Error: conversion error: error generating ACI: archive/tar: cannot encode header

[zhsj]

While running docker2aci -debug docker://docker.elastic.co/kibana/kibana:6.1.3 it shows:

Error: conversion error: error generating ACI: archive/tar: cannot encode header: Format specifies USTAR; and USTAR cannot encode Linkname="rootfs/var/lib/yum/yumdb/a/6f8ba1fc41ecc5f60aac5b4b7aa28d2566c55481-audit-libs-2.7.6-3.el7-x86_64/from_repo"

The error comes from

docker2aci/lib/internal/internal.go

Line 632 in 365911f

if err := trw.WriteHeader(t.Header); err != nil {

t.Header.Format is USTAR here. The call to tar.WriteHeader triggers the error.

t.Header is parsed from

docker2aci/lib/internal/tarball/walk.go

Line 30 in 365911f

hdr, err := tarReader.Next()

which is also from Go std lib archive/tar.

So, I think the fault is not docker2aci. But should dokcer2aci do some tricks to work around this?

One approach is to unset the t.Header.Format, at least it works for me currently.

diff --git a/lib/internal/internal.go b/lib/internal/internal.go
index 1f811fc..d694c39 100644
--- a/lib/internal/internal.go
+++ b/lib/internal/internal.go
@@ -609,6 +609,7 @@ func writeACI(layer io.ReadSeeker, manifest schema.ImageManifest, curPwl []strin
        fileMap := make(map[string]struct{})
        var whiteouts []string
        convWalker := func(t *tarball.TarFile) error {
+               t.Header.Format = tar.FormatUnknown
                name := t.Name()
                if name == "./" {
                        return nil

Any suggestions?

[zhsj]

The previous comment is false, the error is still in appc/docker2aci

docker2aci/lib/internal/internal.go

Line 629 in 365911f

t.Header.Linkname = path.Join("rootfs", t.Linkname())

Here, the len(Linkname) > 100, making the t.Header.Format which is USTAR invalid.

[lucab]

How did you build this docker2aci binary? I'm starting to suspect that this is a regression in Go 1.10. If I try with the binary attached to the github release or with one locally built with go-1.9, I can't seem to reproduce this.

[zhsj]

@lucab tried myself, and I can confirm the binary on github release is fine. And the one built by Go 1.10 failed.

The build method is nothing special, just go build.

[lucab]

Thanks for confirming, that's also the behavior I see with a local go-1.10 build. I reported the regression to golang/go#24821, and I'd be happier if this turns out to be directly fixed in archive/tar.