fix: log containerbaseDir (#17509)

lib/util/exec/docker/index.ts

@@ -232,8 +232,15 @@ export async function generateDockerCommand(
   }
 
   const volumeDirs: VolumeOption[] = [localDir, cacheDir];
-  if (containerbaseDir && cacheDir && !containerbaseDir.startsWith(cacheDir)) {
-    volumeDirs.push(containerbaseDir);
+  if (containerbaseDir) {
+    if (cacheDir && containerbaseDir.startsWith(cacheDir)) {
+      logger.debug('containerbaseDir is inside cacheDir');
+    } else {
+      logger.debug('containerbaseDir is separate from cacheDir');
+      volumeDirs.push(containerbaseDir);
+    }
+  } else {
+    logger.debug('containerbaseDir is missing');
   }
   volumeDirs.push(...volumes);
   result.push(...prepareVolumes(volumeDirs));

lib/util/exec/index.ts

@@ -105,6 +105,7 @@ async function prepareRawExec(
     GlobalConfig.get();
 
   if (binarySource === 'docker' || binarySource === 'install') {
+    logger.debug(`Setting BUILDPACK_CACHE_DIR to ${containerbaseDir!}`);
     opts.env ??= {};
     opts.env.BUILDPACK_CACHE_DIR = containerbaseDir;
   }