先寫proxy不用憑證版的設定
a2a-proxy的nginx.conf如下：

user nginx;
worker_processes auto;
error_log /var/log/nginx/error.log;
pid /run/nginx.pid;

# Load dynamic modules. See /usr/share/doc/nginx/README.dynamic.
include /usr/share/nginx/modules/*.conf;

events {
    worker_connections 1024;
}

http {
    log_format  main  '$remote_addr - $remote_user [$time_local] "$request" '
                      '$status $body_bytes_sent "$http_referer" '
                      '"$http_user_agent" "$http_x_forwarded_for"';

    access_log  /var/log/nginx/access.log  main;

    sendfile            on;
    tcp_nopush          on;
    tcp_nodelay         on;
    keepalive_timeout   65;
    types_hash_max_size 4096;

    include             /etc/nginx/mime.types;
    default_type        application/octet-stream;

    # Load modular configuration files from the /etc/nginx/conf.d directory.
    # See http://nginx.org/en/docs/ngx_core_module.html#include
    # for more information.
    include /etc/nginx/conf.d/*.conf;

    server {
        listen       8443 ssl;
        server_name  _;

        ssl_certificate     /etc/nginx/certs/a2a-proxy.crt;
        ssl_certificate_key /etc/nginx/certs/a2a-proxy.key;

        ssl_protocols TLSv1.2 TLSv1.3;
        ssl_ciphers HIGH:!aNULL:!MD5;

        location ^~ /a2a/ {
            proxy_pass http://a2a-api:8081;
            proxy_http_version 1.1;

            # 在 /a2a/ 與相關 location 加入
            proxy_set_header Host $http_host;
            proxy_set_header X-Real-IP $remote_addr;
            proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
            proxy_set_header X-Forwarded-Proto $scheme;
            proxy_set_header X-Forwarded-Port $server_port;

            # 改寫後端回傳的 Location（視後端回傳 host 調整）
            proxy_redirect http://a2a-api:8081/ https://$host:8443/a2a/;

            proxy_connect_timeout 60s;
            proxy_send_timeout 60s;
            proxy_read_timeout 60s;
        }
        
        location / {
            proxy_pass http://a2a-web;
            proxy_http_version 1.1;

            proxy_set_header Host $host;
            proxy_set_header X-Real-IP $remote_addr;
            proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
            proxy_set_header X-Forwarded-Proto $scheme;

            proxy_set_header X-Forwarded-Proto https;
            proxy_set_header X-Forwarded-Port 8443;

            proxy_connect_timeout 60s;
            proxy_send_timeout 60s;
            proxy_read_timeout 60s;
        }
    }
}

ssl設定過程雖然複雜，但網路也有不少相同主題的文章可參考。這個留到明天講。
主要有兩點：
1.proxy_pass：在location根目錄設定是：proxy_pass http://a2a-web，容器中透過同個NetworkName設定(即a2a-net)可以導向ContainerName:ContainerPort。如以下a2a-web.container的設定，導向預設80 port：

ContainerName=a2a-web
PublishPort=8080:80

2.proxy_redirect：在location /a2a/目錄設定是：

proxy_pass http://a2a-api:8081;
# 改寫後端回傳的 Location（視後端回傳 host 調整）
proxy_redirect http://a2a-api:8081/ https://$host:8443/a2a/;

這裡proxy_redirect的設定就符合昨天講的，以下我描述更詳細點：

F5 -> a2a-proxy:8443 -> a2a-web:80 -> a2a-proxy:8081/a2a -> a2a-api:8081/a2a

在前端的a2a-web呼叫後端的a2a-api時，URI都是/a2a，所以前端程式呼叫a2a-api，可以a2a-api:8081/a2a或a2a-proxy:8081/a2a ，這兩者是等值的。

從瀏覽器呼叫不經過F5：
https://RedHatIP:8443 會被a2a-proxy:8443 導向a2a-web:80
https://RedHatIP:8443/a2a 會被a2a-proxy:8443/a2a 導向a2a-api:8081