terraform/helper/logging/logging.go

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package logging
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import (
"io"
"io/ioutil"
"log"
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"os"
"strings"
"syscall"
"github.com/hashicorp/logutils"
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)
// These are the environmental variables that determine if we log, and if
// we log whether or not the log should go to a file.
const (
EnvLog = "TF_LOG" // Set to True
EnvLogFile = "TF_LOG_PATH" // Set to a file
)
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var ValidLevels = []logutils.LogLevel{"TRACE", "DEBUG", "INFO", "WARN", "ERROR"}
// LogOutput determines where we should send logs (if anywhere) and the log level.
func LogOutput() (logOutput io.Writer, err error) {
logOutput = ioutil.Discard
logLevel := LogLevel()
if logLevel == "" {
return
}
logOutput = os.Stderr
if logPath := os.Getenv(EnvLogFile); logPath != "" {
var err error
logOutput, err = os.OpenFile(logPath, syscall.O_CREAT|syscall.O_RDWR|syscall.O_APPEND, 0666)
if err != nil {
return nil, err
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}
}
// This was the default since the beginning
logOutput = &logutils.LevelFilter{
Levels: ValidLevels,
MinLevel: logutils.LogLevel(logLevel),
Writer: logOutput,
}
return
}
// SetOutput checks for a log destination with LogOutput, and calls
// log.SetOutput with the result. If LogOutput returns nil, SetOutput uses
// ioutil.Discard. Any error from LogOutout is fatal.
func SetOutput() {
out, err := LogOutput()
if err != nil {
log.Fatal(err)
}
if out == nil {
out = ioutil.Discard
}
log.SetOutput(out)
}
// LogLevel returns the current log level string based the environment vars
func LogLevel() string {
envLevel := os.Getenv(EnvLog)
if envLevel == "" {
return ""
}
logLevel := "TRACE"
if isValidLogLevel(envLevel) {
// allow following for better ux: info, Info or INFO
logLevel = strings.ToUpper(envLevel)
} else {
log.Printf("[WARN] Invalid log level: %q. Defaulting to level: TRACE. Valid levels are: %+v",
envLevel, ValidLevels)
}
return logLevel
}
// IsDebugOrHigher returns whether or not the current log level is debug or trace
func IsDebugOrHigher() bool {
level := string(LogLevel())
return level == "DEBUG" || level == "TRACE"
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}
func isValidLogLevel(level string) bool {
for _, l := range ValidLevels {
if strings.ToUpper(level) == string(l) {
return true
}
}
return false
}