hst/instance: define instance state

This is now part of the hst API. This change also improves identifier generation and serialisation.

Signed-off-by: Ophestra <cat@gensokyo.uk>

internal/app/state/state.go

@@ -3,7 +3,6 @@ package state
 
 import (
 	"errors"
-	"time"
 
 	"hakurei.app/hst"
 )
@@ -11,8 +10,6 @@ import (
 // ErrNoConfig is returned by [Cursor] when used with a nil [hst.Config].
 var ErrNoConfig = errors.New("state does not contain config")
 
-type Entries map[ID]*State
-
 type Store interface {
 	// Do calls f exactly once and ensures store exclusivity until f returns.
 	// Returns whether f is called and any errors during the locking process.
@@ -29,21 +26,8 @@ type Store interface {
 
 // Cursor provides access to the store of an identity.
 type Cursor interface {
-	Save(state *State) error
-	Destroy(id ID) error
-	Load() (Entries, error)
+	Save(state *hst.State) error
+	Destroy(id hst.ID) error
+	Load() (map[hst.ID]*hst.State, error)
 	Len() (int, error)
 }
-
-// State is the on-disk state of a container instance.
-type State struct {
-	// Unique instance id, generated by internal/app.
-	ID ID `json:"instance"`
-	// Shim process pid. This runs as the target user.
-	PID int `json:"pid"`
-	// Configuration value used to start the container.
-	Config *hst.Config `json:"config"`
-
-	// Exact point in time that the shim process was created.
-	Time time.Time `json:"time"`
-}