elvis

Command-line interface for Elvis, the Erlang style reviewer.

Contact Us

For questions or general comments regarding the use of this library, please use our public hipchat room.

If you find any bugs or have a problem while using this library, please open an issue in this repo (or a pull request :)).

And you can check all of our open-source projects at inaka.github.io.

Installation

1. Clone the repo
2. rebar3 compile

Usage

In any elvis-enabled product, elvis rock will trigger a rule check.

Script

elvis can be turned into a script by executing rebar3 escriptize. This will generate an elvis self-contained executable script, from which you can get help by typing elvis help. A list of available commands can be shown using the --commands option (i.e. elvis --commands).

To run elvis from the terminal use the rock command (i.e. elvis rock). There's no need to specify a configuration file path if you have an elvis.config file in the same location where you are executing the script, otherwise a configuration file can be specified through the use of the --config (or just -c) option.

elvis rock --config config/elvis.config

Webhook

There's also a way to use elvis as a GitHub webhook for pull request (PR) events by calling the webhook/1 function. This will add a comment in each file and rule that is broken, analyzing only the files associated with the PR.

elvis.inakalabs.com

This Website is available for you to add elvis as a webhook in your GitHub's repositories. Just log in with your GitHub credentials and the site will pull all the repos for which you have permissions to add webhooks. The elvis webhook can always be deactivated at any time using the same mechanism.

When activating the webhook, the site will use the GitHub API to add the user elvisinaka as a collaborator to your repo, so that it can create comments on its pull requests. If the repo belongs to an organization, a Services team is created instead (if it doesn't exist already), then this team is added to the repo and the elvisinaka user is added to that team.

When there's no elvis.config in the pull request's branch of your repo a default set of rules are run. The list of all the rules that are part of this set can be found here.

Running the webhook on your servers

Since GitHub's API needs a valid user and password to allow the creation of comments on PRs, the parameters github_user and github_password need to be added to elvis's configuration.

The webhook/1 function takes a map containing the keys headers and body, whose values should be the map of headers and the body from the GitHub's event request.

Headers = #{<<"X-GitHub-Event">>, <<"pull_request">>},
Body = <<"{}">>, %% JSON data form GitHub's event.
Request = #{headers => Headers, body => Body},
elvis:webhook(Request).

Git hook

elvis can also be used as a git pre-commit hook using the git-hook command, just use something like the following as your pre-commit script:

#!/bin/sh
#
# Runs elvis rules to staged files where applicable.

elvis git-hook

As the comment states, elvis will search for files that match the filter of each rule group (see configuration) among the staged files, get their staged content and run the rules specified in the configuration. If any rule fails then elvis exits with a non-zero code, which signals git that the commit shouldn't be made.

Make sure your pre-commit hook script is executable (i.e. by running chmod +x pre-commit), otherwise git won't be able to run it.

Erlang Shell

If you only need to use elvis in the Erlang shell you might want to consider only including the elvis_core library as a dependency.

Configuration

To provide a default configuration for elvis you should either create an elvis.config file located in the root directory or set the following environment values in your configuration file:

[
 {
   elvis,
   [
    {config, [...]},
    {output_format, plain},

    %% Only necessary for the 'webhook' functionality
    {github_user, "user"},
    {github_password, "password"}
   ]
 }
].

The config and output_format are explained in elvis_core.

The GitHub configuration parameters github_user and github_password are required only when elvis is used as a webhook.

Implemented Rules

A reference of all rules implemented in Elvis can be found in this wiki page: Rules.

User Defined Rules

If you have implemented an Elvis rule that's in your local repo or in one of your dependencies, you can add this rule to your elvis.config file and tell Elvis where to find the .beam that contains the compiled rule using the --code-path (-p) option.

For example if the rule is in one of your deps, you could run Elvis in the following way:

elvis rock -p deps/elvis_rules/ebin -c elvis.config

Dependencies

• Erlang/OTP 18+
• git

References

Inspired on HoundCI