Add build log file storage and download functionality

- Write deployment logs to files when deployment finishes (success or failure)
- Log files stored in DataDir/logs/<hostname>/<appname>/<appname>_<sha>_<timestamp>.log.txt
- Capture commit SHA for manual deploys by parsing git rev-parse HEAD after clone
- Add download endpoint for log files at /apps/{id}/deployments/{deploymentID}/download
- Add download link in deployment history view for finished deployments

internal/service/deploy/deploy.go

@@ -52,6 +52,18 @@ var (
 // logFlushInterval is how often to flush buffered logs to the database.
 const logFlushInterval = time.Second
 
+// logsDirPermissions is the permission mode for the logs directory.
+const logsDirPermissions = 0o750
+
+// logFilePermissions is the permission mode for log files.
+const logFilePermissions = 0o640
+
+// logTimestampFormat is the format for log file timestamps.
+const logTimestampFormat = "20060102T150405Z"
+
+// logFileShortSHALength is the number of characters to use for commit SHA in log filenames.
+const logFileShortSHALength = 12
+
 // dockerLogMessage represents a Docker build log message.
 type dockerLogMessage struct {
 	Stream string `json:"stream"`
@@ -225,6 +237,37 @@ func (svc *Service) GetBuildDir(appID string) string {
 	return filepath.Join(svc.config.DataDir, "builds", appID)
 }
 
+// GetLogFilePath returns the path to the log file for a deployment.
+// Returns empty string if the path cannot be determined.
+func (svc *Service) GetLogFilePath(app *models.App, deployment *models.Deployment) string {
+	hostname, err := os.Hostname()
+	if err != nil {
+		hostname = "unknown"
+	}
+
+	// Get commit SHA
+	sha := ""
+	if deployment.CommitSHA.Valid && deployment.CommitSHA.String != "" {
+		sha = deployment.CommitSHA.String
+		if len(sha) > logFileShortSHALength {
+			sha = sha[:logFileShortSHALength]
+		}
+	}
+
+	// Use started_at timestamp
+	timestamp := deployment.StartedAt.UTC().Format(logTimestampFormat)
+
+	// Build filename: appname_sha_timestamp.log.txt (or appname_timestamp.log.txt if no SHA)
+	var filename string
+	if sha != "" {
+		filename = fmt.Sprintf("%s_%s_%s.log.txt", app.Name, sha, timestamp)
+	} else {
+		filename = fmt.Sprintf("%s_%s.log.txt", app.Name, timestamp)
+	}
+
+	return filepath.Join(svc.config.DataDir, "logs", hostname, app.Name, filename)
+}
+
 // Deploy deploys an app.
 func (svc *Service) Deploy(
 	ctx context.Context,
@@ -575,9 +618,37 @@ func (svc *Service) cloneRepository(
 		return "", nil, fmt.Errorf("failed to clone repo: %w", cloneErr)
 	}
 
+	svc.processCloneResult(ctx, app, deployment, cloneResult, commitSHA)
+
+	// Return the 'work' subdirectory where the repo was cloned
+	workDir := filepath.Join(buildDir, "work")
+
+	return workDir, cleanup, nil
+}
+
+// processCloneResult handles the result of a git clone operation.
+// It sets the commit SHA on the deployment if not already set, and logs the result.
+func (svc *Service) processCloneResult(
+	ctx context.Context,
+	app *models.App,
+	deployment *models.Deployment,
+	cloneResult *docker.CloneResult,
+	originalCommitSHA string,
+) {
+	// Set commit SHA from clone result if not already set (e.g., manual deploys)
+	if cloneResult != nil && cloneResult.CommitSHA != "" && !deployment.CommitSHA.Valid {
+		deployment.CommitSHA = sql.NullString{String: cloneResult.CommitSHA, Valid: true}
+		_ = deployment.Save(ctx)
+	}
+
 	// Log clone success with git output
-	if commitSHA != "" {
-		_ = deployment.AppendLog(ctx, "Repository cloned at commit "+commitSHA)
+	actualCommitSHA := originalCommitSHA
+	if cloneResult != nil && cloneResult.CommitSHA != "" {
+		actualCommitSHA = cloneResult.CommitSHA
+	}
+
+	if actualCommitSHA != "" {
+		_ = deployment.AppendLog(ctx, "Repository cloned at commit "+actualCommitSHA)
 	} else {
 		_ = deployment.AppendLog(ctx, "Repository cloned (branch: "+app.Branch+")")
 	}
@@ -585,11 +656,6 @@ func (svc *Service) cloneRepository(
 	if cloneResult != nil && cloneResult.Output != "" {
 		_ = deployment.AppendLog(ctx, cloneResult.Output)
 	}
-
-	// Return the 'work' subdirectory where the repo was cloned
-	workDir := filepath.Join(buildDir, "work")
-
-	return workDir, cleanup, nil
 }
 
 // containerToHostPath converts a container-local path to the equivalent host path.
@@ -835,6 +901,7 @@ func (svc *Service) checkHealthAfterDelay(
 		svc.log.Info("container healthy after 60 seconds", "app", reloadedApp.Name)
 		svc.notify.NotifyDeploySuccess(ctx, reloadedApp, deployment)
 		_ = deployment.MarkFinished(ctx, models.DeploymentStatusSuccess)
+		svc.writeLogsToFile(reloadedApp, deployment)
 	} else {
 		svc.log.Warn(
 			"container unhealthy after 60 seconds",
@@ -842,6 +909,7 @@ func (svc *Service) checkHealthAfterDelay(
 		)
 		svc.notify.NotifyDeployFailed(ctx, reloadedApp, deployment, ErrContainerUnhealthy)
 		_ = deployment.MarkFinished(ctx, models.DeploymentStatusFailed)
+		svc.writeLogsToFile(reloadedApp, deployment)
 		reloadedApp.Status = models.AppStatusError
 		_ = reloadedApp.Save(ctx)
 	}
@@ -856,6 +924,39 @@ func (svc *Service) failDeployment(
 	svc.log.Error("deployment failed", "app", app.Name, "error", deployErr)
 	_ = deployment.AppendLog(ctx, "ERROR: "+deployErr.Error())
 	_ = deployment.MarkFinished(ctx, models.DeploymentStatusFailed)
+	svc.writeLogsToFile(app, deployment)
 	app.Status = models.AppStatusError
 	_ = app.Save(ctx)
 }
+
+// writeLogsToFile writes the deployment logs to a file on disk.
+// Structure: DataDir/logs/<hostname>/<appname>/<appname>_<sha>_<timestamp>.log.txt
+func (svc *Service) writeLogsToFile(app *models.App, deployment *models.Deployment) {
+	if !deployment.Logs.Valid || deployment.Logs.String == "" {
+		return
+	}
+
+	logPath := svc.GetLogFilePath(app, deployment)
+	if logPath == "" {
+		return
+	}
+
+	// Ensure directory exists
+	logDir := filepath.Dir(logPath)
+
+	err := os.MkdirAll(logDir, logsDirPermissions)
+	if err != nil {
+		svc.log.Error("failed to create logs directory", "error", err, "path", logDir)
+
+		return
+	}
+
+	err = os.WriteFile(logPath, []byte(deployment.Logs.String), logFilePermissions)
+	if err != nil {
+		svc.log.Error("failed to write log file", "error", err, "path", logPath)
+
+		return
+	}
+
+	svc.log.Info("wrote deployment logs to file", "path", logPath)
+}