example for changing logging level by public function, called with HT…

examples/setLogLevels.go

@@ -0,0 +1,140 @@
+package main
+
+import (
+	"errors"
+	"io/ioutil"
+	"net/http"
+	"strconv"
+	"strings"
+
+	"github.com/romana/rlog"
+	"gopkg.in/gin-gonic/gin.v1"
+)
+
+// It is necessary to have a rlog configuration file with entries for both: RLOG_LOG_LEVEL and RLOG_TRACE_LEVEL
+// the const variables were copied from rlog
+//
+// The known log levels
+const (
+	levelNone = iota
+	levelCrit
+	levelErr
+	levelWarn
+	levelInfo
+	levelDebug
+	levelTrace
+)
+
+// Translation map from level to string representation
+var levelStrings = map[int]string{
+	levelTrace: "TRACE",
+	levelDebug: "DEBUG",
+	levelInfo:  "INFO",
+	levelWarn:  "WARN",
+	levelErr:   "ERROR",
+	levelCrit:  "CRITICAL",
+	levelNone:  "NONE",
+}
+
+// Translation from level string to number.
+var levelNumbers = map[string]int{
+	"TRACE":    levelTrace,
+	"DEBUG":    levelDebug,
+	"INFO":     levelInfo,
+	"WARN":     levelWarn,
+	"ERROR":    levelErr,
+	"CRITICAL": levelCrit,
+	"NONE":     levelNone,
+}
+
+// Path to the config file. Defined here for standalone example purpose
+const (
+	rlogConfigFile      = "/tmp/rlog.conf"
+	rlogConfigFileUmask = 0644
+)
+
+// LogConfHandler is a handler function for the gin-gonic framework to change trace and log level
+func LogConfHandler(c *gin.Context) {
+
+	// get HTTP GET params
+	level := c.Query("level")
+	trace := c.Query("trace")
+
+	traceInt, err := strconv.Atoi(trace)
+
+	// continue if trace is an integer
+	if err == nil {
+		err := setGlobalLogConf(level, traceInt)
+
+		if err != nil {
+			c.String(http.StatusInternalServerError, err.Error())
+			return
+		}
+	}
+
+	c.String(http.StatusOK, "setting log level to "+level+" trace "+trace)
+}
+
+// setGlobalLogConf to change logging settings while running
+func setGlobalLogConf(level string, trace int) error {
+
+	// check if specified log level is within allowed values
+	if _, ok := levelNumbers[level]; ok {
+		// check for config file
+		configFile, err := ioutil.ReadFile(rlogConfigFile)
+		if err != nil {
+			return errors.New("could not read config file: " + err.Error())
+		}
+
+		// replace config lines
+		lines := strings.Split(string(configFile), "\n")
+
+		// check for pre-existing values in config, override or append
+		hasLogLevelEntry := false
+		hasTraceLevelEntry := false
+
+		for i, line := range lines {
+			if strings.Contains(line, "RLOG_LOG_LEVEL") {
+				lines[i] = "RLOG_LOG_LEVEL = " + level
+				hasLogLevelEntry = true
+				continue
+			}
+
+			if strings.Contains(line, "RLOG_TRACE_LEVEL") {
+				lines[i] = "RLOG_TRACE_LEVEL = " + strconv.Itoa(trace)
+				hasTraceLevelEntry = true
+			}
+		}
+
+		// append new options if neccessary
+		if !hasLogLevelEntry {
+			lines = append(lines, "RLOG_LOG_LEVEL = "+level)
+		}
+		if !hasTraceLevelEntry {
+			lines = append(lines, "RLOG_TRACE_LEVEL = "+strconv.Itoa(trace))
+		}
+
+		output := strings.Join(lines, "\n")
+		err = ioutil.WriteFile(rlogConfigFile, []byte(output), rlogConfigFileUmask)
+
+		if err != nil {
+			return errors.New("could not replace config file: " + err.Error())
+
+		}
+
+		// set new config
+		rlog.SetConfFile(rlogConfigFile)
+
+		return nil
+	}
+
+	return errors.New("invalid value for level, must be valid rlog log level")
+}
+
+func main() {
+	// check file contents of rlogConfFile to see results e.g. with: "cat /tmp/rlog.conf" before and after
+	setGlobalLogConf("DEBUG", 1)
+	rlog.Trace(3, "this will not appear in the log")
+	setGlobalLogConf("DEBUG", 3)
+	rlog.Trace(3, "this will appear in the log")
+}