feat(embedded): add Perses + VictoriaMetrics subprocess management with auto-download

Ultraworked with [Sisyphus](https://github.com/code-yeongyu/claude-agent)

Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>

internal/embedded/perses.go

@@ -0,0 +1,149 @@
+package embedded
+
+import (
+	"fmt"
+	"os"
+	"os/exec"
+	"path/filepath"
+
+	"github.com/fujin/anthropic-proxy/internal/config"
+	"github.com/rs/zerolog/log"
+)
+
+type Perses struct {
+	cfg       config.EmbeddedConfig
+	proxyPort int
+	cmd       *exec.Cmd
+	tmpDir    string
+}
+
+func NewPerses(cfg config.EmbeddedConfig, proxyPort int) *Perses {
+	return &Perses{cfg: cfg, proxyPort: proxyPort}
+}
+
+func (p *Perses) Start() error {
+	bin, err := ensureBinary("perses", p.cfg.PersesBinary, p.cfg.BinDir)
+	if err != nil {
+		return fmt.Errorf("perses: %w", err)
+	}
+
+	p.tmpDir, err = os.MkdirTemp("", "perses-*")
+	if err != nil {
+		return fmt.Errorf("create temp dir: %w", err)
+	}
+
+	if err := p.writeServerConfig(); err != nil {
+		return fmt.Errorf("write server config: %w", err)
+	}
+	if err := p.writeDatasourceProvision(); err != nil {
+		return fmt.Errorf("write datasource provision: %w", err)
+	}
+	if err := p.writeDashboardProvision(); err != nil {
+		return fmt.Errorf("write dashboard provision: %w", err)
+	}
+
+	p.cmd = exec.Command(bin,
+		"--config", filepath.Join(p.tmpDir, "config.yaml"),
+		"-web.listen-address", fmt.Sprintf(":%d", p.cfg.Port),
+	)
+	p.cmd.Dir = filepath.Dir(bin)
+	p.cmd.Stdout = &logWriter{level: "info", component: "perses"}
+	p.cmd.Stderr = &logWriter{level: "error", component: "perses"}
+
+	if err := p.cmd.Start(); err != nil {
+		return fmt.Errorf("start perses: %w", err)
+	}
+
+	log.Info().
+		Str("binary", bin).
+		Int("port", p.cfg.Port).
+		Str("config", p.tmpDir).
+		Msg("perses started")
+
+	return nil
+}
+
+func (p *Perses) Stop() {
+	if p.cmd != nil && p.cmd.Process != nil {
+		_ = p.cmd.Process.Kill()
+		_ = p.cmd.Wait()
+	}
+	if p.tmpDir != "" {
+		_ = os.RemoveAll(p.tmpDir)
+	}
+}
+
+func (p *Perses) Running() bool {
+	return p.cmd != nil && p.cmd.Process != nil && p.cmd.ProcessState == nil
+}
+
+func (p *Perses) writeServerConfig() error {
+	provisionDir := filepath.Join(p.tmpDir, "provisions")
+	if err := os.MkdirAll(filepath.Join(provisionDir, "datasources"), 0o755); err != nil {
+		return err
+	}
+	if err := os.MkdirAll(filepath.Join(provisionDir, "dashboards"), 0o755); err != nil {
+		return err
+	}
+
+	cfg := fmt.Sprintf(`provisioning:
+  interval: 1m
+  folders:
+    - %s
+database:
+  file:
+    folder: %s/data
+    extension: json
+security:
+  readonly: false
+  enable_auth: false
+`, provisionDir, p.tmpDir)
+
+	return os.WriteFile(filepath.Join(p.tmpDir, "config.yaml"), []byte(cfg), 0o644)
+}
+
+func (p *Perses) writeDatasourceProvision() error {
+	ds := fmt.Sprintf(`kind: Datasource
+metadata:
+  name: victoria-metrics
+  project: anthropic-proxy
+spec:
+  default: true
+  plugin:
+    kind: PrometheusDatasource
+    spec:
+      directUrl: http://localhost:%d
+`, p.cfg.VMPort)
+
+	return os.WriteFile(
+		filepath.Join(p.tmpDir, "provisions", "datasources", "vm.yaml"),
+		[]byte(ds), 0o644,
+	)
+}
+
+func (p *Perses) writeDashboardProvision() error {
+	dashData, err := DashboardJSON()
+	if err != nil {
+		return err
+	}
+	return os.WriteFile(
+		filepath.Join(p.tmpDir, "provisions", "dashboards", "proxy.json"),
+		dashData, 0o644,
+	)
+}
+
+type logWriter struct {
+	level     string
+	component string
+}
+
+func (w *logWriter) Write(p []byte) (n int, err error) {
+	msg := string(p)
+	switch w.level {
+	case "error":
+		log.Error().Str("component", w.component).Msg(msg)
+	default:
+		log.Debug().Str("component", w.component).Msg(msg)
+	}
+	return len(p), nil
+}