> ## Documentation Index
> Fetch the complete documentation index at: https://vastai-80aa3a82-auto-openapi-update-8483c1e9.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# Update Instance SSH Key

> Updates the public key value of an existing SSH key associated with the specified instance.



## OpenAPI

````yaml /api-reference/openapi.yaml put /api/v0/instances/{id}/ssh/
openapi: 3.1.0
info:
  title: Vast.ai API
  description: >-
    Vast.ai REST API for managing GPU cloud instances, machine operations, and
    AI/ML workflows.


    ## AI Agent Quick-Start


    Install the CLI skill for your agent (Claude Code, Cursor, Windsurf, etc.):
      npx skills add vast-ai/vast-cli

    CLI reference:
    https://raw.githubusercontent.com/vast-ai/vast-cli/master/vastai/SKILL.md

    SDK reference:
    https://raw.githubusercontent.com/vast-ai/vast-cli/master/vastai_sdk/SKILL.md


    ## Auth

    All endpoints require `Authorization: Bearer $VAST_API_KEY`.

    Get your key at: https://cloud.vast.ai/manage-keys/


    ## Key Quirks

    - `gpu_ram` in CLI = GB; in REST API = MB (CLI auto-converts)

    - SSH keys must be registered BEFORE creating an instance (VM: no recovery;
    Docker: can add post-create)

    - `onstart` field is limited to 4048 characters -- gzip+base64 for longer
    scripts

    - `POST /api/v0/asks/{id}/` (create instance) returns `new_contract` as the
    instance ID, not `id`

    - Poll trap: if `actual_status` becomes `exited`, `unknown`, or `offline` it
    will never reach `running` -- destroy and retry
  version: 1.0.0
  contact:
    name: Vast.ai Support
    url: https://discord.gg/vast
servers:
  - url: https://console.vast.ai
    description: Production server
security:
  - BearerAuth: []
paths:
  /api/v0/instances/{id}/ssh/:
    put:
      tags:
        - Instances
      summary: Update Instance SSH Key
      description: >-
        Updates the public key value of an existing SSH key associated with the
        specified instance.
      parameters:
        - name: id
          in: path
          required: true
          schema:
            type: integer
          description: Instance contract ID on which to update the SSH key.
      requestBody:
        content:
          application/json:
            schema:
              type: object
              properties:
                ssh_key_id:
                  type: integer
                  description: ID of the SSH key record to update.
                  example: 42
                ssh_key:
                  type: string
                  description: New public key string to set on the SSH key record.
                  example: ssh-rsa AAAAB3NzaC1yc2E...
      responses:
        '200':
          description: >-
            Returns {success: false, error: "no_such_instance"} if the instance
            is not found or not owned by the caller, or {success: false, error:
            "add_ssh_to_instance"} on unexpected error.
          content:
            application/json:
              schema:
                type: object
                properties:
                  success:
                    type: boolean
                    description: True when updated
                  msg:
                    type: string
                    description: Human-readable status message
                  key:
                    type: string
                    description: JSON-encoded updated SSH key object
              example:
                success: true
                msg: SSH key was updated.
                key: '{}'
      security:
        - BearerAuth: []
components:
  securitySchemes:
    BearerAuth:
      type: http
      scheme: bearer
      description: API key must be provided in the Authorization header

````