Policy::Caching: issues when can't connect to backend.

New HTTP-NG coroutines return 0 when can't connect, so the caching
policy fails on the second request used, because the cache status was
updated with the an invalid status

This changes makes sure that the response code is a valid one, so the
caching status will report correctly.

Fix: THREESCALE-4471

Reported-by:Jakub Smadis <[email protected]>
Signed-off-by: Eloy Coto <[email protected]>

CHANGELOG.md

@@ -6,6 +6,12 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 
 ## [Unreleased]
 
+### Fixed:
+
+- Check status is bigger than zero on caching policy [THREESCALE-4471](https://issues.jboss.org/browse/THREESCALE-4471) [PR #1163](https://github.com/3scale/APIcast/pull/1163)
+
+## [3.7.0-alpha1]
+
 ### Added
 
 - Now the configuration of the issuer is cached to avoid flip-flop issues when OIDC connectivity fails. [THREESCALE-3809](https://issues.jboss.org/browse/THREESCALE-3809) [PR #1141](https://github.com/3scale/APIcast/pull/1141)

gateway/src/apicast/policy/caching/caching.lua

@@ -22,6 +22,12 @@ local _M = policy.new('Caching policy', 'builtin')
 
 local new = _M.new
 
+--- On connect issues, the status returned is 0, so need to validate that the
+--status is greater than 0 and less than 500
+local function is_valid_status(status)
+    return status and status > 0 and status < 500
+end
+
 local function strict_handler(cache, cached_key, response, ttl)
   if response.status == 200 then
     ngx.log(ngx.INFO, 'apicast cache write key: ', cached_key, ', ttl: ', ttl)
@@ -36,7 +42,7 @@ end
 local function resilient_handler(cache, cached_key, response, ttl)
   local status = response.status
 
-  if status and status < 500 then
+  if is_valid_status(status) then
     ngx.log(ngx.INFO, 'apicast cache write key: ', cached_key,
                       ' status: ', status, ', ttl: ', ttl)
 
@@ -57,7 +63,7 @@ end
 local function allow_handler(cache, cached_key, response, ttl)
   local status = response.status
 
-  if status and status < 500 then
+  if is_valid_status(status) then
     ngx.log(ngx.INFO, 'apicast cache write key: ', cached_key,
                       ' status: ', status, ', ttl: ', ttl)
 

spec/policy/caching/caching_spec.lua

@@ -78,6 +78,11 @@ describe('Caching policy', function()
         cache_handler(cache, 'a_key', { status = 500 }, nil)
         assert.equals(200, cache:get('a_key'))
       end)
+
+      it('does not cached connect issues', function()
+        cache_handler(cache, 'a_key', { status = 0 }, nil)
+        assert.equals(nil, cache:get('a_key'))
+      end)
     end)
 
     describe('when configured as allow', function()
@@ -97,6 +102,11 @@ describe('Caching policy', function()
         assert.equals(403, cache:get('a_key'))
       end)
 
+      it('does not cached connect issues', function()
+        cache_handler(cache, 'a_key', { status = 0 }, nil)
+        assert.equals(200, cache:get('a_key'))
+      end)
+
       describe('and backend returns 5XX', function()
         it('does not invalidate the cache entry if there was a 4XX', function()
           cache:set('a_key', 403)