Monorepo for Tangled
spindle/microvm: check for the existence of toplevel path in caches
Signed-off-by: dawn <dawn@tangled.org>
+39
-2
+39
-2
spindle/engines/microvm/engine.go
+39
-2
spindle/engines/microvm/engine.go
···
7
7
"fmt"
8
8
"io"
9
9
"log/slog"
10
+
"net/http"
10
11
"os"
11
12
"path/filepath"
12
13
"slices"
···
434
435
if record, ok, err := state.NixOSToplevelCache.Lookup(configKey); err != nil {
435
436
return err
436
437
} else if ok {
437
-
cachedToplevel = record.Toplevel
438
-
fmt.Fprintf(out, "realizing cached NixOS config %s\n", cachedToplevel)
438
+
// todo(dawn): we should probably use gc roots to eliminate TOCTOU
439
+
// the spindle will have to manage the gc roots, and for remote we have to
440
+
// ssh in to the host and add / remove gc root.
441
+
// we need to have this check anyway since the only check http caches can
442
+
// use is this one, since we cant manage gc roots there...
443
+
if e.anyCacheHasPath(ctx, state, record.Toplevel) {
444
+
cachedToplevel = record.Toplevel
445
+
fmt.Fprintf(out, "realizing cached NixOS config %s\n", cachedToplevel)
446
+
}
439
447
}
440
448
}
441
449
if cachedToplevel == "" {
···
478
486
}
479
487
fmt.Fprintf(out, "committed config cache metadata %s -> %s\n", configKey, result.Toplevel)
480
488
return nil
489
+
}
490
+
491
+
func (e *Engine) anyCacheHasPath(ctx context.Context, state *workflowState, storePath string) bool {
492
+
upstreams, err := BuildCacheUpstreams(e.cfg.NixCache.ReadURLs, state.CacheReadURLs)
493
+
if err != nil {
494
+
e.l.Warn("config cache check: build upstreams failed; treating as absent", "path", storePath, "error", err)
495
+
return false
496
+
}
497
+
if len(upstreams) == 0 {
498
+
return false
499
+
}
500
+
hash, _, err := parseStorePath(storePath)
501
+
if err != nil {
502
+
e.l.Warn("config cache check: invalid toplevel path; treating as absent", "path", storePath, "error", err)
503
+
return false
504
+
}
505
+
req, err := http.NewRequestWithContext(ctx, http.MethodHead, "http://upstream/"+hash+".narinfo", nil)
506
+
if err != nil {
507
+
e.l.Warn("config cache check: build request failed; treating as absent", "path", storePath, "error", err)
508
+
return false
509
+
}
510
+
resp, err := newNarinfoExistenceTransport(upstreams, e.l).RoundTrip(req)
511
+
if err != nil {
512
+
e.l.Warn("config cache check: narinfo probe failed; treating as absent", "path", storePath, "error", err)
513
+
return false
514
+
}
515
+
defer resp.Body.Close()
516
+
_, _ = io.Copy(io.Discard, resp.Body)
517
+
return resp.StatusCode == http.StatusOK
481
518
}
482
519
483
520
func (e *Engine) DestroyWorkflow(ctx context.Context, wid models.WorkflowId) error {