问在openresty中，我可以在ssl_certificate_by_lua_block之前运行哪个指令来获取用户代理信息

EN

2022/06/13 09:20:58 [error] 31918#31918: *18 lua entry thread aborted: runtime error: ssl_client_hello_by_lua:6: API disabled in the current context
stack traceback:
coroutine 0:
    [C]: in function 'error'
    /usr/local/openresty/lualib/resty/core/request.lua:140: in function 'get_headers'
    ssl_client_hello_by_lua:6: in main chunk, context: ssl_client_hello_by_lua*, client: 1.2.3.4, server: 0.0.0.0:443

# HTTPS server
server {
    listen 443 ssl;

    rewrite_by_lua_block {
        local user_agent = ngx.req.get_headers()["user-agent"]
        ngx.log(ngx.ERR, "rewrite_by_lua_block user_agent -- > ", user_agent)
    }

    ssl_client_hello_by_lua_block {
        ngx.log(ngx.ERR, "I am from ssl_client_hello_by_lua_block")
        local ssl_clt = require "ngx.ssl.clienthello"
        local host, err = ssl_clt.get_client_hello_server_name()
        ngx.log(ngx.ERR, "hosts -- > ", host)
        -- local user_agent = ngx.req.get_headers()["user-agent"]
        -- ngx.log(ngx.ERR, "user_agent -- > ", user_agent)
    }

    ssl_certificate_by_lua_block {
      auto_ssl:ssl_certificate()
    }
    ssl_certificate /etc/ssl/resty-auto-ssl-fallback.crt;
    ssl_certificate_key /etc/ssl/resty-auto-ssl-fallback.key;
    location / {
    proxy_pass http://backend_proxy$request_uri;
  }
}