fix(rate-limiting): do not set response headers if conf.hide_client_headers is true

.gitignore

@@ -31,8 +31,6 @@ bin/grpcurl
 *.bak
 *.rock
 
-bazel-*
-
 worktree/
 bin/bazel
 bin/h2client
@@ -41,3 +39,8 @@ bin/h2client
 *.wasm
 spec/fixtures/proxy_wasm_filters/build
 spec/fixtures/proxy_wasm_filters/target
+
+# bazel
+bazel-*
+# remove it after migrating from WORKSPACE to Bzlmod
+MODULE.bazel.lock

changelog/unreleased/kong/fix-rl-plugin-resp-hdr.yml

@@ -0,0 +1,6 @@
+message: >
+  **Rate-Limiting**: Fixed an issue that caused an
+  HTTP 500 error when `hide_client_headers`
+  is set to `true` and the request exceeds the rate limit.
+type: bugfix
+scope: Plugin

kong/plugins/rate-limiting/handler.lua

@@ -192,12 +192,17 @@ function RateLimitingHandler:access(conf)
 
     -- If limit is exceeded, terminate the request
     if stop then
-      pdk_rl_store_response_header(ngx_ctx, RETRY_AFTER, reset)
-      pdk_rl_apply_response_headers(ngx_ctx)
+      if not conf.hide_client_headers then
+        pdk_rl_store_response_header(ngx_ctx, RETRY_AFTER, reset)
+        pdk_rl_apply_response_headers(ngx_ctx)
+      end
+
       return kong.response.error(conf.error_code, conf.error_message)
     end
 
-    pdk_rl_apply_response_headers(ngx_ctx)
+    if not conf.hide_client_headers then
+      pdk_rl_apply_response_headers(ngx_ctx)
+    end
   end
 
   if conf.sync_rate ~= SYNC_RATE_REALTIME and conf.policy == "redis" then

spec/03-plugins/23-rate-limiting/04-access_spec.lua

@@ -650,7 +650,22 @@ if limit_by == "ip" then
     })
 
     local res = assert(GET(test_path))
+    assert.res_status(200, res)
+
+    assert.is_nil(res.headers["X-Ratelimit-Limit-Minute"])
+    assert.is_nil(res.headers["X-Ratelimit-Remaining-Minute"])
+    assert.is_nil(res.headers["Ratelimit-Limit"])
+    assert.is_nil(res.headers["Ratelimit-Remaining"])
+    assert.is_nil(res.headers["Ratelimit-Reset"])
+    assert.is_nil(res.headers["Retry-After"])
+
+    -- repeat until get rate-limited
+    helpers.wait_until(function()
+      res = assert(GET(test_path))
+      return res.status == 429, "should be rate-limited (429), got " .. res.status
+    end, 10)
 
+    assert.res_status(429, res)
     assert.is_nil(res.headers["X-Ratelimit-Limit-Minute"])
     assert.is_nil(res.headers["X-Ratelimit-Remaining-Minute"])
     assert.is_nil(res.headers["Ratelimit-Limit"])