A SwiftLog LogHandler that logs GCP Stackdriver formatted JSON.
For more information on Stackdriver structured logging, see: https://cloud.google.com/logging/docs/structured-logging and LogEntry
This Stackdriver LogHandler depends on SwiftNIO which is used to create and save your new log entries in a non-blocking fashion.
.package(url: "https://github.com/Brainfinance/StackdriverLogging.git", from: "4.0.0"),In your target's dependencies add "StackdriverLogging" e.g. like this:
.target(name: "App", dependencies: ["StackdriverLogging"]),Here's a bootstrapping example for a standard Vapor 4 application.
import App
import Vapor
var env = try Environment.detect()
try LoggingSystem.bootstrap(from: &env) { (logLevel) -> (String) -> LogHandler in
return { label -> LogHandler in
var logger = StackdriverLogHandler(destination: .stdout)
logger.logLevel = logLevel
return logger
}
}
let app = Application(env)
defer { app.shutdown() }
try configure(app)
try app.run()To log metadata values as JSON, simply log all JSON values other than String as a Logger.MetadataValue.stringConvertible and, instead of the usual conversion of your value to a String in the log entry, it will keep the original JSON type of your values whenever possible.
For example:
var logger = Logger(label: "Stackdriver")
logger[metadataKey: "jsonpayload-example-object"] = [
"json-null": .stringConvertible(NSNull()),
"json-bool": .stringConvertible(true),
"json-integer": .stringConvertible(1),
"json-float": .stringConvertible(1.5),
"json-string": .string("Example"),
"stackdriver-timestamp": .stringConvertible(Date()),
"json-array-of-numbers": [.stringConvertible(1), .stringConvertible(5.8)],
"json-object": [
"key": "value"
]
]
logger.info("test")Will log the non pretty-printed representation of:
{
"sourceLocation":{
"function":"boot(_:)",
"file":"\/Sources\/App\/boot.swift",
"line":25
},
"jsonpayload-example-object":{
"json-bool":true,
"json-float":1.5,
"json-string":"Example",
"json-object":{
"key":"value"
},
"json-null":null,
"json-integer":1,
"json-array-of-numbers":[
1,
5.8
],
"stackdriver-timestamp":"2019-07-15T21:21:02.451Z"
},
"message":"test",
"severity":"INFO"
}If your app is running inside a managed environment such as Google Cloud Run or a container based Compute Engine, logging to stdout should get you up and running automatically.
If you prefer logging to a file, you can use a file destination StackdriverLogHandler.Destination.file in combination with the Stackdriver logging agent https://cloud.google.com/logging/docs/agent/installation and a matching json format
google-fluentd config (/etc/google-fluentd/config.d/example.conf) to automatically send your JSON logs to Stackdriver for you.
Here's an example google-fluentd conf file that monitors a json based logfile and send new log entries to Stackdriver:
<source>
@type tail
# Format 'JSON' indicates the log is structured (JSON).
format json
# The path of the log file.
path /var/log/example.log
# The path of the position file that records where in the log file
# we have processed already. This is useful when the agent
# restarts.
pos_file /var/lib/google-fluentd/pos/example-log.pos
read_from_head true
# The log tag for this log input.
tag exampletag
</source>