Fix invalid MIME formatting in multipart cloudinit userdata

[devinlundberg]

Per https://tools.ietf.org/html/rfc822#appendix-B.2, MIME headers and Body need to be separated by two new lines (or CRLFs in this case).

The email parser in python can handle this which is what cloud-init uses but this bug causes problems if you try to parse the multipart message by languages other than python.

[radeksimko]

Hi @devinlundberg
thanks for the contribution, I agree this change makes sense. Just a few points before we can merge this:

1. One test is now failing, I think it'll need fixing:

=== RUN   TestRender
--- FAIL: TestRender (0.04s)
	testing.go:280: Step 0 error: Check failed: Check 1/1 error: data.template_cloudinit_config.foo: Attribute 'rendered' expected "Content-Type: multipart/mixed; boundary=\"MIMEBOUNDARY\"\nMIME-Version: 1.0\r\n--MIMEBOUNDARY\r\nContent-Transfer-Encoding: 7bit\r\nContent-Type: text/x-shellscript\r\nMime-Version: 1.0\r\n\r\nbaz\r\n--MIMEBOUNDARY--\r\n", got "Content-Type: multipart/mixed; boundary=\"MIMEBOUNDARY\"\nMIME-Version: 1.0\r\n\r\n--MIMEBOUNDARY\r\nContent-Transfer-Encoding: 7bit\r\nContent-Type: text/x-shellscript\r\nMime-Version: 1.0\r\n\r\nbaz\r\n--MIMEBOUNDARY--\r\n"
	testing.go:280: Step 0 error: Check failed: Check 1/1 error: data.template_cloudinit_config.foo: Attribute 'rendered' expected "Content-Type: multipart/mixed; boundary=\"MIMEBOUNDARY\"\nMIME-Version: 1.0\r\n--MIMEBOUNDARY\r\nContent-Disposition: attachment; filename=\"foobar.sh\"\r\nContent-Transfer-Encoding: 7bit\r\nContent-Type: text/x-shellscript\r\nMime-Version: 1.0\r\n\r\nbaz\r\n--MIMEBOUNDARY--\r\n", got "Content-Type: multipart/mixed; boundary=\"MIMEBOUNDARY\"\nMIME-Version: 1.0\r\n\r\n--MIMEBOUNDARY\r\nContent-Disposition: attachment; filename=\"foobar.sh\"\r\nContent-Transfer-Encoding: 7bit\r\nContent-Type: text/x-shellscript\r\nMime-Version: 1.0\r\n\r\nbaz\r\n--MIMEBOUNDARY--\r\n"
	testing.go:280: Step 0 error: Check failed: Check 1/1 error: data.template_cloudinit_config.foo: Attribute 'rendered' expected "Content-Type: multipart/mixed; boundary=\"MIMEBOUNDARY\"\nMIME-Version: 1.0\r\n--MIMEBOUNDARY\r\nContent-Transfer-Encoding: 7bit\r\nContent-Type: text/x-shellscript\r\nMime-Version: 1.0\r\n\r\nbaz\r\n--MIMEBOUNDARY\r\nContent-Transfer-Encoding: 7bit\r\nContent-Type: text/x-shellscript\r\nMime-Version: 1.0\r\n\r\nffbaz\r\n--MIMEBOUNDARY--\r\n", got "Content-Type: multipart/mixed; boundary=\"MIMEBOUNDARY\"\nMIME-Version: 1.0\r\n\r\n--MIMEBOUNDARY\r\nContent-Transfer-Encoding: 7bit\r\nContent-Type: text/x-shellscript\r\nMime-Version: 1.0\r\n\r\nbaz\r\n--MIMEBOUNDARY\r\nContent-Transfer-Encoding: 7bit\r\nContent-Type: text/x-shellscript\r\nMime-Version: 1.0\r\n\r\nffbaz\r\n--MIMEBOUNDARY--\r\n"

2. I'm marking it as BC. Although the change itself might not be breaking I think many users may be using this in combination with resource like aws_launch_configuration which is by design immutable and any change will therefore cause recreation, so we'll need to mark it as such in the Changelog after merging this.

[radeksimko]

👍 Thanks, tests are now passing.

[ghost]

I'm going to lock this issue because it has been closed for 30 days ⏳. This helps our maintainers find and focus on the active issues.

If you have found a problem that seems similar to this, please open a new issue and complete the issue template so we can capture all the details necessary to investigate further.