fix(proxy-cache): changes age param (#12812)

The age parameter on the schema was in lower case which caused
the header Age to appear only when the kong debug option was enabled.
This commit changes the schema parameter from age to Age.

Fixes: #12787

changelog/unreleased/kong/fix-age-header.yml

@@ -0,0 +1,3 @@
+message: "proxy-cache response_headers age schema parameter changed from age to Age."
+type: bugfix
+scope: "Plugin"

kong-3.8.0-0.rockspec

@@ -538,6 +538,7 @@ build = {
     ["kong.plugins.proxy-cache.api"]                  = "kong/plugins/proxy-cache/api.lua",
     ["kong.plugins.proxy-cache.strategies"]           = "kong/plugins/proxy-cache/strategies/init.lua",
     ["kong.plugins.proxy-cache.strategies.memory"]    = "kong/plugins/proxy-cache/strategies/memory.lua",
+    ["kong.plugins.proxy-cache.clustering.compat.response_headers_translation"] = "kong/plugins/proxy-cache/clustering/compat/response_headers_translation.lua",
 
     ["kong.plugins.grpc-web.deco"] = "kong/plugins/grpc-web/deco.lua",
     ["kong.plugins.grpc-web.handler"] = "kong/plugins/grpc-web/handler.lua",

kong/clustering/compat/checkers.lua

@@ -23,6 +23,24 @@ end
 
 
 local compatible_checkers = {
+  { 3008000000, --[[ 3.8.0.0 ]]
+    function (config_table, dp_version, log_suffix)
+      local has_update
+      local adapter = require("kong.plugins.proxy-cache.clustering.compat.response_headers_translation").adapter
+      for _, plugin in ipairs(config_table.plugins or {}) do
+        if plugin.name == 'proxy-cache' then
+          has_update = adapter(plugin.config)
+          if has_update then
+            log_warn_message('adapts ' .. plugin.name .. ' plugin response_headers configuration to older version',
+                             'revert to older schema',
+                             dp_version, log_suffix)
+          end
+        end
+      end
+
+      return has_update
+    end
+  },
   { 3007000000, --[[ 3.7.0.0 ]]
     function(config_table, dp_version, log_suffix)
       local has_update

kong/plugins/proxy-cache/clustering/compat/response_headers_translation.lua

@@ -0,0 +1,13 @@
+local function adapter(config_to_update)
+    if config_to_update.response_headers["Age"] ~= nil then
+        config_to_update.response_headers.age = config_to_update.response_headers["Age"]
+        config_to_update.response_headers["Age"] = nil
+        return true
+    end
+
+    return false
+end
+
+return {
+    adapter = adapter
+}

kong/plugins/proxy-cache/schema.lua

@@ -78,7 +78,7 @@ return {
             description = "Caching related diagnostic headers that should be included in cached responses",
             type = "record",
             fields = {
-              { age  = {type = "boolean",  default = true} },
+              { ["Age"]  = {type = "boolean",  default = true} },
               { ["X-Cache-Status"]  = {type = "boolean",  default = true} },
               { ["X-Cache-Key"]  = {type = "boolean",  default = true} },
             },

spec/02-integration/09-hybrid_mode/09-config-compat_spec.lua

@@ -472,6 +472,46 @@ describe("CP/DP config compat transformations #" .. strategy, function()
           admin.plugins:remove({ id = response_rl.id })
         end)
       end)
+
+      describe("proxy-cache plugin", function()
+        it("rename age field in response_headers config from age to Age", function()
+          -- [[ 3.8.x ]] --
+          local response_rl = admin.plugins:insert {
+            name = "proxy-cache",
+            enabled = true,
+            config = {
+              response_code = { 200, 301, 404 },
+              request_method = { "GET", "HEAD" },
+              content_type = { "text/plain", "application/json" },
+              cache_ttl = 300,
+              strategy = "memory",
+              cache_control = false,
+              memory = {
+                dictionary_name = "kong_db_cache",
+              },
+              -- [[ age field renamed to Age
+              response_headers = {
+                ["Age"] = true,
+                ["X-Cache-Status"] = true,
+                ["X-Cache-Key"] = true
+              }
+              -- ]]
+            }
+          }
+
+          local expected_response_rl_prior_38 = cycle_aware_deep_copy(response_rl)
+          expected_response_rl_prior_38.config.response_headers = {
+            ["age"] = true,
+            ["X-Cache-Status"] = true,
+            ["X-Cache-Key"] = true
+          }
+
+          do_assert(uuid(), "3.7.0", expected_response_rl_prior_38)
+
+          -- cleanup
+          admin.plugins:remove({ id = response_rl.id })
+        end)
+      end)
     end)
 
     describe("ai plugins", function()

spec/03-plugins/31-proxy-cache/02-access_spec.lua

@@ -329,7 +329,7 @@ do
           content_type = { "text/plain", "application/json" },
           [policy] = policy_config,
           response_headers = {
-            age = false,
+            ["Age"] = false,
             ["X-Cache-Status"] = false,
             ["X-Cache-Key"]  = false
           },