awk
by awk
~1 min read

Tags

  • emacs
  • aws

After spending some time working in AWS Cloudformation and running cfn-lint manually, I decided to incorporate it into my Emacs config.

Here’s a basic cloudformation-mode for DOOM Emacs, complete with a flycheck checker for cfn-lint:

;; cloudformation-mode

(define-derived-mode cfn-mode yaml-mode
  "Cloudformation"
  "Cloudformation template mode.")

(add-to-list 'auto-mode-alist '(".template\\'" . cfn-mode))
(after! flycheck
  (flycheck-define-checker cfn-lint
    "A Cloudformation linter using cfn-python-lint.

See URL 'https://github.com/awslabs/cfn-python-lint'."
    :command ("cfn-lint" "-f" "parseable" source)
    :error-patterns (
                     (warning line-start (file-name) ":" line ":" column
                              ":" (one-or-more digit) ":" (one-or-more digit) ":"
                              (id "W" (one-or-more digit)) ":" (message) line-end)
                     (error line-start (file-name) ":" line ":" column
                            ":" (one-or-more digit) ":" (one-or-more digit) ":"
                            (id "E" (one-or-more digit)) ":" (message) line-end)
                     )
    :modes (cfn-mode)
    )
    (add-to-list 'flycheck-checkers 'cfn-lint)
  )

Of course, this only covers the YAML case, and technically JSON is valid Cloudformation as well… but who hates themselves enough to write Cloudformation in JSON?