externals.go RawHistoryFolder

1// SPDX-License-Identifier: MIT
2
3package sandbox
4
5import (
6	"crypto/sha256"
7	"encoding/hex"
8	"sort"
9)
10
11// External is one tool the host provides outside the image (Node.js), attached
12// read-only at GuestExternalsDir/<Name>.
13type External struct {
14	// Name is the directory below GuestExternalsDir: node20, node24,
15	// node20_alpine, node24_alpine.
16	Name string
17	// ID identifies the content: it changes whenever the files (or the reason of
18	// an unavailable tool) change, so that drivers can key caches on it.
19	ID string
20	// Dir is the host directory that is attached. For an unavailable tool it
21	// holds the file ExternalUnavailableFile with the reason, and a bin/node
22	// script that prints it and fails.
23	Dir string
24	// Unavailable is true when the tool is missing on this runner.
25	Unavailable bool
26}
27
28// ExternalsSource hands the drivers the current set of externals. It is called
29// at every sandbox start and may change between calls (a download finishing).
30type ExternalsSource interface {
31	Externals() []External
32}
33
34// ExternalsKey is the cache key of a set: the same tools give the same key, in
35// any order, and any change of content gives another.
36func ExternalsKey(set []External) string {
37	ids := make([]string, 0, len(set))
38	for _, e := range set {
39		ids = append(ids, e.Name+"="+e.ID)
40	}
41	sort.Strings(ids)
42	h := sha256.New()
43	for _, id := range ids {
44		h.Write([]byte(id))
45		h.Write([]byte{0})
46	}
47	return hex.EncodeToString(h.Sum(nil))[:16]
48}
49
50// ExternalsOf returns the current set of cfg (nil when there is none).
51func (c Config) ExternalsOf() []External {
52	if c.Externals == nil {
53		return nil
54	}
55	return c.Externals.Externals()
56}