Nginx 反代后端证书配置问题

使用 docker 启动了 elasticsearch 8.0 ，因为这个版本的 es 是使用 https 请求的，所以 curl 测试的时候要带上自签证书

curl --cacert http_ca.crt -u elastic:elastic123 https://127.0.0.1:9200

想暴露一部分接口给公网访问，就用 nginx 反代，nginx 的域名已经使用了 acme 签发的证书，前面我还在想 nginx 怎么配置 localtion /es/ 那部分的证书，大概参考了这个文档：

https://docs.nginx.com/nginx/admin-guide/security-controls/securing-http-traffic-upstream/

但实际上，反代之后，请求 https://reverse.com/es/ 的域名，location /es/ {} 下不用配置 elasticsearch 自签的证书都可以，这个是什么原理？


  location /es/ {
     proxy_pass https://127.0.0.1:9200/;
     include proxy.conf;
  }

本地不带证书请求会错误
curl -u elastic:elastic123 https://127.0.0.1:9200
curl: (60) SSL certificate problem: self signed certificate in certificate chain
More details here: https://curl.haxx.se/docs/sslcerts.html

curl failed to verify the legitimacy of the server and therefore could not
establish a secure connection to it. To learn more about this situation and
how to fix it, please visit the web page mentioned above.


请求反代的域名直接可以

curl -u elastic:elastic123 https://reverse.com/es/
{
  "name" : "xx",
  "cluster_name" : "docker-cluster",
  "cluster_uuid" : "xx",
  "version" : {
    "number" : "8.2.3",
    "build_flavor" : "default",
    "build_type" : "docker",
    "build_hash" : "xx",
    "build_date" : "xx",
    "build_snapshot" : false,
    "lucene_version" : "9.1.0",
    "minimum_wire_compatibility_version" : "7.17.0",
    "minimum_index_compatibility_version" : "7.0.0"
  },
  "tagline" : "You Know, for Search"
}