albatross
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A tree data structure including policies and dynamic usage.

Considering delegation of resources to someone, and further delegation to others - using a process which is not controlled by the authority - requires runtime tracking of these delegations and the actual usage:

If Alice may create 2 virtual machines, and she delegates the same capability further to both Bob and Charlie, the authority must still enforce that Alice, Bob, and Charlie are able to run 2 virtual machines in total, rather than 2 each.

type t = private {
  1. policies : Vmm_core.Policy.t Vmm_trie.t;
  2. block_devices : (int * bool) Vmm_trie.t;
  3. unikernels : Vmm_core.Unikernel.t Vmm_trie.t;
}

The type of the resource tree.

val empty : t

empty is the empty tree.

val find_vm : t -> Vmm_core.Name.t -> Vmm_core.Unikernel.t option

find_vm t id is either Some vm or None.

val find_policy : t -> Vmm_core.Name.t -> Vmm_core.Policy.t option

find_policy t Name.t is either Some policy or None.

val find_block : t -> Vmm_core.Name.t -> (int * bool) option

find_block t Name.t is either Some (size, active) or None.

val check_vm : t -> Vmm_core.Name.t -> Vmm_core.Unikernel.config -> (unit, [> `Msg of string ]) result

check_vm t Name.t vm checks whether vm under Name.t in t would be allowed under the current policies.

val insert_vm : t -> Vmm_core.Name.t -> Vmm_core.Unikernel.t -> t

insert_vm t Name.t vm inserts vm under Name.t in t, and returns the new t. The caller has to ensure (using check_vm) that a VM with the same name does not yet exist, and the block device is not in use.

  • raises Invalid_argument

    if block device is already in use, or VM already exists.

val insert_policy : t -> Vmm_core.Name.t -> Vmm_core.Policy.t -> (t, [> `Msg of string ]) result

insert_policy t Name.t policy inserts policy under Name.t in t, and returns the new t or an error.

val check_block : t -> Vmm_core.Name.t -> int -> (unit, [> `Msg of string ]) result

check_block t Name.t size checks whether size under Name.t in t would be allowed under the current policies.

val insert_block : t -> Vmm_core.Name.t -> int -> (t, [> `Msg of string ]) result

insert_block t Name.t size inserts size under Name.t in t, and returns the new t or an error.

val remove_vm : t -> Vmm_core.Name.t -> (t, [> `Msg of string ]) result

remove_vm t Name.t removes vm Name.t from t.

val remove_policy : t -> Vmm_core.Name.t -> (t, [> `Msg of string ]) result

remove_policy t Name.t removes policy Name.t from t.

val remove_block : t -> Vmm_core.Name.t -> (t, [> `Msg of string ]) result

remove_block t Name.t removes block Name.t from t.

val pp : t Fmt.t

pp is a pretty printer for t.