feature: support to print log with specific prefix. (#1284)

lua/apisix/core/log.lua

@@ -14,12 +14,14 @@
 -- See the License for the specific language governing permissions and
 -- limitations under the License.
 --
+
 local ngx = ngx
 local ngx_log  = ngx.log
 local require  = require
+local setmetatable = setmetatable
 
 
-local _M = {version = 0.3}
+local _M = {version = 0.4}
 
 
 local log_levels = {
@@ -38,6 +40,33 @@ local log_levels = {
 local cur_level = ngx.config.subsystem == "http" and
                   require "ngx.errlog" .get_sys_filter_level()
 local do_nothing = function() end
+
+
+function _M.new(prefix)
+    local m = {version = _M.version}
+    setmetatable(m, {__index = function(self, cmd)
+        local log_level = log_levels[cmd]
+
+        local method
+        if cur_level and (log_level > cur_level)
+        then
+            method = do_nothing
+        else
+            method = function(...)
+                return ngx_log(log_level, prefix, ...)
+            end
+        end
+
+        -- cache the lazily generated method in our
+        -- module table
+        m[cmd] = method
+        return method
+    end})
+
+    return m
+end
+
+
 setmetatable(_M, {__index = function(self, cmd)
     local log_level = log_levels[cmd]
 

t/core/log.t

@@ -148,3 +148,27 @@ warn log
 notice log
 info log
 debug log
+
+
+
+=== TEST 6: print error log with prefix
+--- config
+    location /t {
+        content_by_lua_block {
+            local log = require("apisix.core").log.new("test: ")
+            log.error("error log")
+            log.warn("warn log")
+            log.notice("notice log")
+            log.info("info log")
+            ngx.say("done")
+        }
+    }
+--- log_level: error
+--- request
+GET /t
+--- error_log
+error log
+--- no_error_log
+test: warn log
+test: notice log
+test: info log