[PATCH 2 of 2] Upstream: allow recovery from "429 Too Many Requests" response

[Piotr Sikora]

# HG changeset patch
# User Piotr Sikora <piotrsikora at google.com>
# Date 1490348883 25200
#      Fri Mar 24 02:48:03 2017 -0700
# Node ID b377cfedf632b14a3d459e12342a0557a25a790c
# Parent  799ef976b58cadbc212bd790a666033d3777c10d
Upstream: allow recovery from "429 Too Many Requests" response.

This change adds "http_429" parameter to "proxy_next_upstream" for
retrying rate-limited requests, and to "proxy_cache_use_stale" for
serving stale cached responses after being rate-limited.

Signed-off-by: Piotr Sikora <piotrsikora at google.com>

diff -r 799ef976b58c -r b377cfedf632 src/http/modules/ngx_http_fastcgi_module.c
--- a/src/http/modules/ngx_http_fastcgi_module.c
+++ b/src/http/modules/ngx_http_fastcgi_module.c
@@ -211,6 +211,7 @@ static ngx_conf_bitmask_t  ngx_http_fast
     { ngx_string("http_503"), NGX_HTTP_UPSTREAM_FT_HTTP_503 },
     { ngx_string("http_403"), NGX_HTTP_UPSTREAM_FT_HTTP_403 },
     { ngx_string("http_404"), NGX_HTTP_UPSTREAM_FT_HTTP_404 },
+    { ngx_string("http_429"), NGX_HTTP_UPSTREAM_FT_HTTP_429 },
     { ngx_string("updating"), NGX_HTTP_UPSTREAM_FT_UPDATING },
     { ngx_string("off"), NGX_HTTP_UPSTREAM_FT_OFF },
     { ngx_null_string, 0 }
diff -r 799ef976b58c -r b377cfedf632 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
@@ -220,6 +220,7 @@ static ngx_conf_bitmask_t  ngx_http_prox
     { ngx_string("http_504"), NGX_HTTP_UPSTREAM_FT_HTTP_504 },
     { ngx_string("http_403"), NGX_HTTP_UPSTREAM_FT_HTTP_403 },
     { ngx_string("http_404"), NGX_HTTP_UPSTREAM_FT_HTTP_404 },
+    { ngx_string("http_429"), NGX_HTTP_UPSTREAM_FT_HTTP_429 },
     { ngx_string("updating"), NGX_HTTP_UPSTREAM_FT_UPDATING },
     { ngx_string("off"), NGX_HTTP_UPSTREAM_FT_OFF },
     { ngx_null_string, 0 }
diff -r 799ef976b58c -r b377cfedf632 src/http/modules/ngx_http_scgi_module.c
--- a/src/http/modules/ngx_http_scgi_module.c
+++ b/src/http/modules/ngx_http_scgi_module.c
@@ -82,6 +82,7 @@ static ngx_conf_bitmask_t ngx_http_scgi_
     { ngx_string("http_503"), NGX_HTTP_UPSTREAM_FT_HTTP_503 },
     { ngx_string("http_403"), NGX_HTTP_UPSTREAM_FT_HTTP_403 },
     { ngx_string("http_404"), NGX_HTTP_UPSTREAM_FT_HTTP_404 },
+    { ngx_string("http_429"), NGX_HTTP_UPSTREAM_FT_HTTP_429 },
     { ngx_string("updating"), NGX_HTTP_UPSTREAM_FT_UPDATING },
     { ngx_string("off"), NGX_HTTP_UPSTREAM_FT_OFF },
     { ngx_null_string, 0 }
diff -r 799ef976b58c -r b377cfedf632 src/http/modules/ngx_http_uwsgi_module.c
--- a/src/http/modules/ngx_http_uwsgi_module.c
+++ b/src/http/modules/ngx_http_uwsgi_module.c
@@ -114,6 +114,7 @@ static ngx_conf_bitmask_t ngx_http_uwsgi
     { ngx_string("http_503"), NGX_HTTP_UPSTREAM_FT_HTTP_503 },
     { ngx_string("http_403"), NGX_HTTP_UPSTREAM_FT_HTTP_403 },
     { ngx_string("http_404"), NGX_HTTP_UPSTREAM_FT_HTTP_404 },
+    { ngx_string("http_429"), NGX_HTTP_UPSTREAM_FT_HTTP_429 },
     { ngx_string("updating"), NGX_HTTP_UPSTREAM_FT_UPDATING },
     { ngx_string("off"), NGX_HTTP_UPSTREAM_FT_OFF },
     { ngx_null_string, 0 }
diff -r 799ef976b58c -r b377cfedf632 src/http/ngx_http_upstream.c
--- a/src/http/ngx_http_upstream.c
+++ b/src/http/ngx_http_upstream.c
@@ -436,6 +436,7 @@ static ngx_http_upstream_next_t  ngx_htt
     { 504, NGX_HTTP_UPSTREAM_FT_HTTP_504 },
     { 403, NGX_HTTP_UPSTREAM_FT_HTTP_403 },
     { 404, NGX_HTTP_UPSTREAM_FT_HTTP_404 },
+    { 429, NGX_HTTP_UPSTREAM_FT_HTTP_429 },
     { 0, 0 }
 };
 
