On Mon, Aug 14, 2017 at 04:29:01AM -0700, [email protected] wrote:
TL;DR: I have developed a way to scan any template and see if there are
suspicious/incorrect code patterns in them, so the templates will remain
valid even after foreman code changes.
Recently I have started to think about user created templates and foreman
upgrades.
When user upgrades foreman, hist default templates get upgraded by the
installer/migrations, but templates created by the user (both cloned and
from scratch) are not touched.
This could lead to invalid templates and broken provisioning functionality
for the user.
Good example for this would be the change
<https://github.com/theforeman/foreman/commit/7b966530c9ba48b2a37416465a3c9619f7143387>
from calling to <%= foreman_url %> to <%= foreman_url('built') %>
I was looking for a way to inspect any template, in order to identify
problematic code as soon as the system is upgraded.
I came down to a solution based on rubocop - it's already analyzing source
files for patterns.
I have created a POC that analyzes a template written to a file, and
presents the resulting errors as regular rubocop (clang style).
All source codes are available as gist:
https://gist.github.com/ShimShtein/341b746f15826261053e97c2f435ff1a
Small explanation for the gist:
Entry point: inspect_template.rb
Usage:
Put everything from the gist to a single folder and execute:
inspect_template /path/to/template_source.erb
This script aggregates all the parts that are needed to create the
clang-like output.
The process:
1. Strip all non-ruby text from the template. This is done by
erb_strip.rb. It turns everything that is not a ruby code into spaces, so
the ruby code remains in the same places as it was in the original file.
2. Run rubocop with custom rules and erb monkey patch and produce a json
report
1. foreman_callback_cop.rb custom rule file. The most interesting
line is "def_node_matcher :foreman_url_call?, '(send nil :foreman_url)
'". Here you define which pattern to look for in the AST, in our case
we are looking for calls (send) for foreman_url method without parameters.
2. foreman_erb_monkey_patch.rb file: Patches rubocop engine to treat
*.erb files as source files and not skip them.
3. Process the resulting json to convert it to clang style highlighting.
Possible usages:
- Scanning all template after foreman upgrade to see that they are still
valid.
- Linting a template while while editing.
- Using rubocop's autocorrect feature to automatically fix offences
found by this process.
Long shot: we can create custom rules to inspect code for our plugins too,
especially if we start creating custom rules in rubocop.
I am interested in comments, opinions and usages to see how to proceed from
here.
I think this is great and it should already include deprecations so
users get a heads up something changed. Otherwise users are not aware of
it and continue writing the deprecated styles. Auto-fix is fine but
having them review it can also be a teaching tool.
Another thing to consider is automatically referring to the correct
documentation for functions.
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