Archive/tar: invalid tar header message when export or import

[swieczkowski]

Expected behavior

Success import image.

Actual behavior

"Error response from daemon: Error processing tar file(exit status 1): archive/tar: invalid tar header"

Information

• If we want to export container using > then we got wrong file/error on import.
• If we want to import image using | then we got error
• Diagnostic ID: 65607FD9-95F8-4697-86E9-82CAC340FD2A/2017-04-20_21-49-26
• Windows 10 Pro
• Docker 17.05.0-ce-rc1-wind8 (11189) edge 73d01bb
• Temporary solution for export is to use: docker export --output="export.tar" container_id
• Temporary solution for import is to use: docker import export.tar

Steps to reproduce the behavior

1. docker export container_id > export.tar
2. cat export.tar | docker import - exampleimagelocal:new

[snorrk]

This could be related to a PowerShell limitation: #758

[mikebolland]

Is this related to moby/moby#33586 ?

[danter]

I made some tests on my machine with the different ouput types (STDOUT or file output switch -o) and the sizes differs quite a bit and when I opened the files in a diff-tool it complains about different carriage return types.

Moving on I also opened the two files in a hex editor, and turns out the version that was created using STDOUT had a hex 0x00 character for every second character. My guess is that it might be the classical problem where carriage return differs between linux and windows, and also a problem where windows uses UTF-16 by default and not UTF-8. Effectively corrupting any form of character strings or binary data.

My system is a windows 10 pro system and I also used powershell for generating the files. Might be good to mention that when I saved the file using the file output switch -o, i managed to import the file again, but when using STDOUT, the import yielded the exact same error.

Steps to reproduce:
1 open powershell
2. docker pull alpine
3. docker save alpine > alpine.tar
4. docker rmi alpine
5. docker load -i alpine.tar (Error processing tar file(exit status 1): archive/tar: invalid tar header)

The same procedure will work if doing it from a normal command window (cmd) so most likely a pure powershell problem. However using the file output switch (-o) when saving and not STDOUT will work from powershell so it's probably best to avoid using any form of output streams when working in powershell.

[alpmarangoz]

Also files created with powershell are considerably larger. For example:

• Valid Cassandra image file created with CMD: 323,032KB
• Faulty Cassandra image created with Powershell: 653,040KB

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[andygarfield]

Use command prompt for loading the image instead. Powershell uses UTF-16 for everything, so that explains the doubling of the size.

[victorbwilson]

To export:
docker container export <container_id> -o <image_name>.tar
To import
docker image import <image_name>.tar <custom_image_name>

Please note in Windows use -o instead of >. The export done with > works with Linux/MAC only.

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