# HG changeset patch
# User Roman Arutyunyan <arut@nginx.com>
# Date 1447246050 -10800
# Node ID 4d5ac1a31d4430f221790545037e201a3aba75b4
# Parent  909b5b191f25d0f9e03667a10d23f6ef27d014a3
Upstream: proxy_cache_convert_head directive.

The directive toggles conversion of HEAD to GET for cacheable proxy requests.
When disabled, $request_method must be added to cache key for consistency.
By default, HEAD is converted to GET as before.

diff --git a/src/http/modules/ngx_http_proxy_module.c b/src/http/modules/ngx_http_proxy_module.c
--- a/src/http/modules/ngx_http_proxy_module.c
+++ b/src/http/modules/ngx_http_proxy_module.c
@@ -533,6 +533,13 @@ static ngx_command_t  ngx_http_proxy_com
       offsetof(ngx_http_proxy_loc_conf_t, upstream.cache_revalidate),
       NULL },
 
+    { ngx_string("proxy_cache_convert_head"),
+      NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_HTTP_LOC_CONF|NGX_CONF_FLAG,
+      ngx_conf_set_flag_slot,
+      NGX_HTTP_LOC_CONF_OFFSET,
+      offsetof(ngx_http_proxy_loc_conf_t, upstream.cache_convert_head),
+      NULL },
+
 #endif
 
     { ngx_string("proxy_temp_path"),
@@ -2845,6 +2852,7 @@ ngx_http_proxy_create_loc_conf(ngx_conf_
     conf->upstream.cache_lock_timeout = NGX_CONF_UNSET_MSEC;
     conf->upstream.cache_lock_age = NGX_CONF_UNSET_MSEC;
     conf->upstream.cache_revalidate = NGX_CONF_UNSET;
+    conf->upstream.cache_convert_head = NGX_CONF_UNSET;
 #endif
 
     conf->upstream.hide_headers = NGX_CONF_UNSET_PTR;
@@ -3143,6 +3151,9 @@ ngx_http_proxy_merge_loc_conf(ngx_conf_t
     ngx_conf_merge_value(conf->upstream.cache_revalidate,
                               prev->upstream.cache_revalidate, 0);
 
+    ngx_conf_merge_value(conf->upstream.cache_convert_head,
+                              prev->upstream.cache_convert_head, 1);
+
 #endif
 
     ngx_conf_merge_str_value(conf->method, prev->method, "");
diff --git a/src/http/ngx_http_upstream.c b/src/http/ngx_http_upstream.c
--- a/src/http/ngx_http_upstream.c
+++ b/src/http/ngx_http_upstream.c
@@ -764,7 +764,7 @@ ngx_http_upstream_cache(ngx_http_request
             return rc;
         }
 
-        if (r->method & NGX_HTTP_HEAD) {
+        if ((r->method & NGX_HTTP_HEAD) && u->conf->cache_convert_head) {
             u->method = ngx_http_core_get_method;
         }
 
diff --git a/src/http/ngx_http_upstream.h b/src/http/ngx_http_upstream.h
--- a/src/http/ngx_http_upstream.h
+++ b/src/http/ngx_http_upstream.h
@@ -193,6 +193,7 @@ typedef struct {
     ngx_msec_t                       cache_lock_age;
 
     ngx_flag_t                       cache_revalidate;
+    ngx_flag_t                       cache_convert_head;
 
     ngx_array_t                     *cache_valid;
     ngx_array_t                     *cache_bypass;