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Perfect Logging (File & Remote)

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Swift 3.0 Platforms OS X | Linux License Apache PerfectlySoft Twitter Slack Status

Using the PerfectLogger module, events can be logged to a specfied file, in addition to the console.

Support is also included in this module for remote logging events to the Perfect Log Server.

Using in your project

Add the dependancy to your project's Package.swift file:

.Package(url: "https://github.com/PerfectlySoft/Perfect-Logger.git", majorVersion: 3),

Now add the import directive to the file you wish to use the logging in:

import PerfectLogger

To log events to the local console as well as a file:

LogFile.debug("debug message", logFile: "test.txt")
LogFile.info("info message", logFile: "test.txt")
LogFile.warning("warning message", logFile: "test.txt")
LogFile.error("error message", logFile: "test.txt")
LogFile.critical("critical message", logFile: "test.txt")
LogFile.terminal("terminal message", logFile: "test.txt")

To log to the default file, omit the file name parameter.

Linking events with "eventid"

Each log event returns an event id string. If an eventid string is supplied to the directive then it will use the supplied eventid in the log file instead - this makes it easy to link together related events.

let eid = LogFile.warning("test 1")
LogFile.critical("test 2", eventid: eid)

returns:

[WARNING] [62f940aa-f204-43ed-9934-166896eda21c] [2016-11-16 15:18:02 GMT-05:00] test 1
[CRITICAL] [62f940aa-f204-43ed-9934-166896eda21c] [2016-11-16 15:18:02 GMT-05:00] test 2

The returned eventid is marked @discardableResult therefore can be safely ignored if not required for re-use.

Customization

Setting a custom Logfile location

The default logfile location is ./log.log. To set a custom logfile location, set the LogFile.location variable:

LogFile.location = "/var/log/myLog.log"

Messages can now be logged directly to the file as set by using:

LogFile.debug("debug message")
LogFile.info("info message")
LogFile.warning("warning message")
LogFile.error("error message")
LogFile.critical("critical message")
LogFile.terminal("terminal message")

LogFile threshold

For debug purposes, you want to see as much info as available. However, on production servers you probably desire a smaller logfile and filter out all redundant info.

To do so, you may set the LogFile's threshold property to the minumum priority you want to actually being logged into the file.

e.g.:

LogFile.threshold = .warning
LogFile.debug("This won't be logged into the file")
LogFile.info("This won't be logged into the file")
LogFile.warning("This will be logged into the file")
LogFile.error("This will be logged into the file")
LogFile.critical("This will be logged into the file")

The default value of this property is .debug to preserve backward compatibility and this property will not affect the Console/Remote logger.

LogFile options

Depending on your needs, you may not be interested in an event id, timestamp or priority.

Using the LogFile's options property you can customize which of those fields will actually be added as a prefix to the log message.

e.g.:

// Default behaviour (equal to `[.priority, .eventId, .timestamp]`)
LogFile.options = .default
LogFile.debug("This is my log message")
// Will log: "[DEBUG] [CEC5B5DB-931F-4C5A-A794-17D060BABC80] [2019-05-04 15:16:11 GMT+02:00] This is my log message"

LogFile.options = .none
LogFile.debug("This is my log message")
// Will log: "This is my log message"

LogFile.options = [.priority, .timestamp]
LogFile.debug("This is my log message")
// Will log: "[DEBUG] [2019-05-04 15:16:11 GMT+02:00] This is my log message"

LogFile.options = [.priority]
LogFile.debug("This is my log message")
// Will log: "[DEBUG] This is my log message"

Sample output

[DEBUG] [ec6a9ca5-00b1-4656-9e4c-ddecae8dde02] [2016-11-16 15:18:02 GMT-05:00] a debug message
[INFO] [ec6a9ca5-00b1-4656-9e4c-ddecae8dde02] [2016-11-16 15:18:02 GMT-05:00] an informational message
[WARNING] [ec6a9ca5-00b1-4656-9e4c-ddecae8dde02] [2016-11-16 15:18:02 GMT-05:00] a warning message
[ERROR] [62f940aa-f204-43ed-9934-166896eda21c] [2016-11-16 15:18:02 GMT-05:00] an error message
[CRITICAL] [62f940aa-f204-43ed-9934-166896eda21c] [2016-11-16 15:18:02 GMT-05:00] a critical message
[EMERG] [ec6a9ca5-00b1-4656-9e4c-ddecae8dde02] [2016-11-16 15:18:02 GMT-05:00] an emergency message

Remote Logging

The "Perfect-Logging" dependency includes support for remote logging to this log server.

To include the dependency in your project, add the following to your project's Package.swift file:

.Package(url: "https://github.com/PerfectlySoft/Perfect-Logger.git", majorVersion: 3),

Now add the import directive to the file you wish to use the logging in:

import PerfectLogger

Configuration

Three configuration parameters are required:

// Your token
RemoteLogger.token = "<your token>"

// App ID (Optional)
RemoteLogger.appid = "<your appid>"

// URL to access the log server. 
// Note, this is not the full API path, just the host and port.
RemoteLogger.logServer = "http://localhost:8181"

To log events to the log server:

var obj = [String: Any]()
obj["one"] = "donkey"
RemoteLogger.critical(obj)

Linking events with "eventid"

Each log event returns an event id string. If an eventid string is supplied to the directive then it will use the supplied eventid in the log directive instead - this makes it easy to link together related events.

let eid = RemoteLogger.critical(obj)
RemoteLogger.info(obj, eventid: eid)

The returned eventid is marked @discardableResult therefore can be safely ignored if not required for re-use.

Further Information

For more information on the Perfect project, please visit perfect.org.