Keep deployment logs findable after the container is recreated (closes #214)

Deployment logs were stored under a directory named after the container's hostname, and the path was worked out again from the current hostname on download. Docker gives a recreated container a new hostname, so every older log download returned 404. New logs now go to `logs/<appname>/` with no hostname in the path. Logs written by older versions under an old hostname directory are still found by looking one directory deeper, inside the same confined log root. Tests cover both the hostname-free path and downloading an old-layout log.

Model: opus-5-5

TODO.md

@@ -20,6 +20,10 @@ regress.
 
 # Completed Steps
 
+- 2026-09-23: Deployment log files are now stored under `logs/<appname>/`
+  instead of `logs/<hostname>/<appname>/`, so downloads keep working after the
+  upaas container is recreated; logs written under an old hostname directory are
+  still found (#214).
 - 2026-09-23: Fixed the flaky `t.TempDir` cleanup race in `internal/handlers`
   (the one fixed in `internal/service/webhook` by #198):
   `TestHandleWebhookProcessesValidWebhook` now waits with the webhook service's

internal/handlers/app.go

@@ -6,9 +6,11 @@ import (
 	"encoding/json"
 	"errors"
 	"fmt"
+	"io/fs"
 	"net/http"
 	"net/url"
 	"os"
+	"path"
 	"path/filepath"
 	"strconv"
 	"strings"
@@ -640,7 +642,7 @@ func (h *Handlers) HandleDeploymentLogDownload() http.HandlerFunc {
 		}
 		defer func() { _ = root.Close() }()
 
-		file, openErr := root.Open(relPath)
+		file, openErr := openDeploymentLog(root, relPath)
 		if openErr != nil {
 			http.NotFound(writer, request)
 
@@ -665,6 +667,24 @@ func (h *Handlers) HandleDeploymentLogDownload() http.HandlerFunc {
 	}
 }
 
+// openDeploymentLog opens a deployment log file inside the log root.
+// Logs written by older versions sit one directory deeper, under the
+// hostname of the container that wrote them, so when the file is not at
+// relPath it is looked for under any directory directly below the root.
+func openDeploymentLog(root *os.Root, relPath string) (*os.File, error) {
+	file, err := root.Open(relPath)
+	if err == nil {
+		return file, nil
+	}
+
+	matches, globErr := fs.Glob(root.FS(), path.Join("*", filepath.ToSlash(relPath)))
+	if globErr != nil || len(matches) == 0 {
+		return nil, err
+	}
+
+	return root.Open(matches[0])
+}
+
 // containerLogsAPITail is the default number of log lines for the container logs API.
 const containerLogsAPITail = "100"
 

internal/handlers/log_download_test.go

@@ -69,6 +69,56 @@ func TestHandleDeploymentLogDownloadServesLegitimateFile(t *testing.T) {
 	assert.Contains(t, recorder.Body.String(), "deploy log contents")
 }
 
+// TestGetLogFilePathHasNoHostname verifies a deployment log is stored
+// directly under logs/<appname>/, with no hostname directory in between,
+// so it is still found after the container is recreated with a new
+// hostname.
+func TestGetLogFilePathHasNoHostname(t *testing.T) {
+	t.Parallel()
+
+	testCtx := setupTestHandlers(t)
+	createdApp := createTestApp(t, testCtx, "log-path-app")
+
+	deployment := models.NewDeployment(testCtx.database)
+	deployment.AppID = createdApp.ID
+
+	logPath := testCtx.deploySvc.GetLogFilePath(createdApp, deployment)
+
+	assert.Equal(t,
+		filepath.Join(testCtx.deploySvc.GetLogDir(), createdApp.Name),
+		filepath.Dir(logPath),
+	)
+}
+
+// TestHandleDeploymentLogDownloadServesLogFromOldHostnameDir verifies a
+// log written by an older version, under the hostname of a container that
+// has since been recreated, can still be downloaded.
+func TestHandleDeploymentLogDownloadServesLogFromOldHostnameDir(t *testing.T) {
+	t.Parallel()
+
+	testCtx := setupTestHandlers(t)
+	createdApp := createTestApp(t, testCtx, "log-old-hostname-app")
+
+	deployment := models.NewDeployment(testCtx.database)
+	deployment.AppID = createdApp.ID
+	deployment.Status = models.DeploymentStatusSuccess
+	require.NoError(t, deployment.Save(context.Background()))
+
+	logDir := testCtx.deploySvc.GetLogDir()
+	newPath := testCtx.deploySvc.GetLogFilePath(createdApp, deployment)
+	relPath, relErr := filepath.Rel(logDir, newPath)
+	require.NoError(t, relErr)
+
+	oldPath := filepath.Join(logDir, "old-container-hostname", relPath)
+	require.NoError(t, os.MkdirAll(filepath.Dir(oldPath), 0o750))
+	require.NoError(t, os.WriteFile(oldPath, []byte("old deploy log contents"), 0o600))
+
+	recorder := doLogDownload(t, testCtx, createdApp.ID, deployment.ID)
+
+	assert.Equal(t, http.StatusOK, recorder.Code)
+	assert.Contains(t, recorder.Body.String(), "old deploy log contents")
+}
+
 // TestHandleDeploymentLogDownloadRejectsPathTraversal verifies the
 // os.Root containment guard. A traversal-shaped app name drives the
 // resolved log path out of the deploy log directory onto a sentinel

internal/service/deploy/deploy.go

@@ -261,15 +261,14 @@ func (svc *Service) GetBuildDir(appName string) string {
 
 // GetLogFilePath returns the path to the log file for a deployment.
 // Returns empty string if the path cannot be determined.
+//
+// The path must not depend on the container's hostname: Docker assigns a
+// new one whenever the container is recreated, and older logs would then
+// no longer be found.
 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 != "" {
@@ -291,7 +290,7 @@ func (svc *Service) GetLogFilePath(
 		filename = fmt.Sprintf("%s_%s.log.txt", app.Name, timestamp)
 	}
 
-	return filepath.Join(svc.config.DataDir, "logs", hostname, app.Name, filename)
+	return filepath.Join(svc.config.DataDir, "logs", app.Name, filename)
 }
 
 // GetLogDir returns the root directory under which all deployment log
@@ -1294,7 +1293,7 @@ func (svc *Service) failDeployment(
 }
 
 // writeLogsToFile writes the deployment logs to a file on disk.
-// Structure: DataDir/logs/<hostname>/<appname>/<appname>_<sha>_<timestamp>.log.txt
+// Structure: DataDir/logs/<appname>/<appname>_<sha>_<timestamp>.log.txt
 func (svc *Service) writeLogsToFile(app *models.App, deployment *models.Deployment) {
 	if !deployment.Logs.Valid || deployment.Logs.String == "" {
 		return