`DockerResponseServerError { status_code: 400, message: "file with no instructions" }`

[Ferdia McKeogh]

The following function for creating a WASM image in the local registry works in bollard 0.14.0 but fails with DockerResponseServerError { status_code: 400, message: "file with no instructions" } in bollard 0.15.0.

I have bisected the commits, and it appears that it was merge request #335 that caused the issue, but I can't find out how sending an empty changes field causes the error.

/// Creates an image in the local registry from the provided WASM module bytes
pub async fn create_image_from_slice(
    image_name: &str,
    tag: &str,
    module: &[u8],
) -> eyre::Result<()> {
    let options = CreateImageOptions {
        from_src: "-",    // from_src must be "-" when sending the archive in the request body
        repo: image_name, // The name of the image in the docker daemon.
        tag,              // The tag of this particular image.
        ..Default::default()
    };

    // Create a Body from the byte slice
    let req_body = hyper::body::Body::from({
        let mut buffer = Vec::new();

        {
            let mut builder = tar::Builder::new(&mut buffer);
            let mut header = tar::Header::new_gnu();
            header.set_path("entrypoint.wasm")?;
            header.set_size(module.len() as u64);
            header.set_cksum();

            builder.append_data(&mut header, "entrypoint.wasm", module)?;
            builder.finish()?;
        }

        buffer
    });

    // Call Docker::create_image with the options and the body
    Docker::connect_with_local_defaults()?
        .create_image(Some(options), Some(req_body), None)
        .collect::<Vec<_>>()
        .await
        .into_iter()
        .collect::<Result<Vec<_>, bollard::errors::Error>>()
        .unwrap();

    Ok(())
}

[Niel Drummond]

Thanks for this, I don't think we have this use case covered in our tests.. I've only recently read that this is possible.

[Ferdia McKeogh]

@fussybeaver Any recommendations on how I could debug/fix this?:)

[Niel Drummond]

I would setup an env_logger at the start of your script and run with RUST_LOG=bollard=debug to check what the request envelope looks like. You can try and compare it with a simple curl request on the docker socket to check if that's working.

[Ferdia McKeogh]

@fussybeaver Diffing the logs showed the only change was the extra &changes= parameter in the request. I think the Docker error is suggesting that if the Vec is empty the parameter shouldn't be passed? I can open a PR if that fix is acceptable to you.