fix: closing brace should not be a part of variable (#10485)

apisix/core/utils.lua

@@ -292,11 +292,13 @@ local resolve_var
 do
     local _ctx
     local n_resolved
-    local pat = [[(?<!\\)\$\{?(\w+)\}?]]
+    local pat = [[(?<!\\)\$(\{(\w+)\}|(\w+))]]
     local _escaper
 
     local function resolve(m)
-        local v = _ctx[m[1]]
+        local variable = m[2] or m[3]
+        local v = _ctx[variable]
+
         if v == nil then
             return ""
         end

t/plugin/fault-injection2.t

@@ -140,3 +140,47 @@ GET /hello
 h1: v1
 h2: 2
 h3: /hello
+
+
+
+=== TEST 6: closing curly brace not should not be a part of variable
+--- config
+ location /t {
+           content_by_lua_block {
+               local t = require("lib.test_admin").test
+               local code, body = t('/apisix/admin/routes/1',
+                    ngx.HTTP_PUT,
+                    [=[{
+                            "plugins": {
+                               "fault-injection": {
+                                   "abort": {
+                                      "http_status": 200,
+                                      "body": "{\"count\": $arg_count}"
+                                   }
+                               }
+                            },
+                            "upstream": {
+                               "nodes": {
+                                   "127.0.0.1:1980": 1
+                               },
+                               "type": "roundrobin"
+                            },
+                            "uri": "/hello"
+                        }]=]
+                   )
+               if code >= 300 then
+                   ngx.status = code
+               end
+               ngx.say(body)
+           }
+       }
+--- response_body
+passed
+
+
+
+=== TEST 7: test route
+--- request
+GET /hello?count=2
+--- response_body chomp
+{"count": 2}