[go server] enable configurable writer (#775)

CHANGELOG.md

@@ -2,6 +2,8 @@
 
 ## Unreleased
 
+- Enable configurable Writer for log output (`go_server`) ([#775](https://github.com/mozilla/glean_parser/pull/775))
+
 ## 15.2.1
 
 - Allow earlier versions of platformdirs ([#769](https://github.com/mozilla/glean_parser/pull/769))

glean_parser/templates/go_server.jinja2

@@ -11,6 +11,7 @@ package glean
 import (
 	"encoding/json"
     "fmt"
+	"io"
 	"strconv"
 	"time"
 
@@ -20,10 +21,15 @@ import (
 // log type string used to identify logs to process in the Moz Data Pipeline
 var gleanEventMozlogType string = "glean-server-event"
 
+// A GleanEventsLogger produces output in the required format for Glean to ingest.
+// Glean ingestion requires the output to be written to os.Stdout. Writing to a different
+// output will require the consumer to handle any closing as appropriate for the Writer.
+// e.g. if writing to a file.
 type GleanEventsLogger struct {
 	AppID             string // Application Id to identify application per Glean standards
 	AppDisplayVersion string // Version of application emitting the event
 	AppChannel        string // Channel to differentiate logs from prod/beta/staging/devel
+	Writer            io.Writer // Writer to output to. Normal operation expects os.Stdout
 }
 
 // exported type for public method parameters
@@ -157,7 +163,9 @@ func (g GleanEventsLogger) record(
 	if envelopeErr != nil {
 		panic("Unable to marshal log envelope to json")
 	}
-	fmt.Println(string(envelopeJson))
+	if g.Writer != nil {
+		fmt.Fprintln(g.Writer, string(envelopeJson))
+	}
 }
 {# if any ping has an event metric, create methods and types for them #}
 {% if events %}

tests/data/server_custom_ping_only_compare.go

@@ -10,6 +10,7 @@ package glean
 import (
 	"encoding/json"
     "fmt"
+	"io"
 	"strconv"
 	"time"
 
@@ -19,10 +20,15 @@ import (
 // log type string used to identify logs to process in the Moz Data Pipeline
 var gleanEventMozlogType string = "glean-server-event"
 
+// A GleanEventsLogger produces output in the required format for Glean to ingest.
+// Glean ingestion requires the output to be written to os.Stdout. Writing to a different
+// output will require the consumer to handle any closing as appropriate for the Writer.
+// e.g. if writing to a file.
 type GleanEventsLogger struct {
 	AppID             string // Application Id to identify application per Glean standards
 	AppDisplayVersion string // Version of application emitting the event
 	AppChannel        string // Channel to differentiate logs from prod/beta/staging/devel
+	Writer            io.Writer // Writer to output to. Normal operation expects os.Stdout
 }
 
 // exported type for public method parameters
@@ -155,7 +161,9 @@ func (g GleanEventsLogger) record(
 	if envelopeErr != nil {
 		panic("Unable to marshal log envelope to json")
 	}
-	fmt.Println(string(envelopeJson))
+	if g.Writer != nil {
+		fmt.Fprintln(g.Writer, string(envelopeJson))
+	}
 }
 
 func newGleanEvent(category, name string, extra map[string]string) gleanEvent {

tests/data/server_events_and_custom_ping_compare.go

@@ -10,6 +10,7 @@ package glean
 import (
 	"encoding/json"
     "fmt"
+	"io"
 	"strconv"
 	"time"
 
@@ -19,10 +20,15 @@ import (
 // log type string used to identify logs to process in the Moz Data Pipeline
 var gleanEventMozlogType string = "glean-server-event"
 
+// A GleanEventsLogger produces output in the required format for Glean to ingest.
+// Glean ingestion requires the output to be written to os.Stdout. Writing to a different
+// output will require the consumer to handle any closing as appropriate for the Writer.
+// e.g. if writing to a file.
 type GleanEventsLogger struct {
 	AppID             string // Application Id to identify application per Glean standards
 	AppDisplayVersion string // Version of application emitting the event
 	AppChannel        string // Channel to differentiate logs from prod/beta/staging/devel
+	Writer            io.Writer // Writer to output to. Normal operation expects os.Stdout
 }
 
 // exported type for public method parameters
@@ -155,7 +161,9 @@ func (g GleanEventsLogger) record(
 	if envelopeErr != nil {
 		panic("Unable to marshal log envelope to json")
 	}
-	fmt.Println(string(envelopeJson))
+	if g.Writer != nil {
+		fmt.Fprintln(g.Writer, string(envelopeJson))
+	}
 }
 
 func newGleanEvent(category, name string, extra map[string]string) gleanEvent {

tests/data/server_events_only_compare.go

@@ -10,6 +10,7 @@ package glean
 import (
 	"encoding/json"
     "fmt"
+	"io"
 	"strconv"
 	"time"
 
@@ -19,10 +20,15 @@ import (
 // log type string used to identify logs to process in the Moz Data Pipeline
 var gleanEventMozlogType string = "glean-server-event"
 
+// A GleanEventsLogger produces output in the required format for Glean to ingest.
+// Glean ingestion requires the output to be written to os.Stdout. Writing to a different
+// output will require the consumer to handle any closing as appropriate for the Writer.
+// e.g. if writing to a file.
 type GleanEventsLogger struct {
 	AppID             string // Application Id to identify application per Glean standards
 	AppDisplayVersion string // Version of application emitting the event
 	AppChannel        string // Channel to differentiate logs from prod/beta/staging/devel
+	Writer            io.Writer // Writer to output to. Normal operation expects os.Stdout
 }
 
 // exported type for public method parameters
@@ -155,7 +161,9 @@ func (g GleanEventsLogger) record(
 	if envelopeErr != nil {
 		panic("Unable to marshal log envelope to json")
 	}
-	fmt.Println(string(envelopeJson))
+	if g.Writer != nil {
+		fmt.Fprintln(g.Writer, string(envelopeJson))
+	}
 }
 
 func newGleanEvent(category, name string, extra map[string]string) gleanEvent {

tests/test-go/test.go.tmpl

@@ -2,6 +2,7 @@ package main
 
 import (
   "glean/glean"
+  "os"
   "time"
 )
 
@@ -10,6 +11,7 @@ func main() {
     AppID:             "glean.test",
     AppDisplayVersion: "0.0.1",
     AppChannel:        "nightly",
+    Writer:            os.Stdout,
   }
 
   /* CODE */