First implementation

This parses the transaction files and generates two metrics.

.github/workflows/build.yml

@@ -0,0 +1,30 @@
+name: Build and Test
+
+on:
+  push:
+    branches:
+      - main
+  pull_request:
+    branches:
+      - main
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+
+    steps:
+    - uses: actions/checkout@v3
+
+    - name: Set up Go
+      uses: actions/setup-go@v4
+      with:
+        go-version: 1.23
+
+    - name: Install dependencies
+      run: go mod tidy
+
+    - name: Build
+      run: make build
+
+    - name: Test
+      run: make test

.gitignore

@@ -1,21 +1 @@
-# Generated by Cargo
-# will have compiled files and executables
-debug/
-target/
-
-# Remove Cargo.lock from gitignore if creating an executable, leave it for libraries
-# More information here https://doc.rust-lang.org/cargo/guide/cargo-toml-vs-cargo-lock.html
-Cargo.lock
-
-# These are backup files generated by rustfmt
-**/*.rs.bk
-
-# MSVC Windows builds of rustc generate these, which store debugging information
-*.pdb
-
-# RustRover
-#  JetBrains specific template is maintained in a separate JetBrains.gitignore that can
-#  be found at https://github.com/github/gitignore/blob/main/Global/JetBrains.gitignore
-#  and can be added to the global gitignore or merged into this file.  For a more nuclear
-#  option (not recommended) you can uncomment the following to ignore the entire idea folder.
-#.idea/
+borgbackuptransactions_exporter

CONTRIBUTING.md

@@ -0,0 +1,8 @@
+# Contributing
+
+We welcome contributions! Please follow these guidelines:
+1. Fork the repository and create a feature branch.
+2. Submit a pull request with a clear description of your changes.
+3. Ensure all tests pass before submitting.
+
+**Do not add features which require extra credentials on borg, they will be rejected.**

Makefile

@@ -0,0 +1,8 @@
+build:
+	go build -o borgbackuptransactions_exporter .
+
+test:
+	go test ./...
+
+clean:
+	rm -f borgbackuptransactions_exporter

README

@@ -0,0 +1,40 @@
+# Borg transactions prometheus exporter
+
+A Prometheus exporter for monitoring BorgBackup repositories without their passphrases.
+This reports the transaction happening on monitored repos, as this can be parsed without the passphrase.
+
+This is appropriate for monitoring on a server in which you do not want to store credentials.
+You should add other monitoring tools to check consistency with other exporters.
+
+## Features
+- Metrics for the last transaction timestamp and number for each repository.
+- Configurable via a JSON file.
+
+## Usage
+
+1. Create a `config.json` file:
+    ```json
+    {
+      "repos": ["/path/to/repo1", "/path/to/repo2"],
+      "ip": "0.0.0.0",
+      "port": 8080,
+      "endpoint": "/metrics"
+    }
+    ```
+2. Run the exporter:
+    ```bash
+    ./borgbackuptransactions_exporter --config=config.json
+    ```
+
+### Metrics exposed
+- `borgbackup_last_transaction_timestamp`
+- `borgbackup_last_transaction_number`
+
+### How to scrape
+
+```
+scrape_configs:
+  - job_name: "borgbackuptransactions_exporter"
+    static_configs:
+      - targets: ["localhost:8080"]
+```

example_config.json

@@ -0,0 +1,7 @@
+{
+  "repos": [
+    "testdata"
+  ],
+  "ip": "127.0.0.1",
+  "port": 9999
+}

go.mod

@@ -0,0 +1,17 @@
+module tlaas.be/borg-backup-transactions-exporter
+
+go 1.23.3
+
+require github.com/prometheus/client_golang v1.20.5
+
+require (
+	github.com/beorn7/perks v1.0.1 // indirect
+	github.com/cespare/xxhash/v2 v2.3.0 // indirect
+	github.com/klauspost/compress v1.17.9 // indirect
+	github.com/munnerz/goautoneg v0.0.0-20191010083416-a7dc8b61c822 // indirect
+	github.com/prometheus/client_model v0.6.1 // indirect
+	github.com/prometheus/common v0.55.0 // indirect
+	github.com/prometheus/procfs v0.15.1 // indirect
+	golang.org/x/sys v0.22.0 // indirect
+	google.golang.org/protobuf v1.34.2 // indirect
+)

