> ## Documentation Index > Fetch the complete documentation index at: https://docs.fly.io/llms.txt > Use this file to discover all available pages before exploring further. # Attach to Exec Session > Attach to an existing exec session via WebSocket. ## AsyncAPI ````yaml sprites/api/asyncapi.json execBySessionId id: execBySessionId title: Attach to Exec Session description: Attach to an existing exec session via WebSocket. servers: - id: production protocol: wss host: api.sprites.dev bindings: [] variables: [] address: /v1/sprites/{name}/exec/{session_id} parameters: - id: name jsonSchema: type: string description: Sprite name within the organization. description: Sprite name within the organization. type: string required: true deprecated: false - id: session_id jsonSchema: type: string description: Exec session identifier. description: Exec session identifier. type: string required: true deprecated: false bindings: [] operations: - &ref_1 id: execBySessionIdReceive title: 'Attach to Exec Session: messages from client' description: Messages the Sprites API receives from the client. type: receive messages: - &ref_3 id: ResizeMessage contentType: application/json payload: - name: ResizeMessage type: object properties: - name: type type: string description: resize required: true - name: cols type: integer description: New column count required: true - name: rows type: integer description: New row count required: true headers: [] jsonPayloadSchema: type: object properties: type: type: string const: resize x-parser-schema-id: cols: type: integer minimum: 0 maximum: 65535 description: New column count x-parser-schema-id: rows: type: integer minimum: 0 maximum: 65535 description: New row count x-parser-schema-id: required: - type - cols - rows examples: - cols: 180 rows: 50 type: resize x-parser-schema-id: ResizeMessage title: Resize message example: |- { "cols": 180, "rows": 50, "type": "resize" } bindings: [] extensions: - id: x-parser-unique-object-id value: ResizeMessage bindings: [] extensions: &ref_0 - id: x-parser-unique-object-id value: execBySessionId - &ref_2 id: execBySessionIdSend title: 'Attach to Exec Session: messages to client' description: Messages the Sprites API sends to the client. type: send messages: - &ref_4 id: SessionInfoMessage contentType: application/json payload: - name: SessionInfoMessage type: object properties: - name: type type: string description: session_info required: true - name: session_id type: string description: Session ID required: true - name: command type: string description: Command being executed required: true - name: created type: integer description: Unix timestamp of session creation required: true - name: cols type: integer description: Terminal columns (TTY mode only) required: true - name: rows type: integer description: Terminal rows (TTY mode only) required: true - name: is_owner type: boolean description: Whether this attachment owns the session required: true - name: tty type: boolean description: Whether session is in TTY mode required: true headers: [] jsonPayloadSchema: type: object properties: type: type: string const: session_info x-parser-schema-id: session_id: type: string description: Session ID x-parser-schema-id: command: type: string description: Command being executed x-parser-schema-id: created: type: integer format: int64 description: Unix timestamp of session creation x-parser-schema-id: cols: type: integer minimum: 0 maximum: 65535 description: Terminal columns (TTY mode only) x-parser-schema-id: rows: type: integer minimum: 0 maximum: 65535 description: Terminal rows (TTY mode only) x-parser-schema-id: is_owner: type: boolean description: Whether this attachment owns the session x-parser-schema-id: tty: type: boolean description: Whether session is in TTY mode x-parser-schema-id: required: - type - session_id - command - created - cols - rows - is_owner - tty examples: - cols: 120 command: bash created: 1767609000 is_owner: true rows: 40 session_id: '1847' tty: true type: session_info x-parser-schema-id: SessionInfoMessage title: Session info message example: |- { "cols": 120, "command": "bash", "created": 1767609000, "is_owner": true, "rows": 40, "session_id": "1847", "tty": true, "type": "session_info" } bindings: [] extensions: - id: x-parser-unique-object-id value: SessionInfoMessage - &ref_5 id: ExitMessage contentType: application/json payload: - name: ExitMessage type: object properties: - name: type type: string description: exit required: true - name: exit_code type: integer description: Process exit code required: true headers: [] jsonPayloadSchema: type: object properties: type: type: string const: exit x-parser-schema-id: exit_code: type: integer description: Process exit code x-parser-schema-id: required: - type - exit_code examples: - exit_code: 0 type: exit x-parser-schema-id: ExitMessage title: Exit message example: |- { "exit_code": 0, "type": "exit" } bindings: [] extensions: - id: x-parser-unique-object-id value: ExitMessage bindings: [] extensions: *ref_0 sendOperations: - *ref_1 receiveOperations: - *ref_2 sendMessages: - *ref_3 receiveMessages: - *ref_4 - *ref_5 extensions: - id: x-parser-unique-object-id value: execBySessionId securitySchemes: - id: bearerAuth name: bearerAuth type: http description: >- Sprites API token in the form `//`, sent as `Authorization: Bearer ` on the upgrade request. scheme: bearer extensions: [] ````