build: enhance error message for unsupported attestations

Signed-off-by: CrazyMax <[email protected]>

build/build.go

@@ -252,17 +252,22 @@ func toSolveOpt(ctx context.Context, node builder.Node, multiDriver bool, opt Op
  attests[k] = *v
  }
  }
- supportsAttestations := bopts.LLBCaps.Contains(apicaps.CapID("exporter.image.attestations")) && nodeDriver.Features(ctx)[driver.MultiPlatform]
+
+ supportAttestations := bopts.LLBCaps.Contains(apicaps.CapID("exporter.image.attestations")) && nodeDriver.Features(ctx)[driver.MultiPlatform]
  if len(attests) > 0 {
- if !supportsAttestations {
- return nil, nil, errors.Errorf("attestations are not supported by the current BuildKit daemon")
+ if !supportAttestations {
+ if !nodeDriver.Features(ctx)[driver.MultiPlatform] {
+ return nil, nil, errors.Errorf(`Attestations are not supported for the %s driver.
+Switch to a different driver, or turn on the containerd image store, and try again.`, nodeDriver.Factory().Name())
+ }
+ return nil, nil, errors.Errorf("Attestations are not supported by the current BuildKit daemon")
  }
  for k, v := range attests {
  so.FrontendAttrs["attest:"+k] = v
  }
  }
 
- if _, ok := opt.Attests["provenance"]; !ok && supportsAttestations {
+ if _, ok := opt.Attests["provenance"]; !ok && supportAttestations {
  const noAttestEnv = "BUILDX_NO_DEFAULT_ATTESTATIONS"
  var noProv bool
  if v, ok := os.LookupEnv(noAttestEnv); ok {