go-log

The logging library used by go-ipfs

go-log wraps zap to provide a logging facade. go-log manages logging instances and allows for their levels to be controlled individually.

Install

go get github.com/ipfs/go-log

Usage

Once the package is imported under the name logging, an instance of EventLogger can be created like so:

var log = logging.Logger("subsystem name")

It can then be used to emit log messages in plain printf-style messages at seven standard levels:

Levels may be set for all loggers:

lvl, err := logging.LevelFromString("error")
if err != nil {
	panic(err)
}
logging.SetAllLoggers(lvl)

or individually:

err := logging.SetLogLevel("net:pubsub", "info")
if err != nil {
	panic(err)
}

or by regular expression:

err := logging.SetLogLevelRegex("net:.*", "info")
if err != nil {
	panic(err)
}

Environment Variables

This package can be configured through various environment variables.

GOLOG_LOG_LEVEL

Specifies the log-level, both globally and on a per-subsystem basis.

For example, the following will set the global minimum log level to error, but reduce the minimum log level for subsystem1 to info and reduce the minimum log level for subsystem2 to debug.

export GOLOG_LOG_LEVEL="error,subsystem1=info,subsystem2=debug"

IPFS_LOGGING is a deprecated alias for this environment variable.

GOLOG_FILE

Specifies that logs should be written to the specified file. If this option is not specified, logs are written to standard error.

export GOLOG_FILE="/path/to/my/file.log"

GOLOG_OUTPUT

Specifies where logging output should be written. Can take one or more of the following values, combined with +:

• stdout -- write logs to standard out.
• stderr -- write logs to standard error.
• file -- write logs to the file specified by GOLOG_FILE

For example, if you want to log to both a file and standard error:

export GOLOG_FILE="/path/to/my/file.log"
export GOLOG_OUTPUT="stderr+file"

Setting only GOLOG_FILE will prevent logs from being written to standard error.

GOLOG_LOG_FMT

Specifies the log message format. It supports the following values:

• color -- human readable, colorized (ANSI) output
• nocolor -- human readable, plain-text output.
• json -- structured JSON.

For example, to log structured JSON (for easier parsing):

export GOLOG_LOG_FMT="json"

The logging format defaults to color when the output is a terminal, and nocolor otherwise.

IPFS_LOGGING_FMT is a deprecated alias for this environment variable.

GOLOG_LOG_LABELS

Specifies a set of labels that should be added to all log messages as comma-separated key-value pairs. For example, the following add {"app": "example_app", "dc": "sjc-1"} to every log entry.

export GOLOG_LOG_LABELS="app=example_app,dc=sjc-1"

Contribute

Feel free to join in. All welcome. Open an issue!

This repository falls under the IPFS Code of Conduct.

Want to hack on IPFS?

License

MIT