node sleep 5 run_application "/usr/local/bin/emqtt-stats-collector" &#waitIDLE_TIME=0 while [[ $IDLE_TIME -lt 5 ]] do IDLE_TIME=$((IDLE_TIME+1)) if [[ ! -z "$( /opt/emqttd/bin/emqttd_ctl status|grep 'is running'|awk '{print $1}')" ]]; then IDLE_TIME=0 else echo "['$(date -u +"%Y-%m-%dT%H:%M:%SZ")']:emqttd not running, waiting for recovery in $((60-IDLE_TIME*5)) seconds" fi sleep 5 done echo "['$(date -u +"%Y-%m-%dT%H:%M:%SZ")']:emqttd exit abnormally" exit 1脚本内容稍多而且有些复杂，需要结合 start.sh 脚本和 etc/emq.conf一起看
$ cat start.sh#!/bin/bashfor INST in 1 2 3 4 5 do docker ps | grep -E "\sinstance_$INST$" if [ $? != 0 ]; then #docker run -itd ---ulimit nofile=1048576 -restart=always -v /opt/Docker/emqtt/emq$INST/data/mnesia:/opt/emqttd/data/mnesia -e EMQ_INSTANCE_NUMBER=$INST --name=instance_$INST --network host emq:test & docker run -itd --ulimit nofile=1048576 -e EMQ_INSTANCE_NUMBER=$INST --name=instance_$INST --network host emq:latest & fi done waitetc/emq.conf`的全文就不贴出来了，主要是增加了两个 tcp 监听端口，并且关闭了`listener.tcp.external.tune_buffer $ cat etc/emq.conf...... ##-------------------------------------------------------------------- listener.tcp.external = 0.0.0.0:21881 listener.tcp.external.acceptors = 16 listener.tcp.external.max_clients = 512000 listener.tcp.external.access.1 = allow all listener.tcp.external.proxy_protocol = on listener.tcp.external.proxy_protocol_timeout = 30s listener.tcp.external.backlog = 1024 listener.tcp.external.send_timeout = 15s listener.tcp.external.send_timeout_close = on ## listener.tcp.external.tune_buffer = on listener.tcp.external.nodelay = true listener.tcp.external.reuseaddr = true ##-------------------------------------------------------------------- listener.tcp.external1 = 0.0.0.0:21891 listener.tcp.external1.acceptors = 16 listener.tcp.external1.max_clients = 512000 listener.tcp.external1.access.1 = allow all listener.tcp.external1.proxy_protocol = on listener.tcp.external1.proxy_protocol_timeout = 30s listener.tcp.external1.backlog = 1024 listener.tcp.external1.send_timeout = 15s listener.tcp.external1.send_timeout_close = on ## listener.tcp.external1.tune_buffer = on listener.tcp.external1.nodelay = true listener.tcp.external1.reuseaddr = true ##-------------------------------------------------------------------- listener.tcp.external2 = 0.0.0.0:21871 listener.tcp.external2.acceptors = 16 listener.tcp.external2.max_clients = 512000 listener.tcp.external2.access.1 = allow all listener.tcp.external2.proxy_protocol = on listener.tcp.external2.proxy_protocol_timeout = 30s listener.tcp.external2.backlog = 1024 listener.tcp.external2.send_timeout = 15s listener.tcp.external2.send_timeout_close = on ## listener.tcp.external2.tune_buffer = on listener.tcp.external2.nodelay = true listener.tcp.external2.reuseaddr = true ......业务分析
Docker 容器创建之后，StartEmqInstance.sh执行adjust_instance()将etc/emq.conf中监听的端口修改为Nginx 的代理 server
sed -re "s/^node\.name\s*=.*$/node.name = emq$INST@127.0.0.1/" | \ sed -re "s/^listener\.tcp\.external\s*=.*$/listener.tcp.external = 0.0.0.0:6188$INST/" sed -re "s/^listener\.tcp\.external1\s*=.*$/listener.tcp.external1 = 0.0.0.0:6189$INST/" sed -re "s/^listener\.tcp\.external2\s*=.*$/listener.tcp.external2 = 0.0.0.0:6187$INST/" sed -re "s/^listener\.tcp\.internal\s*=.*$/listener.tcp.internal = 127.0.0.1:6298$INST/" 并通过 join 命令来实现集群功能
function cluster_instance() { local INST=$1 for DEST in 1 2 3 4 5; do if [ $DEST == $INST ]; then continue; fi DEST_NODE="emq$DEST@127.0.0.1" RESULT=$(/opt/emqttd/bin/emqttd_ctl cluster join $DEST_NODE 2>&1) echo "$RESULT" echo "$RESULT" | grep -E 'successfully|already' > /dev/null RC=$? [ $RC == 0 ] && break done }循环检查 EMQ 的状态，当 EMQ 停止了之后退出容器
IDLE_TIME=0 while [[ $IDLE_TIME -lt 5 ]] do IDLE_TIME=$((IDLE_TIME+1)) if [[ ! -z "$( /opt/emqttd/bin/emqttd_ctl status|grep 'is running'|awk '{print $1}')" ]]; then IDLE_TIME=0 else echo "['$(date -u +"%Y-%m-%dT%H:%M:%SZ")']:emqttd not running, waiting for recovery in $((60-IDLE_TIME*5)) seconds" fi sleep 5 done echo "['$(date -u +"%Y-%m-%dT%H:%M:%SZ")']:emqttd exit abnormally" exit 1客户端通过 SSL 方式连接 <Nginx IP:8884> 地址，Nginx 将连接以 TCP 方式负载到 EMQ 节点。
PS：关于 Nginx 如何反向代理 tcp 和 ssl 的设置，可以参考 EMQ X 消息服务器 Nginx 反向代理
容器启动后通过StartEmqInstance.sh脚本查询 EMQ 的状态，当 EMQ 停止时退出容器，配合--restart=always来达到重启容器的目的。
EMQ 将集群信息储存在data/mnesia中，将容器的中的目录映射到宿主机，当容器重启之后会读取宿主机映射的相关目录，实现重启后自动集群。
存在问题
- Docker 的 host 网络模式使用宿主机的网络，当宿主机有其他业务在执行的时候，容易出现端口冲突
解决方案
- 修改
/proc/sys/net/ipv4/ip_local_port_range指定系统分配的端口为1024 60000，然后将 EMQ 的业务端口分配为 60000 之后的端口
实践案例
建议使用 kubernetes 来编排 docker 容器：
- EMQ 可以通过
kube-apiserver来实现自动集群的功能。 - 该客户目前只是在单机部署docker集群，使用 kubernetes 可以轻易实现多个节点之间部署集群。
- kubernetes 的
deployment可以监控emqx pod的状态，实现自动重启、弹性扩容等功能。 - 每个
emqx pod都有独立的虚拟 IP，不会出现端口冲突的问题。 - kubernetes 的
Service可以实现固定 IP 和负载均衡的需求，在Service创建的请求中，可以通过设置spec.clusterIP字段来指定自己的集群 IP 地址，将 Nginx 的代理 server 设置成clusterIP即可，Service可自行实现负载均衡。
原文链接：https://segmentfault.com/a/1190000019960329
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