feat: enable filtering console output by severity level

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
 	}