From 225620da480f04041bcf1e1577dd63fcec01c68e Mon Sep 17 00:00:00 2001
From: Natalia Goc <goc_natalia@ma-al.com>
Date: Tue, 4 Jun 2024 13:02:29 +0200
Subject: [PATCH] feat: enable filtering console output by severity level

---
 example/main.go                                 |  8 +++++++-
 .../console_exporter/console_exporter.go        | 13 +++++++++++--
 pkg/level/level.go                              | 17 ++++++++++-------
 3 files changed, 28 insertions(+), 10 deletions(-)

diff --git a/example/main.go b/example/main.go
index 9efe544..586041e 100644
--- a/example/main.go
+++ b/example/main.go
@@ -23,7 +23,13 @@ func main() {
 	main := fiber.New()
 
 	exps := make([]exporters.TraceExporter, 0)
-	exps = append(exps, exporters.DevConsoleExporter(console_exporter.ProcessorOptions{}))
+
+	envFilter := "OBSERVER_CONSOLE"
+
+	exps = append(exps, exporters.DevConsoleExporter(console_exporter.ProcessorOptions{
+		FilterFromEnvVar: &envFilter,
+	}))
+
 	gelfExp, err := exporters.GelfExporter()
 	if err == nil {
 		exps = append(exps, gelfExp)
diff --git a/pkg/exporters/console_exporter/console_exporter.go b/pkg/exporters/console_exporter/console_exporter.go
index 284d45c..517ef54 100644
--- a/pkg/exporters/console_exporter/console_exporter.go
+++ b/pkg/exporters/console_exporter/console_exporter.go
@@ -3,6 +3,7 @@ package console_exporter
 import (
 	"context"
 	"fmt"
+	"os"
 	"slices"
 
 	"git.ma-al.com/maal-libraries/observer/pkg/attr"
@@ -22,7 +23,8 @@ type TraceFormatter interface {
 // Most of options are passed to the formatter.
 type ProcessorOptions struct {
 	// Try to parse filters from an environment variable with a name provided by this field.
-	// Result will only by applied to unset options. NOT IMPLEMENTED!
+	// Result will only by applied to unset options. Currently it will only attempt to parse
+	// severity level from the variable and use that as a filter.
 	FilterFromEnvVar *string
 	// Filter the output based on the [level.SeverityLevel].
 	FilterOnLevel level.SeverityLevel
@@ -79,9 +81,16 @@ func NewProcessor(opts ProcessorOptions) trace.SpanProcessor {
 		fmt := NewPrettyMultilineFormatter()
 		formatter = fmt
 	}
+	if opts.FilterFromEnvVar != nil {
+		envFilter := os.Getenv(*opts.FilterFromEnvVar)
+		parsedLvl := level.FromString(envFilter)
+		if parsedLvl != level.SeverityLevel(0) {
+			lvl = parsedLvl
+		}
+	}
 	if opts.FilterOnLevel != level.SeverityLevel(0) {
 		lvl = opts.FilterOnLevel
-	} else {
+	} else if lvl == level.SeverityLevel(0) {
 		lvl = level.TRACE + 1
 	}
 
diff --git a/pkg/level/level.go b/pkg/level/level.go
index bab75aa..f4c3c7b 100644
--- a/pkg/level/level.go
+++ b/pkg/level/level.go
@@ -1,6 +1,8 @@
 package level
 
 import (
+	"strings"
+
 	"git.ma-al.com/maal-libraries/observer/pkg/syslog"
 	"go.opentelemetry.io/otel/attribute"
 )
@@ -61,20 +63,21 @@ func (l SeverityLevel) String() string {
 }
 
 func FromString(level string) SeverityLevel {
+	level = strings.ToLower(level)
 	switch level {
-	case "ALERT":
+	case "alert":
 		return ALERT
-	case "CRIT":
+	case "crit", "critical":
 		return CRIT
-	case "ERR":
+	case "err", "error":
 		return ERR
-	case "WARN":
+	case "warn", "warning":
 		return WARN
-	case "INFO":
+	case "info":
 		return INFO
-	case "DEBUG":
+	case "debug":
 		return DEBUG
-	case "TRACE":
+	case "trace":
 		return TRACE
 	default:
 		return unset