nginx反向代理location和proxy_pass的映射关系

配置nginx反向代理时，总是需要尝试多次才能配置成功，通过本文做个记录，方便以后查看。

只有主机地址的意思是，proxy_pass 值为 http://host:port 这种形式，url部分没有 / 或 /xxx 等.
对应到本文示例就是 http://backend。

这种情况下，相当于下面的公式：

backend url = proxy_pass + path

这种情况下，请求的 path 部分会直接追加到 proxy_pass 地址后，相当于把nginx地址一对一的映射到了后端地址，这种配置方式理解最简单。

location	proxy_pass	path	nginx url	backend url
/	http://backend	/	http://nginx/	http://backend/
/	http://backend	/hello	http://nginx/hello	http://backend/hello
/	http://backend	/hello/world	http://nginx/hello/world	http://backend/hello/world

location	proxy_pass	path	nginx url	backend url
/a	http://backend	/a	http://nginx/a	http://backend/a
/a	http://backend	/ab	http://nginx/ab	http://backend/ab
/a	http://backend	/a/	http://nginx/a/	http://backend/a/
/a	http://backend	/a/b	http://nginx/a/b	http://backend/a/b
/a	http://backend	/a/b/	http://nginx/a/b/	http://backend/a/b/

location	proxy_pass	path	nginx url	backend url
/b/	http://backend	/b/	http://nginx/b/	http://backend/b/
/b/	http://backend	/b/a	http://nginx/b/a	http://backend/b/a
/b/	http://backend	/b/a/	http://nginx/b/a/	http://backend/b/a/

这种情况下，相当于下面的公式：

backend url = proxy_pass + (path - location)

path 部分减去匹配的 location 部分后，剩余内容追加到 proxy_pass 上去请求。

如果不是为了 /u 去匹配 /uv 这种路径，使用 /v/ 去匹配 /v/w 这种更准确，不会出现 // 这种情况。

location	proxy_pass	path	nginx url	backend url
/u	http://backend/	/u	http://nginx/u	http://backend/
/u	http://backend/	/uv	http://nginx/uv	http://backend/v
/u	http://backend/	/u/	http://nginx/u/	http://backend//
/u	http://backend/	/u/v	http://nginx/u/v	http://backend//v
/u	http://backend/	/u/v/	http://nginx/u/v/	http://backend//v/

location	proxy_pass	path	nginx url	backend url
/v/	http://backend/	/v/	http://nginx/v/	http://backend/
/v/	http://backend/	/v/w	http://nginx/v/w	http://backend/w
/v/	http://backend/	/v/w/	http://nginx/v/w/	http://backend/w/

location	proxy_pass	path	nginx url	backend url
/c	http://backend/c	/c	http://nginx/c	http://backend/c
/c	http://backend/c	/cd	http://nginx/cd	http://backend/cd
/c	http://backend/c	/c/	http://nginx/c/	http://backend/c/
/c	http://backend/c	/c/d	http://nginx/c/d	http://backend/c/d
/c	http://backend/c	/c/d/	http://nginx/c/d/	http://backend/c/d/

location	proxy_pass	path	nginx url	backend url
/d/	http://backend/d	/d/	http://nginx/d/	http://backend/d
/d/	http://backend/d	/d/e	http://nginx/d/e	http://backend/de
/d/	http://backend/d	/d/e/	http://nginx/d/e/	http://backend/de/

location	proxy_pass	path	nginx url	backend url
/e	http://backend/e/	/e	http://nginx/e	http://backend/e/
/e	http://backend/e/	/ef	http://nginx/ef	http://backend/e/f
/e	http://backend/e/	/e/	http://nginx/e/	http://backend/e//
/e	http://backend/e/	/e/f	http://nginx/e/f	http://backend/e//f
/e	http://backend/e/	/e/f/	http://nginx/e/f/	http://backend/e//f/

location	proxy_pass	path	nginx url	backend url
/f/	http://backend/f/	/f/	http://nginx/f/	http://backend/f/
/f/	http://backend/f/	/f/g	http://nginx/f/g	http://backend/f/g
/f/	http://backend/f/	/f/g/	http://nginx/f/g/	http://backend/f/g/

location	proxy_pass	path	nginx url	backend url
/g	http://backend/m	/g	http://nginx/g	http://backend/m
/g	http://backend/m	/gh	http://nginx/gh	http://backend/mh
/g	http://backend/m	/g/	http://nginx/g/	http://backend/m/
/g	http://backend/m	/g/h	http://nginx/g/h	http://backend/m/h
/g	http://backend/m	/g/h/	http://nginx/g/h/	http://backend/m/h/

location	proxy_pass	path	nginx url	backend url
/h/	http://backend/n	/h/	http://nginx/h/	http://backend/n
/h/	http://backend/n	/h/i	http://nginx/h/i	http://backend/ni
/h/	http://backend/n	/h/i/	http://nginx/h/i/	http://backend/ni/

location	proxy_pass	path	nginx url	backend url
/i	http://backend/x/	/i	http://nginx/i	http://backend/x/
/i	http://backend/x/	/ij	http://nginx/ij	http://backend/x/j
/i	http://backend/x/	/i/	http://nginx/i/	http://backend/x//
/i	http://backend/x/	/i/j	http://nginx/i/j	http://backend/x//j
/i	http://backend/x/	/i/j/	http://nginx/i/j/	http://backend/x//j/

location	proxy_pass	path	nginx url	backend url
/j/	http://backend/y/	/j/	http://nginx/j/	http://backend/y/
/j/	http://backend/y/	/j/k	http://nginx/j/k	http://backend/y/k
/j/	http://backend/y/	/j/k/	http://nginx/j/k/	http://backend/y/k/

location	proxy_pass	path	nginx url	backend url
/ws/	http://backend/spring/ws/	/ws/qrlogin	http://nginx/ws/qrlogin	http://backend/spring/ws/qrlogin
/ws/	http://backend/spring/ws/	/ws/stomp	http://nginx/ws/stomp	http://backend/spring/ws/stomp