I believe I've tracked the issue down to the following PR: https://github.com/canonical/cloud-init/pull/290
It looks like because we are declaring the boothook using only the content type, the content type is being overridden with x-shellscript because of the following code: https://github.com/canonical/cloud-init/blob/e1e54d2e2f9b4529276a89fa0a35e76f9964ca2a/cloudinit/user_data.py#L129-L133
I don't believe this behavior is correct since it is overriding correctly set content types with different content types (in this case overriding text/cloud-boothook with text/x-shellscript).
I believe I've tracked the issue down to the following PR: https:/ /github. com/canonical/ cloud-init/ pull/290
It looks like because we are declaring the boothook using only the content type, the content type is being overridden with x-shellscript because of the following code: https:/ /github. com/canonical/ cloud-init/ blob/e1e54d2e2f 9b4529276a89fa0 a35e76f9964ca2a /cloudinit/ user_data. py#L129- L133
I don't believe this behavior is correct since it is overriding correctly set content types with different content types (in this case overriding text/cloud-boothook with text/x- shellscript) .