break: take --repos-dir instead of --repos

Because I want to be able to configure which repos are exported
in the repo configs, which is implemented in the next commit.

3 files changed, 45 insertions, 21 deletions

diff --git a/main.go b/main.go
index 2e0e2cc..66a4b2c 100644
--- a/main.go
+++ b/main.go
@@ -10,6 +10,7 @@ import (
 	"net/http"
 	"os"
 	"os/exec"
+	"path"
 	"regexp"
 	"slices"
 	"strings"
@@ -21,7 +22,7 @@ import (
 
 type Args struct {
 	Port     int       `help:"Port to listen on" short:"p" default:"8888" env:"PORT"`
-	Repos    StringMap `placeholder:"{\"name\": \"path\", ...}" required:"" help:"Repositories to be grepped" env:"REPOS"`
+	ReposDir string    `required:"" help:"Directory containing repositories to be grepped" env:"REPOS_DIR"`
 	Patterns StringMap `placeholder:"{\"name\": \"regex\", ...}" required:"" help:"Patterns to be grepped for" env:"PATTERNS"`
 }
 
@@ -40,32 +41,29 @@ func main() {
 
 	var args Args
 	ctx := kong.Parse(&args, kong.Description(
-		"Prometheus metrics for how many lines in certain git repos match certain regular expressions.\n\n"+
+		"Prometheus metrics for how many lines in git repos match certain regular expressions.\n\n"+
 			"Only the HEAD of the repositories will be grepped.",
 	))
 
-	te, err := newGitGrepExporter(args.Repos, args.Patterns, prometheus.DefaultRegisterer)
+	te, err := newGitGrepExporter(args.ReposDir, args.Patterns, prometheus.DefaultRegisterer)
 	ctx.FatalIfErrorf(err)
 
 	prometheus.MustRegister(te)
 	http.Handle("/metrics", promhttp.Handler())
 
-	slog.Info("starting", "repos", args.Repos, "patterns", args.Patterns)
+	slog.Info("starting", "reposDir", args.ReposDir, "patterns", args.Patterns)
 	slog.Info(fmt.Sprintf("serving metrics at http://localhost:%d/metrics", args.Port))
 	http.ListenAndServe(fmt.Sprintf(":%d", args.Port), nil)
 }
 
 type GitGrepExporter struct {
-	repos           map[string]string
+	reposDir        string
 	descs           map[string]*prometheus.Desc
 	regexes         map[string]*regexp.Regexp
 	combinedPattern string
 }
 
-func newGitGrepExporter(repos map[string]string, patterns map[string]string, reg prometheus.Registerer) (*GitGrepExporter, error) {
-	if len(repos) == 0 {
-		return nil, fmt.Errorf("no repositories specified")
-	}
+func newGitGrepExporter(reposDir string, patterns map[string]string, reg prometheus.Registerer) (*GitGrepExporter, error) {
 	if len(patterns) == 0 {
 		return nil, fmt.Errorf("no patterns specified")
 	}
@@ -83,7 +81,7 @@ func newGitGrepExporter(repos map[string]string, patterns map[string]string, reg
 		regexes[name] = regexp.MustCompile(pattern)
 	}
 
-	return &GitGrepExporter{repos, descs, regexes, strings.Join(slices.Collect(maps.Values(patterns)), "|")}, nil
+	return &GitGrepExporter{reposDir, descs, regexes, strings.Join(slices.Collect(maps.Values(patterns)), "|")}, nil
 }
 
 func (e *GitGrepExporter) Describe(ch chan<- *prometheus.Desc) {
@@ -93,15 +91,34 @@ func (e *GitGrepExporter) Describe(ch chan<- *prometheus.Desc) {
 }
 
 func (g *GitGrepExporter) Collect(ch chan<- prometheus.Metric) {
-	for name, path := range g.repos {
-		slog.Info("starting grep", "path", path)
-		g.collectCountsForRepo(name, ch)
-		slog.Info("finished grep", "path", path)
+	slog.Info("listing directory", "path", g.reposDir)
+	entries, err := os.ReadDir(g.reposDir)
+	if err != nil {
+		slog.Error("failed to read repos directory", "path", g.reposDir, "error", err)
+		for _, desc := range g.descs {
+			ch <- prometheus.NewInvalidMetric(desc, err)
+		}
+		return
+	}
+
+	for _, entry := range entries {
+		if !entry.IsDir() {
+			continue
+		}
+		repoPath := path.Join(g.reposDir, entry.Name())
+		logger := slog.With("path", repoPath)
+
+		logger.Info("starting grep")
+		g.collectCountsForRepo(entry.Name(), repoPath, ch)
+		if err != nil {
+			logger.Error("grep failed", "error", err)
+			continue
+		}
+		logger.Info("finished grep")
 	}
 }
 
-func (g *GitGrepExporter) collectCountsForRepo(repo string, ch chan<- prometheus.Metric) {
-	path := g.repos[repo]
+func (g *GitGrepExporter) collectCountsForRepo(repo string, path string, ch chan<- prometheus.Metric) {
 	output, err := run("git", "-C", path, "grep", "-hE", g.combinedPattern, "HEAD")
 
 	if err != nil {
diff --git a/main_test.go b/main_test.go
index 9fdecca..45a3ba5 100644
--- a/main_test.go
+++ b/main_test.go
@@ -2,6 +2,8 @@ package main
 
 import (
 	"log"
+	"os"
+	"path"
 	"strings"
 	"testing"
 
@@ -11,10 +13,15 @@ import (
 )
 
 func TestGrepRepo(t *testing.T) {
-	repos := map[string]string{"project1": "/srv/repos/project1"}
+	reposDir := t.TempDir()
+	err := os.Mkdir(path.Join(reposDir, "project1"), 0o755)
+	if err != nil {
+		t.Fatal(err)
+	}
+
 	patterns := map[string]string{"match": "\\bMATCH\\b", "match_start": "^MATCH"}
 	reg := prometheus.NewRegistry()
-	te, err := newGitGrepExporter(repos, patterns, reg)
+	te, err := newGitGrepExporter(reposDir, patterns, reg)
 	if err != nil {
 		t.Fatal(err)
 	}
diff --git a/service.nix b/service.nix
index bc0bbdc..ba53972 100644
--- a/service.nix
+++ b/service.nix
@@ -16,8 +16,8 @@ in
       type = lib.types.attrsOf lib.types.str;
     };
 
-    repos = lib.mkOption {
-      type = lib.types.attrsOf lib.types.str;
+    reposDir = lib.mkOption {
+      type = lib.types.str;
     };
 
     extraGroups = lib.mkOption {
@@ -35,7 +35,7 @@ in
       };
       environment = {
         PORT = toString cfg.port;
-        REPOS = builtins.toJSON cfg.repos;
+        REPOS_DIR = cfg.reposDir;
         PATTERNS = builtins.toJSON cfg.patterns;
       };