Just another logging module that supports logging of structured Json protocol messages. The main feature is the ability to send log messages and metrics to cloud services such as Azure Monitor (Azure Log Analytics Workspaces) and Elasticsearch. By implementing the LogWriters interface it can be extended to log to additional log stores.
The following log writers are part of the logwriter package:
- Azure Monitor - to log into Azure Log Analytics Workspaces
- ElasticSearch - to log into an ElasticSearch database (In Progress)
Before trying the code, ensure that relevant environment variables are set (see Configuraiton).
package main
import (
"github.com/mfmayer/logthing"
"github.com/mfmayer/logthing/logwriter"
)
func main() {
// Init the dispatcher with an Azure Monitoro writer
if err := logthing.InitDispatcher([]logwriter.LogWriter{
logwriter.NewAzureMonitorWriter(),
}); err != nil {
logthing.Error.Printf("Error init dispatcher: %v", err)
}
logMsg := logthing.NewLogMsg("<some_type>")
logMsg.SetTrackingID("<some_tracking_id>") // Add a tracking id
logMsg.SetProperty("foo_bar", 12345) // set a property
logMsg.SetProperty("foo", 12345) // set a property
logMsg.SetProperty("bar", []int{5, 6, 7, 8}) // set another property
logMsg.Infof("Hello %v", []string{"World", "Moon"}) // set an info message
logthing.Log(logMsg) // log the message
// The calls can be also lined up as in this additional example:
logthing.NewLogMsg("<another_type>").
Infof("Hello %v", []string{"Mom", "Dad"}). // add an info message
SetSProperty("windS", map[string]interface{}{"speed": 10, "directions": 25.5}). // add stringified wind property
SetProperty("wind", map[string]interface{}{"speed": 10, "directions": 25.5}). // add non-stringified wind property
SetProperty("rain", 10). // add rain property
Warningf("The weather is %v", []string{"rainy", "stormy"}). // add a warning message
Log() // log the message
logthing.Close()
}
/* Outputs:
INFO: 2020/09/02 20:47:14 logthing_test.go:23: logthing_test.go:22: Hello [World Moon] ([foo:12345 trackingID:<some_tracking_id>])
WARN: 2020/09/02 20:47:14 logthing_test.go:32: logthing_test.go:27: Hello [Mom Dad]
logthing_test.go:31: The weather is [rainy stormy]
*/Since logthing is meant for service logging and also credentials must be somehow given to logthing, most of the configuration happens via environment variables:
| Environment Variable | Description |
|---|---|
| LOGTHING_LOG_NAME | Log name under which log messages are stored (will be used as elasticsearch index or azure custom log type) |
| LOGTHING_LOG_MAX_SEVERITY | Messages with severity > LOGTHING_LOG_MAX_SEVERITY won't be logged and are immediately dropped |
| LOGTHING_WHITELIST_LOG_TYPES | Messages that match any whitelisted log type (comma separated) are logged independent of their severity |
| LOGTHING_PRINT_MAX_SEVERITY | Messages with severity <= LOG_OUTPUT_SEVERITY_MAX are directly printed to stdout / stderr |
| LOGTHING_PRINT_PROPERTIES | Message properties that match any give print property (comma separated) are printed with the message output |
| LOGTHING_WHITELIST_PROPERTIES | If stated (not empty), only whitelisted properties will be logged |
For the Azure Monitor writer additional environment variables must be set (for details how the used API is working see: https://docs.microsoft.com/de-de/azure/azure-monitor/platform/data-collector-api):
| Environment Variable | Description |
|---|---|
| LOGTHING_AZURE_WORKSPACE_ID | Azure log analytics workspace id |
| LOGTHING_AZURE_WORKSPACE_KEY | Azure log analytics worksoace key |
| LOGTHING_AZURE_MONITOR_DOMAIN | To overwrite the default azure monitor domain |
For ElasticSearch the following environment variables are needed:
| Environment Variable | Description |
|---|---|
| ELASTICSEARCH_URL | The URL under which the database can be accessed |
| ELASTICSEARCH_USER | ElasticSearch Username |
| ELASTICSEARCH_PWD | ElasticSearch Password |