fix(db): Dowload database when missing but metadata still exists

pkg/db/db.go

@@ -110,21 +110,26 @@ func (c *Client) NeedsUpdate(ctx context.Context, cliVersion string, skip bool)
 		meta = metadata.Metadata{Version: db.SchemaVersion}
 	}
 
+	// We can't use the DB if either `trivy.db` or `metadata.json` is missing.
+	// In that case, we need to download the DB.
+	if noRequiredFiles {
+		if skip {
+			log.ErrorContext(ctx, "The first run cannot skip downloading DB")
+			return false, xerrors.New("--skip-db-update cannot be specified on the first run")
+		}
+		return true, nil
+	}
+
 	// There are 3 cases when DownloadAt field is zero:
 	// - metadata file was not created yet. This is the first run of Trivy.
 	// - trivy-db was downloaded with `oras`. In this case user can use `--skip-db-update` (like for air-gapped) or re-download trivy-db.
 	// - trivy-db was corrupted while copying from tmp directory to cache directory. We should update this trivy-db.
 	// We can't detect these cases, so we will show warning for users who use oras + air-gapped.
-	if !noRequiredFiles && meta.DownloadedAt.IsZero() && !skip {
+	if meta.DownloadedAt.IsZero() && !skip {
 		log.WarnContext(ctx, "Trivy DB may be corrupted and will be re-downloaded. If you manually downloaded DB - use the `--skip-db-update` flag to skip updating DB.")
 		return true, nil
 	}
 
-	if skip && noRequiredFiles {
-		log.ErrorContext(ctx, "The first run cannot skip downloading DB")
-		return false, xerrors.New("--skip-db-update cannot be specified on the first run")
-	}
-
 	if db.SchemaVersion < meta.Version {
 		log.ErrorContext(ctx, "Trivy version is old. Update to the latest version.", log.String("version", cliVersion))
 		return false, xerrors.Errorf("the version of DB schema doesn't match. Local DB: %d, Expected: %d",

pkg/db/db_test.go

@@ -219,6 +219,19 @@ func TestClient_NeedsUpdate(t *testing.T) {
 				"The local DB has an old schema version which is not supported by the current version of Trivy CLI. DB needs to be updated.",
 			},
 		},
+		{
+			name:         "trivy.db is missing but metadata with recent DownloadedAt",
+			dbFileExists: false,
+			metadata: metadata.Metadata{
+				Version:      db.SchemaVersion,
+				NextUpdate:   timeNextUpdateDay1,
+				DownloadedAt: time.Date(2019, 9, 30, 23, 30, 0, 0, time.UTC),
+			},
+			want: true,
+			wantLogs: []string{
+				"There is no db file",
+			},
+		},
 	}
 
 	for _, tt := range tests {