Firecracker.Vsock (firecracker v0.1.0)

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Configures a virtio-vsock device for host-guest communication in Firecracker.

Virtio-vsock provides a high-performance, low-latency communication channel between the host and guest VM using a socket-like API. This is useful for secure, efficient data transfer and service communication.

Fields

  • :guest_cid - Required. Guest context identifier (unique ID for the VM)
  • :uds_path - Required. UNIX domain socket path on the host for vsock communication
  • :vsock_id - Optional. Identifier for the vsock device

Configuration Behavior

No fields can be modified after VM starts

Context IDs (CIDs)

  • Guest CID must be a positive integer unique to each VM
  • CID 0 and 1 are reserved for the hypervisor
  • CID 2 is reserved for the host
  • Guest CIDs typically start from 3

Notes

  • The UNIX domain socket path must be accessible to the Firecracker process
  • Vsock provides better performance than traditional network-based communication
  • Only one vsock device can be configured per VM
  • The socket path should not already exist when starting the VM
  • Vsock is ideal for agent communication, file transfer, and microservice patterns

Summary

Types

t()

Types

t()

@type t() :: %Firecracker.Vsock{
  applied?: boolean(),
  guest_cid: pos_integer(),
  uds_path: String.t(),
  vsock_id: String.t() | nil
}