[Solved] How "Mender Artifact" will work with the manifest (rootfs' sha256 hash)?

General Discussions
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1

Hi,

I would like to modify one file (13MB file) of the rootfs (mender artifact) after the Yocto build.
The possible easy option is to use the provided mender-artifact tool to modify the file with cp command.
The above method is clear to me however, I’m confused with the manifest file.

Whether mender-artifact tool will automatically update the manifest with the updated SHA256 hash of the “<rootfs>.ext4”?
It is not clear for me from the examples that, what happens to the manifest once, we changed any rootfs file.

2

If using yocto, can you not use the rootfs post processing hooks to edit rootfs prior to the images being made?

ROOTFS_POSTINSTALL_COMMAND

ROOTFS_POSTPROCESS_COMMAND

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3

Thank you @dellgreen for the suggestion.

Sorry for the confusion. My use case is different. The modification which I mentioned is not happening on the same build machine. It is happening on another machine where the file needs to be copied into the .mender artifact.
Hence, mender-artifact tools suits for my case.

Could you please let me know whether mender-artifact tool automatically take care of the manifest file present inside the .mender artifact?

4

I would expect the tool to update the sha256 hash if you are using mender-artifact cp

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5

Even I expect the same @mirzak.

I have tried to untar and checked the manifest before and after the update (with cp command). The rootfs sha256 hash is changing. However, I need a confirmation that our expection is correct :slight_smile:

6

I would expect the hash to change and the new artifact to be resigned if you have supplied the key.

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7

@dellgreen - Just to clarify, I have no signing in place. I’m just copy one file into the rootfs (.mender). However, the .ext4 SHA256 hash will change as per my knowledge.

8

The manifest file should be recreated with the new sha.

Same goes for resigning.

If this does not work, I would call it a bug.

@ajithpv have you tried this and it fails? Or is this research simply?

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9

@oleorhagen thank you for your confirmation.

I have tried and is working as I mentioned previously.

I need to submit this method to another team and hence I thought of asking and get confirmation from the experts :slight_smile:

Thank you @mirzak , @dellgreen and @oleorhagen for your time :+1:

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