go.sum

@@ -0,0 +1,24 @@
+github.com/beorn7/perks v1.0.1 h1:VlbKKnNfV8bJzeqoa4cOKqO6bYr3WgKZxO8Z16+hsOM=
+github.com/beorn7/perks v1.0.1/go.mod h1:G2ZrVWU2WbWT9wwq4/hrbKbnv/1ERSJQ0ibhJ6rlkpw=
+github.com/cespare/xxhash/v2 v2.3.0 h1:UL815xU9SqsFlibzuggzjXhog7bL6oX9BbNZnL2UFvs=
+github.com/cespare/xxhash/v2 v2.3.0/go.mod h1:VGX0DQ3Q6kWi7AoAeZDth3/j3BFtOZR5XLFGgcrjCOs=
+github.com/google/go-cmp v0.6.0 h1:ofyhxvXcZhMsU5ulbFiLKl/XBFqE1GSq7atu8tAmTRI=
+github.com/google/go-cmp v0.6.0/go.mod h1:17dUlkBOakJ0+DkrSSNjCkIjxS6bF9zb3elmeNGIjoY=
+github.com/klauspost/compress v1.17.9 h1:6KIumPrER1LHsvBVuDa0r5xaG0Es51mhhB9BQB2qeMA=
+github.com/klauspost/compress v1.17.9/go.mod h1:Di0epgTjJY877eYKx5yC51cX2A2Vl2ibi7bDH9ttBbw=
+github.com/kylelemons/godebug v1.1.0 h1:RPNrshWIDI6G2gRW9EHilWtl7Z6Sb1BR0xunSBf0SNc=
+github.com/kylelemons/godebug v1.1.0/go.mod h1:9/0rRGxNHcop5bhtWyNeEfOS8JIWk580+fNqagV/RAw=
+github.com/munnerz/goautoneg v0.0.0-20191010083416-a7dc8b61c822 h1:C3w9PqII01/Oq1c1nUAm88MOHcQC9l5mIlSMApZMrHA=
+github.com/munnerz/goautoneg v0.0.0-20191010083416-a7dc8b61c822/go.mod h1:+n7T8mK8HuQTcFwEeznm/DIxMOiR9yIdICNftLE1DvQ=
+github.com/prometheus/client_golang v1.20.5 h1:cxppBPuYhUnsO6yo/aoRol4L7q7UFfdm+bR9r+8l63Y=
+github.com/prometheus/client_golang v1.20.5/go.mod h1:PIEt8X02hGcP8JWbeHyeZ53Y/jReSnHgO035n//V5WE=
+github.com/prometheus/client_model v0.6.1 h1:ZKSh/rekM+n3CeS952MLRAdFwIKqeY8b62p8ais2e9E=
+github.com/prometheus/client_model v0.6.1/go.mod h1:OrxVMOVHjw3lKMa8+x6HeMGkHMQyHDk9E3jmP2AmGiY=
+github.com/prometheus/common v0.55.0 h1:KEi6DK7lXW/m7Ig5i47x0vRzuBsHuvJdi5ee6Y3G1dc=
+github.com/prometheus/common v0.55.0/go.mod h1:2SECS4xJG1kd8XF9IcM1gMX6510RAEL65zxzNImwdc8=
+github.com/prometheus/procfs v0.15.1 h1:YagwOFzUgYfKKHX6Dr+sHT7km/hxC76UB0learggepc=
+github.com/prometheus/procfs v0.15.1/go.mod h1:fB45yRUv8NstnjriLhBQLuOUt+WW4BsoGhij/e3PBqk=
+golang.org/x/sys v0.22.0 h1:RI27ohtqKCnwULzJLqkv897zojh5/DwS/ENaMzUOaWI=
+golang.org/x/sys v0.22.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA=
+google.golang.org/protobuf v1.34.2 h1:6xV6lTsCfpGD21XK49h7MhtcApnLqkfYgPcdHftf6hg=
+google.golang.org/protobuf v1.34.2/go.mod h1:qYOHts0dSfpeUzUFpOMr/WGzszTmLH+DiWniOlNbLDw=

