Mount Folders and Data

Host mounts let a sandbox read files from your local machine without copying them. This is useful when an agent needs to explore a codebase or process data that already lives on your host. By default, the host folder is read-only — the sandbox can read every file, but changes stay inside the sandbox and never touch the originals. If you need the sandbox to write back to the host, see writable mounts below.

CLI

Mount a directory when creating a sandbox:

celesto sandbox create --mount ~/Projects/my-app
celesto sandbox ssh my-sandbox
ls /workspace   # your host files appear here

Mount multiple directories at custom paths:

celesto sandbox create --mount ~/Projects/my-app:/code --mount ~/data:/mnt/data

Python SDK

from celesto import Celesto

with Celesto(mounts=["~/Projects/my-app"]) as vm:
    result = vm.run("ls /workspace")
    print(result.stdout)

You can also specify custom mount paths:

with Celesto(mounts=["~/Projects/my-app:/code", "~/data:/mnt/data"]) as vm:
    result = vm.run("ls /code")
    print(result.stdout)

Writable mounts

By default, mounts are read-only. Add --writable-mounts to let the sandbox write back to your host directories.

CLI

celesto sandbox create --mount ~/Projects/my-app --writable-mounts

Any file the sandbox creates or modifies inside the mount point appears on your host immediately.

Python SDK

from celesto import Celesto

with Celesto(mounts=["~/Projects/my-app"], writable_mounts=True) as vm:
    vm.run("echo 'hello' > /workspace/new-file.txt")
    # new-file.txt now exists on the host at ~/Projects/my-app/new-file.txt

Writable mounts give the sandbox full write access to the mounted host directories. Make sure you trust the code running inside the sandbox before enabling this flag.

Last modified on November 5, 2026

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Mount Folders and Data

CLI

Python SDK

Writable mounts

CLI

Python SDK

​CLI

​Python SDK

​Writable mounts

​CLI

​Python SDK

CLI

Python SDK

Writable mounts

CLI

Python SDK