可以用 Confd 去监控 Etcd 里某个 directory 或 keys 的改动，然后生成相当的配置文件并重新 reload 一下服务。
举个例子：将 nginx 的监听端口作为一个 key 放在 Etcd 里，当这个 key 改变时就自动 reload nginx 。
# wget https://github.com/kelseyhightower/confd/releases/download/v0.11.0/confd-0.11.0-linux-amd64
# chmod +x confd-0.11.0-linux-amd64
[template]
# The name of the template that will be used to render the application's configuration file
# Confd will look in `/etc/conf.d/templates` for these files by default
src = "nginx.tmpl"
# The location to place the rendered configuration file
dest = "/etc/nginx/conf.d/app.conf"
# The etcd keys or directory to watch. This is where the information to fill in
# the template will come from.
keys = [ "/nginx" ]
# File ownership and mode information
owner = "root"
mode = "0644"
# These are the commands that will be used to check whether the rendered config is
# valid and to reload the actual service once the new config is in place
check_cmd = "/usr/sbin/nginx -t"
reload_cmd = "/usr/sbin/service nginx reload"
server {
listen {{ getv "/nginx/port" }};
location / {
index index.html;
root /usr/share/nginx/html/;
}
}
# etcdctl set /nginx/port 8080
# ./confd-0.11.0-linux-amd64 -watch -backend etcd -node http://127.0.0.1:4001
From the first command you will see that Nginx listens on 8080.
The second command is to set the key /nginx/port to 8000.
From the third command you will see that Nginx listens on 8000.
# netstat -tnlp | grep 8080 # will show nginx listen 8080 port
# etcdctl set /nginx/port 8000
# netstat -tnlp | grep 8000 # will show nginx listen 8000 port