nginx reverse-proxy

example.conf

server {
    listen 80;
    listen [::]:80 ;
    server_name example.kongkx.com;
#  root /var/www/example;
    return 301 https://$host$request_uri;
}

server {
    listen 443 ssl http2;
    listen [::]:443 ssl http2;
    server_name example.kongkx.com;
    ssl_certificate /etc/letsencrypt/live/example.kongkx.com/cert.pem;
    ssl_certificate_key /etc/letsencrypt/live/example.kongkx.com/privkey.pem;
    access_log /var/log/nginx/example_access.log;
    # 添加 certbot challenge
    include /etc/nginx/snippets/letsencrypt-acme-challenge.conf;

    location / {
         proxy_pass http://127.0.0.1:8081;
         proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
         proxy_set_header X-Forwarded-Proto https;
         proxy_set_header Host $host;
     }
}

letsencrypt-acme-challenge.conf

#############################################################################
# Configuration file for Let's Encrypt ACME Challenge location
# This file is already included in listen_xxx.conf files.
# Do NOT include it separately!
#############################################################################
#
# This config enables to access /.well-known/acme-challenge/xxxxxxxxxxx
# on all our sites (HTTP), including all subdomains.
# This is required by ACME Challenge (webroot authentication).
# You can check that this location is working by placing ping.txt here:
# /var/www/letsencrypt/.well-known/acme-challenge/ping.txt
# And pointing your browser to:
# http://xxx.domain.tld/.well-known/acme-challenge/ping.txt
#
# Sources:
# https://community.letsencrypt.org/t/howto-easy-cert-generation-and-renewal-with-nginx/3491
#
#############################################################################

# Rule for legitimate ACME Challenge requests (like /.well-known/acme-challenge/xxxxxxxxx)
# We use ^~ here, so that we don't check other regexes (for speed-up). We actually MUST cancel
# other regex checks, because in our other config files have regex rule that denies access to files with dotted names.
location ^~ /.well-known/acme-challenge/ {

    # Set correct content type. According to this:
    # https://community.letsencrypt.org/t/using-the-webroot-domain-verification-method/1445/29
    # Current specification requires "text/plain" or no content header at all.
    # It seems that "text/plain" is a safe option.
    default_type "text/plain";

    # This directory must be the same as in /etc/letsencrypt/cli.ini
    # as "webroot-path" parameter. Also don't forget to set "authenticator" parameter
    # there to "webroot".
    # Do NOT use alias, use root! Target directory is located here:
    # /var/www/common/letsencrypt/.well-known/acme-challenge/
    root         /var/www/letsencrypt;
}

# Hide /acme-challenge subdirectory and return 404 on all requests.
# It is somewhat more secure than letting Nginx return 403.
# Ending slash is important!
location = /.well-known/acme-challenge/ {
    return 404;
}