@@ -4155,6 +4156,10 @@ ngx_http_upstream_next(ngx_http_request_
         status = NGX_HTTP_NOT_FOUND;
         break;
 
+    case NGX_HTTP_UPSTREAM_FT_HTTP_429:
+        status = NGX_HTTP_TOO_MANY_REQUESTS;
+        break;
+
     /*
      * NGX_HTTP_UPSTREAM_FT_BUSY_LOCK and NGX_HTTP_UPSTREAM_FT_MAX_WAITING
      * never reach here
diff -r 799ef976b58c -r b377cfedf632 src/http/ngx_http_upstream.h
--- a/src/http/ngx_http_upstream.h
+++ b/src/http/ngx_http_upstream.h
@@ -26,10 +26,11 @@
 #define NGX_HTTP_UPSTREAM_FT_HTTP_504        0x00000080
 #define NGX_HTTP_UPSTREAM_FT_HTTP_403        0x00000100
 #define NGX_HTTP_UPSTREAM_FT_HTTP_404        0x00000200
-#define NGX_HTTP_UPSTREAM_FT_UPDATING        0x00000400
-#define NGX_HTTP_UPSTREAM_FT_BUSY_LOCK       0x00000800
-#define NGX_HTTP_UPSTREAM_FT_MAX_WAITING     0x00001000
-#define NGX_HTTP_UPSTREAM_FT_NON_IDEMPOTENT  0x00002000
+#define NGX_HTTP_UPSTREAM_FT_HTTP_429        0x00000400
+#define NGX_HTTP_UPSTREAM_FT_UPDATING        0x00000800
+#define NGX_HTTP_UPSTREAM_FT_BUSY_LOCK       0x00001000
+#define NGX_HTTP_UPSTREAM_FT_MAX_WAITING     0x00002000
+#define NGX_HTTP_UPSTREAM_FT_NON_IDEMPOTENT  0x00004000
 #define NGX_HTTP_UPSTREAM_FT_NOLIVE          0x40000000
 #define NGX_HTTP_UPSTREAM_FT_OFF             0x80000000
 
@@ -38,7 +39,8 @@
                                              |NGX_HTTP_UPSTREAM_FT_HTTP_503  \
                                              |NGX_HTTP_UPSTREAM_FT_HTTP_504  \
                                              |NGX_HTTP_UPSTREAM_FT_HTTP_403  \
-                                             |NGX_HTTP_UPSTREAM_FT_HTTP_404)
+                                             |NGX_HTTP_UPSTREAM_FT_HTTP_404  \
+                                             |NGX_HTTP_UPSTREAM_FT_HTTP_429)
 
 #define NGX_HTTP_UPSTREAM_INVALID_HEADER     40