Scenario:

You have a container image myapp:fs built from /home/interview/Dockerfile that performs intensive filesystem write operations. Docker is currently using the overlayfs storage driver and write performance is a bottleneck.

Task:

Configure Docker deamon /etc/docker/daemon.json to use appropriate configuration for write heavy setup. Restart the Docker daemon, and rebuild the myapp:fs image for validation testing.

Step 1: Check current storage driver

docker info | grep "Storage Driver"

Should show overlay2 or the current driver.

Step 2: Verify fuse-overlayfs is installed

which fuse-overlayfs

Should show the binary path. fuse-overlayfs uses FUSE (Filesystem in Userspace) for overlay mounts.

Step 3: Edit Docker daemon configuration

sudo nano /etc/docker/daemon.json

Add "storage-driver": "fuse-overlayfs" to the JSON. Ensure proper JSON syntax with commas between key-value pairs:

{
  ... // current config
  "storage-driver": "fuse-overlayfs"
}

If adding to existing settings, add a comma after the previous setting.

Step 4: Restart Docker daemon

sudo systemctl restart docker

Applies the new storage driver. Existing images may not be accessible after changing drivers.

Step 5: Verify the new storage driver

docker info | grep "Storage Driver"

Should now show fuse-overlayfs.

Step 6: Rebuild the image

docker build -t myapp:fs .

Rebuilds using fuse-overlayfs storage.

Step 7: Test container functionality

docker run --rm myapp:fs echo "Test"

Verifies basic functionality works.