open-consul/logger/logger.go

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package logger
import (
"fmt"
"io"
"strings"
"time"
"github.com/hashicorp/go-syslog"
"github.com/hashicorp/logutils"
"github.com/mitchellh/cli"
)
// Config is used to set up logging.
type Config struct {
// LogLevel is the minimum level to be logged.
LogLevel string
// EnableSyslog controls forwarding to syslog.
EnableSyslog bool
// SyslogFacility is the destination for syslog forwarding.
SyslogFacility string
}
// Setup is used to perform setup of several logging objects:
//
// * A LevelFilter is used to perform filtering by log level.
// * A GatedWriter is used to buffer logs until startup UI operations are
// complete. After this is flushed then logs flow directly to output
// destinations.
// * A LogWriter provides a mean to temporarily hook logs, such as for running
// a command like "consul monitor".
// * An io.Writer is provided as the sink for all logs to flow to.
//
// The provided ui object will get any log messages related to setting up
// logging itself, and will also be hooked up to the gated logger. The final bool
// parameter indicates if logging was set up successfully.
func Setup(config *Config, ui cli.Ui) (*logutils.LevelFilter, *GatedWriter, *LogWriter, io.Writer, bool) {
// The gated writer buffers logs at startup and holds until it's flushed.
logGate := &GatedWriter{
Writer: &cli.UiWriter{ui},
}
// Set up the level filter.
logFilter := LevelFilter()
logFilter.MinLevel = logutils.LogLevel(strings.ToUpper(config.LogLevel))
logFilter.Writer = logGate
if !ValidateLevelFilter(logFilter.MinLevel, logFilter) {
ui.Error(fmt.Sprintf(
"Invalid log level: %s. Valid log levels are: %v",
logFilter.MinLevel, logFilter.Levels))
return nil, nil, nil, nil, false
}
// Set up syslog if it's enabled.
var syslog io.Writer
if config.EnableSyslog {
retries := 12
delay := 5 * time.Second
for i := 0; i <= retries; i++ {
l, err := gsyslog.NewLogger(gsyslog.LOG_NOTICE, config.SyslogFacility, "consul")
if err != nil {
ui.Error(fmt.Sprintf("Syslog setup error: %v", err))
if i == retries {
timeout := time.Duration(retries) * delay
ui.Error(fmt.Sprintf("Syslog setup did not succeed within timeout (%s).", timeout.String()))
return nil, nil, nil, nil, false
} else {
ui.Error(fmt.Sprintf("Retrying syslog setup in %s...", delay.String()))
time.Sleep(delay)
}
} else {
syslog = &SyslogWrapper{l, logFilter}
break
}
}
}
// Create a log writer, and wrap a logOutput around it
logWriter := NewLogWriter(512)
var logOutput io.Writer
if syslog != nil {
logOutput = io.MultiWriter(logFilter, logWriter, syslog)
} else {
logOutput = io.MultiWriter(logFilter, logWriter)
}
return logFilter, logGate, logWriter, logOutput, true
}