Product
Introducing License Enforcement in Socket
Ensure open-source compliance with Socket’s License Enforcement Beta. Set up your License Policy and secure your software!
github.com/ssgreg/journald
Package journald
offers Go implementation of systemd Journal's native API for logging. Key features are:
Install the package with:
go get github.com/ssgreg/journald
The Best Way to use structured logs (systemd Journal, etc.) is logf - the fast, asynchronous, structured logger in Go with zero allocation count and it's journald driver logfjournald. This driver uses journald
package.
The following example creates the new logf
logger with logfjournald
appender.
package main
import (
"runtime"
"github.com/ssgreg/logf"
"github.com/ssgreg/logfjournald"
)
func main() {
// Create journald Appender with default journald Encoder.
appender, appenderClose := logfjournald.NewAppender(logfjournald.NewEncoder.Default())
defer appenderClose()
// Create ChannelWriter with journald Encoder.
writer, writerClose := logf.NewChannelWriter(logf.ChannelWriterConfig{
Appender: appender,
})
defer writerClose()
// Create Logger with ChannelWriter.
logger := logf.NewLogger(logf.LevelInfo, writer)
logger.Info("got cpu info", logf.Int("count", runtime.NumCPU()))
}
The JSON representation of the journal entry this generates:
{
"TS": "2018-11-01T07:25:18Z",
"PRIORITY": "6",
"LEVEL": "info",
"MESSAGE": "got cpu info",
"COUNT": "4",
}
Let's look at what the journald
provides as Go APIs for logging:
package main
import (
"github.com/ssgreg/journald"
)
func main() {
journald.Print(journald.PriorityInfo, "Hello World!")
}
The JSON representation of the journal entry this generates:
{
"PRIORITY": "6",
"MESSAGE": "Hello World!",
"_PID": "3965",
"_COMM": "simple",
"...": "..."
}
The primary reason for using the Journal's native logging APIs is not just plain logs: it is to allow passing additional structured log messages from the program into the journal. This additional log data may the be used to search the journal for, is available for consumption for other programs, and might help the administrator to track down issues beyond what is expressed in the human readable message text. Here's an example how to do that with journals.Send
:
package main
import (
"os"
"runtime"
"github.com/ssgreg/journald"
)
func main() {
journald.Send("Hello World!", journald.PriorityInfo, map[string]interface{}{
"HOME": os.Getenv("HOME"),
"TERM": os.Getenv("TERM"),
"N_GOROUTINE": runtime.NumGoroutine(),
"N_CPUS": runtime.NumCPU(),
"TRACE": runtime.ReadTrace(),
})
}
This will write a log message to the journal much like the earlier examples. However, this times a few additional, structured fields are attached:
{
"PRIORITY": "6",
"MESSAGE": "Hello World!",
"HOME": "/root",
"TERM": "xterm",
"N_GOROUTINE": "2",
"N_CPUS": "4",
"TRACE": [103,111,32,49,46,56,32,116,114,97,99,101,0,0,0,0],
"_PID": "4037",
"_COMM": "send",
"...": "..."
}
Our structured message includes seven fields. The first two we passed are well-known fields:
MESSAGE=
is the actual human readable message part of the structured message.PRIORITY=
is the numeric message priority value as known from BSD syslog formatted as an integer string.Applications may relatively freely define additional fields as they see fit (we defined four pretty arbitrary ones in our example). A complete list of the currently well-known fields is available here.
Thanks to http://0pointer.de/blog/ for the inspiration.
FAQs
Unknown package
Did you know?
Socket for GitHub automatically highlights issues in each pull request and monitors the health of all your open source dependencies. Discover the contents of your packages and block harmful activity before you install or update your dependencies.
Product
Ensure open-source compliance with Socket’s License Enforcement Beta. Set up your License Policy and secure your software!
Product
We're launching a new set of license analysis and compliance features for analyzing, managing, and complying with licenses across a range of supported languages and ecosystems.
Product
We're excited to introduce Socket Optimize, a powerful CLI command to secure open source dependencies with tested, optimized package overrides.