From 1bd627c2b176f0691f72dfd06f267cedc7414cc5 Mon Sep 17 00:00:00 2001
From: Arthur Chaloin <arthur@achaloin.com>
Date: Wed, 14 Oct 2020 14:50:25 +0200
Subject: [PATCH] feat(exporter): --trim-path-components option

---
 cmd/x509-exporter/main.go      | 14 +++++++-------
 cmd/x509-exporter/main_test.go | 12 ++++++------
 internal/collector.go          | 11 ++++++++---
 internal/exporter.go           | 12 ++++++------
 4 files changed, 27 insertions(+), 22 deletions(-)

diff --git a/cmd/x509-exporter/main.go b/cmd/x509-exporter/main.go
index 9cb1302..d07e735 100644
--- a/cmd/x509-exporter/main.go
+++ b/cmd/x509-exporter/main.go
@@ -21,7 +21,7 @@ func main() {
 	help := getopt.BoolLong("help", 'h', "show this help message and exit")
 	port := getopt.IntLong("port", 'p', 9090, "prometheus exporter listening port")
 	debug := getopt.BoolLong("debug", 0, "enable debug mode")
-	trimPath := getopt.StringLong("trim-path", 0, "", "remove leading elements from path(s) in label(s)")
+	trimPathComponents := getopt.IntLong("trim-path-components", 0, 0, "remove <n> leading component(s) from path(s) in label(s)")
 
 	files := stringArrayFlag{}
 	getopt.FlagLong(&files, "watch-file", 'f', "watch one or more x509 certificate file")
@@ -55,12 +55,12 @@ func main() {
 	}
 
 	exporter := exporter.Exporter{
-		Port:        *port,
-		Files:       files,
-		Directories: directories,
-		YAMLs:       kubeconfigs,
-		YAMLPaths:   exporter.DefaultYamlPaths,
-		TrimPath:    *trimPath,
+		Port:               *port,
+		Files:              files,
+		Directories:        directories,
+		YAMLs:              kubeconfigs,
+		YAMLPaths:          exporter.DefaultYamlPaths,
+		TrimPathComponents: *trimPathComponents,
 	}
 
 	exporter.ListenAndServe()
diff --git a/cmd/x509-exporter/main_test.go b/cmd/x509-exporter/main_test.go
index 7c141a9..8c0e6f3 100644
--- a/cmd/x509-exporter/main_test.go
+++ b/cmd/x509-exporter/main_test.go
@@ -389,21 +389,21 @@ func TestTrimPath(t *testing.T) {
 	generateCertificate(certPath, time.Now())
 
 	testRequest(t, &exporter.Exporter{
-		Port:     port,
-		Files:    []string{certPath},
-		TrimPath: "/tmp/",
+		Port:               port,
+		Files:              []string{certPath},
+		TrimPathComponents: 1,
 	}, func(metrics []model.MetricFamily) {
 		foundMetrics := getMetricsForName(metrics, "x509_cert_expired")
 		assert.Len(t, foundMetrics, 1, "missing x509_cert_expired metric(s)")
-		checkLabels(t, foundMetrics[0].GetLabel(), "test.pem")
+		checkLabels(t, foundMetrics[0].GetLabel(), "/test.pem")
 
 		foundNbMetrics := getMetricsForName(metrics, "x509_cert_not_before")
 		assert.Len(t, foundNbMetrics, 1, "missing x509_cert_not_before metric(s)")
-		checkLabels(t, foundNbMetrics[0].GetLabel(), "test.pem")
+		checkLabels(t, foundNbMetrics[0].GetLabel(), "/test.pem")
 
 		foundNaMetrics := getMetricsForName(metrics, "x509_cert_not_after")
 		assert.Len(t, foundNaMetrics, 1, "missing x509_cert_not_after metric(s)")
-		checkLabels(t, foundNaMetrics[0].GetLabel(), "test.pem")
+		checkLabels(t, foundNaMetrics[0].GetLabel(), "/test.pem")
 
 		os.Remove(certPath)
 	})
diff --git a/internal/collector.go b/internal/collector.go
index ca84e0e..a7e69ee 100644
--- a/internal/collector.go
+++ b/internal/collector.go
@@ -3,6 +3,7 @@ package internal
 import (
 	"crypto/x509/pkix"
 	"fmt"
+	"path"
 	"path/filepath"
 	"strings"
 	"time"
@@ -66,10 +67,14 @@ func (collector *collector) Collect(ch chan<- prometheus.Metric) {
 }
 
 func (collector *collector) getMetricsForCertificate(certData *parsedCertificate, ref *certificateRef) []prometheus.Metric {
-	trimmedFilePath := ref.path
-	if ref.path[:len(collector.exporter.TrimPath)] == collector.exporter.TrimPath {
-		trimmedFilePath = trimmedFilePath[len(collector.exporter.TrimPath):]
+	trimComponentsCount := collector.exporter.TrimPathComponents
+	pathComponents := strings.Split(ref.path, "/")
+	prefix := ""
+	if pathComponents[0] == "" {
+		trimComponentsCount++
+		prefix = "/"
 	}
+	trimmedFilePath := path.Join(prefix, path.Join(pathComponents[trimComponentsCount:]...))
 
 	baseLabels := []string{
 		"filename",
diff --git a/internal/exporter.go b/internal/exporter.go
index a1737b2..26d5f24 100644
--- a/internal/exporter.go
+++ b/internal/exporter.go
@@ -15,12 +15,12 @@ import (
 
 // Exporter : Configuration (from command-line)
 type Exporter struct {
-	Port        int
-	Files       []string
-	Directories []string
-	YAMLs       []string
-	YAMLPaths   []YAMLCertRef
-	TrimPath    string
+	Port               int
+	Files              []string
+	Directories        []string
+	YAMLs              []string
+	YAMLPaths          []YAMLCertRef
+	TrimPathComponents int
 
 	listener    net.Listener
 	handler     *http.Handler