> ## Documentation Index > Fetch the complete documentation index at: https://sandbox-docs.thundercompute.com/llms.txt > Use this file to discover all available pages before exploring further. # Start a sandbox > Creates an immutable sandbox and returns as soon as startup is accepted. Poll the returned ID until its status is running or failed. ## OpenAPI ````yaml /api-reference/openapi.yaml post /sandboxes/start openapi: 3.1.0 info: title: Thunder Sandbox API version: '1.0' description: Create, inspect, list, and stop Thunder sandboxes. contact: name: Thunder Compute Support url: https://www.thundercompute.com/contact email: support@thundercompute.com servers: - url: https://api.thundercompute.com:8443/v1 description: Production security: - bearerAuth: [] tags: - name: Sandboxes description: Short-lived isolated compute environments. paths: /sandboxes/start: post: tags: - Sandboxes summary: Start a sandbox description: >- Creates an immutable sandbox and returns as soon as startup is accepted. Poll the returned ID until its status is running or failed. operationId: startSandbox requestBody: required: true description: >- Resources, lifetime, network policy, environment, and immutable SSH key. content: application/json: schema: $ref: '#/components/schemas/SandboxStartRequest' example: name: training-run spec: cpu_count: 4 memory_gib: 32 storage_gib: 50 gpu_type: H100 gpu_count: 1 env: RUN_ID: '42' lifetime: enforce_ttl: true max_ttl_seconds: 3600 network_policy: internet_access: open ssh_public_key: ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAIExampleReplaceWithYourKey responses: '202': description: Startup accepted. content: application/json: schema: $ref: '#/components/schemas/SandboxStartResponse' example: id: sbx-0123456789abcdef name: training-run '400': $ref: '#/components/responses/BadRequest' '401': $ref: '#/components/responses/Unauthorized' '403': $ref: '#/components/responses/Forbidden' '409': $ref: '#/components/responses/Conflict' '429': $ref: '#/components/responses/TooManyRequests' '500': $ref: '#/components/responses/InternalError' '503': $ref: '#/components/responses/Unavailable' '504': $ref: '#/components/responses/GatewayTimeout' components: schemas: SandboxStartRequest: type: object required: - spec - lifetime - network_policy - ssh_public_key properties: name: type: string maxLength: 64 description: >- Optional display label. It must be unique among live sandboxes and cannot be used in place of the ID. It must be printable, have no leading or trailing whitespace or slash, and cannot be ., .., or a value surrounded by double underscores. spec: $ref: '#/components/schemas/SandboxResourceSpec' env: type: object description: Environment variables installed for SSH sessions. propertyNames: pattern: ^[A-Za-z_][A-Za-z0-9_]*$ additionalProperties: type: string lifetime: $ref: '#/components/schemas/SandboxLifetime' network_policy: $ref: '#/components/schemas/SandboxNetworkPolicy' ssh_public_key: type: string description: One-line OpenSSH public key. It cannot be replaced after creation. SandboxStartResponse: type: object required: - id - name properties: id: type: string description: Permanent identifier for every later request. example: sbx-0123456789abcdef name: type: string description: Display label, or the ID when no name was supplied. example: training-run SandboxResourceSpec: type: object required: - cpu_count - memory_gib - storage_gib description: >- GPU type and count must be supplied together. Supported types and ranges depend on the organization's sandbox configuration. properties: cpu_count: type: integer format: uint32 minimum: 1 description: Number of vCPUs. memory_gib: type: integer format: uint32 minimum: 1 description: Memory in GiB. storage_gib: type: integer format: uint32 minimum: 1 description: Ephemeral disk size in GiB. gpu_type: type: string description: GPU type such as H100. Omit with gpu_count for CPU-only. gpu_count: type: integer format: uint32 minimum: 1 description: Number of GPUs. Supply together with gpu_type. SandboxLifetime: type: object required: - enforce_ttl properties: enforce_ttl: type: boolean description: Whether Thunder automatically stops the sandbox. max_ttl_seconds: type: integer format: uint32 minimum: 0 description: >- Lifetime from creation in seconds. Use a positive value when enforce_ttl is true. max_grace_seconds: type: integer format: uint32 minimum: 0 description: >- Requested graceful-shutdown budget in seconds; the platform may enforce a lower limit. SandboxNetworkPolicy: type: object required: - internet_access properties: internet_access: type: string enum: - closed - open - restricted description: >- closed blocks external egress; open permits public internet; restricted enforces the supplied CIDR and domain controls. cidr_allowlist: type: array description: IPv4 CIDRs reachable under restricted access. items: type: string example: 203.0.113.0/24 domain_allowlist: type: array description: >- DNS names resolvable under restricted access. A bare name is exact; *.example.com includes subdomains; * permits all names. items: type: string example: '*.example.com' Error: type: object required: - error - message - code properties: error: type: string description: Stable machine-readable error code. example: invalid_request message: type: string description: Human-readable explanation. example: Invalid request body code: type: integer description: HTTP status code. example: 400 responses: BadRequest: description: Invalid request or pagination parameters. content: application/json: schema: $ref: '#/components/schemas/Error' Unauthorized: description: Missing, invalid, or expired bearer token. content: application/json: schema: $ref: '#/components/schemas/Error' Forbidden: description: Sandbox access is not enabled for the organization. content: application/json: schema: $ref: '#/components/schemas/Error' Conflict: description: Name is in use or another operation conflicts. content: application/json: schema: $ref: '#/components/schemas/Error' TooManyRequests: description: Rate limit exceeded. Honor the Retry-After header. headers: Retry-After: description: Seconds until another request should be attempted. schema: type: integer content: application/json: schema: $ref: '#/components/schemas/Error' InternalError: description: Sandbox request failed unexpectedly. content: application/json: schema: $ref: '#/components/schemas/Error' Unavailable: description: >- Capacity, access verification, control plane, or scheduler is unavailable. content: application/json: schema: $ref: '#/components/schemas/Error' GatewayTimeout: description: Scheduler did not respond in time and the sandbox was not started. content: application/json: schema: $ref: '#/components/schemas/Error' securitySchemes: bearerAuth: type: http scheme: bearer bearerFormat: API token description: API token created in the Thunder console. ````