> ## Documentation Index > Fetch the complete documentation index at: https://docs.tensorlake.ai/llms.txt > Use this file to discover all available pages before exploring further. # Attach Filesystem > Attach a filesystem to a running sandbox at an absolute guest mount path. Returns `200 OK` once the mount is persisted; the mount applies asynchronously on the live sandbox. If the mount later cannot converge — including a `file_system_id` that does not exist — the sandbox is terminated fail-closed with `termination_reason` and `error_details` on the sandbox object, so verify the filesystem exists (for example with `tl fs ls`) before attaching. Attach a [filesystem](/sandboxes/mount-filesystems) to a running sandbox at an absolute guest mount path. * This path accepts either the sandbox ID or the sandbox name. * `file_system_id` is the filesystem's name — the one created with `tl fs create `. * `200 OK` means the mount is persisted; it applies asynchronously on the live sandbox moments later. * If the mount later cannot converge — including a filesystem that does not exist — the sandbox is terminated fail-closed with `termination_reason` and `error_details` on the sandbox object. Verify the filesystem exists (e.g. `tl fs ls`) before attaching. * Tensorlake returns `400 Bad Request` when the sandbox runs on an executor fleet without filesystem support. * Tensorlake returns `409 Conflict` when the sandbox is not running, the mount path is already in use, the sandbox is at the 8-mount cap, or the sandbox's executor is momentarily unresolvable. The last case is transient — retry shortly. ## OpenAPI ````yaml post /sandboxes/{sandbox_id}/file_systems openapi: 3.1.0 info: title: Tensorlake API description: >- Tensorlake Cloud APIs for Sandboxes, Document Ingestion, and Serverless Workflows license: name: '' version: 0.1.0 servers: - url: https://api.tensorlake.ai/ security: - bearerAuth: [] tags: - name: Tensorlake Cloud API description: >- Tensorlake Cloud APIs for Sandboxes, Document Ingestion, and Serverless Workflows paths: /sandboxes/{sandbox_id}/file_systems: parameters: - name: sandbox_id in: path description: The sandbox ID or sandbox name. required: true schema: type: string post: tags: - sandboxes summary: Attach a filesystem description: >- Attach a filesystem to a running sandbox at an absolute guest mount path. Returns `200 OK` once the mount is persisted; the mount applies asynchronously on the live sandbox. If the mount later cannot converge — including a `file_system_id` that does not exist — the sandbox is terminated fail-closed with `termination_reason` and `error_details` on the sandbox object, so verify the filesystem exists (for example with `tl fs ls`) before attaching. operationId: attach_file_system requestBody: content: application/json: schema: $ref: '#/components/schemas/FileSystemMount' required: true responses: '200': description: >- Filesystem attach accepted and persisted; the returned sandbox already reflects the new `file_systems` entry content: application/json: schema: $ref: '#/components/schemas/SandboxInfo' '400': description: >- Invalid mount, or the sandbox runs on an executor fleet without filesystem support content: text/plain: {} '401': description: Unauthorized. Invalid or missing credentials '403': description: Forbidden. You do not have permission to access this resource '404': description: Sandbox not found content: text/plain: {} '409': description: >- Sandbox not running, mount path already in use or at the mount cap, or the sandbox's executor is momentarily unresolvable (transient — retry shortly) content: text/plain: {} '500': description: Internal server error content: text/plain: {} components: schemas: FileSystemMount: type: object required: - file_system_id - mount_path properties: file_system_id: type: string description: >- Filesystem name within the project — the name created with `tl fs create `. ASCII letters, digits, `_`, and `-` only. mount_path: type: string description: >- Absolute guest mount path (e.g. `/mnt/skills`). Must not be `/` or contain `..`; paths are normalized, and mount paths must be unique and non-nested within the sandbox. read_only: type: boolean default: false description: >- Mount the filesystem read-only. Writes inside the guest fail with `EROFS`; the mount's storage credential carries no write scope. Fail-closed — sandboxes requesting read-only mounts are only placed on fleets that can enforce them. prefetch: type: boolean default: false description: >- Download the filesystem's full tree in the background after the mount is ready. The mount is usable immediately with lazy reads meanwhile. Best-effort — never blocks or fails the sandbox, and older fleets skip it silently. SandboxInfo: type: object required: - id - namespace - status - created_at - resources - timeout_secs - allow_unauthenticated_access properties: id: type: string namespace: type: string image: type: string status: $ref: '#/components/schemas/SandboxStatus' pending_reason: type: - string - 'null' description: Present when `status` is `pending`. outcome: type: - string - 'null' description: >- Platform-specific termination outcome string returned for completed sandboxes. termination_reason: type: - string - 'null' description: >- Typed reason the sandbox terminated (e.g. `FileSystemNotFound`, `ImageNotFound`). Present on failed terminations. error_details: type: - string - 'null' description: Human-readable detail accompanying `termination_reason`. created_at: type: integer format: int64 description: Milliseconds since Unix epoch. container_id: type: - string - 'null' executor_id: type: - string - 'null' resources: $ref: '#/components/schemas/ContainerResourcesInfo' timeout_secs: type: integer format: int64 ingress_endpoint: type: - string - 'null' description: Canonical server-provided base for sandbox-specific ingress. sandbox_url: type: - string - 'null' description: Sandbox-specific management URL derived from `ingress_endpoint`. pool_id: type: - string - 'null' network_policy: oneOf: - type: 'null' - $ref: '#/components/schemas/SandboxNetworkAccessControl' allow_unauthenticated_access: type: boolean description: Whether sandbox ingress may route requests without auth validation. exposed_ports: type: - array - 'null' items: type: integer format: int32 minimum: 1 maximum: 65535 description: >- Additional routable ingress ports. When `null`, only the management port `9501` is routable. template_id: type: - string - 'null' name: type: - string - 'null' file_systems: type: array description: Filesystems currently mounted into the sandbox. items: $ref: '#/components/schemas/FileSystemMount' SandboxStatus: type: string enum: - pending - running - snapshotting - suspending - suspended - terminated ContainerResourcesInfo: type: object required: - cpus - memory_mb - disk_mb properties: cpus: type: number format: double description: CPU allocation in cores. memory_mb: type: integer format: int64 description: Memory allocation in MiB. disk_mb: type: integer format: int64 description: Ephemeral root filesystem size in MiB. SandboxNetworkAccessControl: type: object properties: allow_internet_access: type: boolean default: true description: >- Allows internet access, including DNS requests. If false, all outbound traffic except destinations in allow_out is blocked, including DNS requests. If allow_out is non-empty and this is true, only the listed destinations and DNS requests are allowed. allow_out: type: array description: >- Allowed domains, IPv4 addresses, or IPv4 CIDRs. A non-empty list allows the listed destinations and DNS requests when allow_internet_access is true. Hostname rules are followed across DNS changes. A destination also matched by deny_out is blocked. items: type: string deny_out: type: array description: >- Denied domains, IPv4 addresses, or IPv4 CIDRs. Takes precedence over allow_out; a destination matched by both is blocked. items: type: string securitySchemes: bearerAuth: type: http scheme: bearer ````