proxy_cache_key
diff --git a/src/http/modules/ngx_http_proxy_module.c b/src/http/modules/ngx_http_proxy_module.c
index 1338476..f469665 100644
--- a/src/http/modules/ngx_http_proxy_module.c
+++ b/src/http/modules/ngx_http_proxy_module.c
@@ -64,6 +64,10 @@
     ngx_str_t                      location;
     ngx_str_t                      url;
 
+#if (NGX_HTTP_CACHE)
+    ngx_http_complex_value_t       cache_key;
+#endif
+
     ngx_http_proxy_vars_t          vars;
 
     ngx_flag_t                     redirect;
@@ -132,6 +136,8 @@
 #if (NGX_HTTP_CACHE)
 static char *ngx_http_proxy_cache(ngx_conf_t *cf, ngx_command_t *cmd,
     void *conf);
+static char *ngx_http_proxy_cache_key(ngx_conf_t *cf, ngx_command_t *cmd,
+    void *conf);
 #endif
 
 static char *ngx_http_proxy_lowat_check(ngx_conf_t *cf, void *post, void *data);
@@ -327,6 +333,13 @@
       0,
       NULL },
 
+    { ngx_string("proxy_cache_key"),
+      NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_HTTP_LOC_CONF|NGX_CONF_FLAG,
+      ngx_http_proxy_cache_key,
+      NGX_HTTP_LOC_CONF_OFFSET,
+      0,
+      NULL },
+
     { ngx_string("proxy_cache_path"),
       NGX_HTTP_MAIN_CONF|NGX_CONF_2MORE,
       ngx_http_file_cache_set_slot,
@@ -715,6 +728,15 @@
         return NGX_ERROR;
     }
 
+    if (plcf->cache_key.value.len) {
+
+        if (ngx_http_complex_value(r, &plcf->cache_key, key) != NGX_OK) {
+            return NGX_ERROR;
+        }
+
+        return NGX_OK;
+    }
+
     *key = ctx->vars.key_start;
 
     key = ngx_array_push(&r->cache->keys);
@@ -2068,6 +2090,10 @@
     ngx_conf_merge_ptr_value(conf->upstream.cache_valid,
                              prev->upstream.cache_valid, NULL);
 
+    if (conf->cache_key.value.data == NULL) {
+        conf->cache_key = prev->cache_key;
+    }
+
 #endif
 
     if (conf->method.len == 0) {
@@ -2738,6 +2764,34 @@
     return NGX_CONF_OK;
 }
 
+
+static char *
+ngx_http_proxy_cache_key(ngx_conf_t *cf, ngx_command_t *cmd, void *conf)
+{
+    ngx_http_proxy_loc_conf_t *plcf = conf;
+
+    ngx_str_t                         *value;
+    ngx_http_compile_complex_value_t   ccv;
+
+    value = cf->args->elts;
+
+    if (plcf->cache_key.value.len) {
+        return "is duplicate";
+    }
+
+    ngx_memzero(&ccv, sizeof(ngx_http_compile_complex_value_t));
+
+    ccv.cf = cf;
+    ccv.value = &value[1];
+    ccv.complex_value = &plcf->cache_key;
+
+    if (ngx_http_compile_complex_value(&ccv) != NGX_OK) {
+        return NGX_CONF_ERROR;
+    }
+
+    return NGX_CONF_OK;
+}
+
 #endif