main.go

@@ -0,0 +1,219 @@
+package main
+
+import (
+	"bufio"
+	"context"
+	"encoding/json"
+	"flag"
+	"fmt"
+	"log"
+	"net/http"
+	"os"
+	"os/signal"
+	"path/filepath"
+	"strconv"
+	"strings"
+	"sync"
+	"syscall"
+	"time"
+
+	"github.com/prometheus/client_golang/prometheus"
+	"github.com/prometheus/client_golang/prometheus/promhttp"
+)
+
+type Config struct {
+	Repos          []string `json:"repos"`
+	IP             string   `json:"ip"`
+	Port           int      `json:"port"`
+	Endpoint       string   `json:"endpoint"`
+	TickerInterval int      `json:"ticker_interval"`
+}
+
+const (
+	defaultIP             = "0.0.0.0"
+	defaultPort           = 8080
+	defaultEndpoint       = "/metrics"
+	defaultTickerInterval = 60 // in seconds
+)
+
+var (
+	lastTransactionTimestamp = prometheus.NewGaugeVec(
+		prometheus.GaugeOpts{
+			Name: "borgbackup_last_transaction_timestamp",
+			Help: "Unix timestamp of the last transaction in the BorgBackup repository",
+		},
+		[]string{"repo"},
+	)
+	lastTransactionNumber = prometheus.NewGaugeVec(
+		prometheus.GaugeOpts{
+			Name: "borgbackup_last_transaction_number",
+			Help: "Number of the last transaction in the BorgBackup repository",
+		},
+		[]string{"repo"},
+	)
+)
+
+func init() {
+	prometheus.MustRegister(lastTransactionTimestamp)
+	prometheus.MustRegister(lastTransactionNumber)
+}
+
+func main() {
+	configPath := flag.String("config", "config.json", "Path to the configuration file")
+	flag.Parse()
+
+	config, err := loadConfig(*configPath)
+	if err != nil {
+		log.Fatalf("Failed to load configuration: %v", err)
+	}
+
+	applyDefaults(config)
+
+	ctx, cancel := context.WithCancel(context.Background())
+	defer cancel()
+
+	sigChan := make(chan os.Signal, 1)
+	signal.Notify(sigChan, os.Interrupt, syscall.SIGTERM)
+
+	var wg sync.WaitGroup
+
+	wg.Add(1)
+	go func() {
+		defer wg.Done()
+		updateMetricsLoop(ctx, config.Repos, time.Duration(config.TickerInterval)*time.Second)
+	}()
+
+	serverAddr := fmt.Sprintf("%s:%d", config.IP, config.Port)
+	http.Handle(config.Endpoint, promhttp.Handler())
+	server := &http.Server{Addr: serverAddr}
+
+	wg.Add(1)
+	go func() {
+		defer wg.Done()
+		log.Printf("Starting Prometheus exporter on %s%s\n", serverAddr, config.Endpoint)
+		if err := server.ListenAndServe(); err != nil && err != http.ErrServerClosed {
+			log.Printf("HTTP server error: %v", err)
+		}
+	}()
+
+	<-sigChan
+	log.Println("Received termination signal. Shutting down...")
+
+	cancel()
+
+	shutdownCtx, shutdownCancel := context.WithTimeout(context.Background(), 5*time.Second)
+	defer shutdownCancel()
+	if err := server.Shutdown(shutdownCtx); err != nil {
+		log.Printf("Error shutting down server: %v", err)
+	}
+
+	wg.Wait()
+	log.Println("Exporter stopped.")
+}
+
+func loadConfig(filename string) (*Config, error) {
+	file, err := os.Open(filename)
+	if err != nil {
+		return nil, err
+	}
+	defer file.Close()
+
+	var config Config
+	decoder := json.NewDecoder(file)
+	if err := decoder.Decode(&config); err != nil {
+		return nil, err
+	}
+
+	return &config, nil
+}
+
+func applyDefaults(config *Config) {
+	if config.IP == "" {
+		config.IP = defaultIP
+	}
+	if config.Port == 0 {
+		config.Port = defaultPort
+	}
+	if config.Endpoint == "" {
+		config.Endpoint = defaultEndpoint
+	}
+	if config.TickerInterval == 0 {
+		config.TickerInterval = defaultTickerInterval
+	}
+}
+
+func updateMetricsLoop(ctx context.Context, repos []string, interval time.Duration) {
+	ticker := time.NewTicker(interval)
+	defer ticker.Stop()
+
+  // Perform the first update immediately
+	for _, repo := range repos {
+		updateRepoMetrics(repo)
+	}
+
+	for {
+		select {
+		case <-ctx.Done():
+			log.Println("Stopping metrics update loop.")
+			return
+		case <-ticker.C:
+			for _, repo := range repos {
+				updateRepoMetrics(repo)
+			}
+		}
+	}
+}
+
+func updateRepoMetrics(repo string) {
+	transactionsFile := filepath.Join(repo, "transactions")
+	file, err := os.Open(transactionsFile)
+	if err != nil {
+		log.Printf("Failed to open transactions file for repo %s: %v", repo, err)
+		return
+	}
+	defer file.Close()
+
+	var lastLine string
+	scanner := bufio.NewScanner(file)
+	for scanner.Scan() {
+		lastLine = scanner.Text()
+	}
+
+	if err := scanner.Err(); err != nil {
+		log.Printf("Error reading transactions file for repo %s: %v", repo, err)
+		return
+	}
+
+  // instead of deferring as usual, close as soon as the 
+  file.Close()
+
+	transactionNumber, timestamp, err := parseTransactionLine(lastLine)
+	if err != nil {
+		log.Printf("Failed to parse transactions file for repo %s: %v", repo, err)
+		return
+	}
+
+	lastTransactionTimestamp.WithLabelValues(repo).Set(float64(timestamp))
+	lastTransactionNumber.WithLabelValues(repo).Set(float64(transactionNumber))
+}
+
+func parseTransactionLine(line string) (int, int64, error) {
+	parts := strings.Split(line, ",")
+	if len(parts) < 2 {
+		return 0, 0, fmt.Errorf("invalid line format: %s", line)
+	}
+
+	numberStr := strings.TrimPrefix(parts[0], "transaction ")
+	transactionNumber, err := strconv.Atoi(strings.TrimSpace(numberStr))
+	if err != nil {
+		return 0, 0, fmt.Errorf("failed to parse transaction number: %v", err)
+	}
+
+	timeStr := strings.TrimSpace(strings.Replace(parts[1], "UTC time", "", -1))
+	t, err := time.Parse("2006-01-02T15:04:05.000000", timeStr)
+	if err != nil {
+		return 0, 0, fmt.Errorf("failed to parse UTC time: %v", err)
+	}
+
+	return transactionNumber, t.Unix(), nil
+}