:toc: macro
:toclevels: 5
:figure-caption!:

:containable_link: link:https://alchemists.io/projects/containable[Containable]
:infusible_link: link:https://alchemists.io/projects/infusible[Infusible]
:ruby_gems_link: link:https://rubygems.org[RubyGems]
:sod_link: link:https://alchemists.io/projects/sod[Sod]

= Gemsmith

Gemsmith is a command line interface for smithing Ruby gems. Perfect for when you need a professional and robust tool beyond link:https://bundler.io[Bundler]'s basic gem skeletons. While Bundler is great for creating your first gem, you'll quickly outgrow Bundler when creating and maintaining multiple gems. This is where Gemsmith can increase your productivity by providing much of the tooling you need from the start with the ability to customize as desired.

toc::[]

== Features

* Supports all link:https://alchemists.io/projects/rubysmith[Rubysmith] features.
* Supports basic gem or more advanced {sod_link}-based Command Line Interface (CLI) skeletons.
* Supports gem building, installing for local development, and publishing.
* Supports the editing and viewing of installed gems.

== Requirements

. A UNIX-based system.
. link:https://www.ruby-lang.org[Ruby].
. {ruby_gems_link}.

== Setup

To install _with_ security, run:

[source,bash]
----
# 💡 Skip this line if you already have the public certificate installed.
gem cert --add <(curl --compressed --location https://alchemists.io/gems.pem)
gem install gemsmith --trust-policy HighSecurity
----

To install _without_ security, run:

[source,bash]
----
gem install gemsmith
----

== Usage

=== Command Line Interface (CLI)

From the command line, type: `gemsmith --help`

image:https://alchemists.io/images/projects/gemsmith/screenshots/usage.png[Usage,width=729,height=462,role=focal_point]

==== Build

The core functionality of this gem centers around the `build` command and associated flags. The build options allow you to further customize the kind of gem you want to build. Most build options
are enabled by default. For detailed documentation on all supported flags, see the link:https://alchemists.io/projects/rubysmith/#_build[Rubysmith] documentation.

The build option which is unique to Gemsmith is the `--cli` option. This allows you to build a gem which has a Command Line Interface (CLI). There are multiple ways a CLI can be built in Ruby but Gemsmith takes an approach which builds upon Ruby's native `OptionParser` with help from the {containable_link} and {infusible_link} gems. All of this culminates in a design that is mix of Objected Oriented + Functional Programming design. Building a gem with CLI support is a simple as running:

[source,bash]
----
gemsmith build --name demo --cli
----

The above will give you a new gem with CLI support which includes working specs. It's the same design used to build this Gemsmith gem. You'll have both a `configuration` and `CLI` namespace for configuring your gem and adding additional CLI support. Out of the box, the CLI gem generated for you supports the following options:

....
  -v, --version     Show version.
  -h, --help        Show this message.
  config            Manage configuration.
....

From here you can add whatever you wish to make an awesome CLI gem for others to enjoy.

==== Install

After you've designed, implemented, and built your gem, you'll want to test it out within your local
environment by installing it. You can do this by running:

[source,bash]
----
# Implicit
gemsmith --install

# Explicit
gemsmith --install demo
----

Gemsmith can be used to install any gem, in fact. Doesn't matter if the gem was built by Gemsmith,
Bundler, or some other tool. As long as your gem has a `*.gemspec` file, Gemsmith will be able to
install it.

==== Publish

Once you've built your gem; installed it locally; and thoroughly tested it, you'll want to publish
your gem so anyone in the world can make use of it. You can do this by running the following:

[source,bash]
----
# Implicit
gemsmith --publish

# Explicit
gemsmith --publish demo
----

Security is important which requires a GPG key for signing your Git tags and
link:https://alchemists.io/articles/ruby_gems_multi_factor_authentication/[RubyGems Multi-Factor
Authentication] for publishing to RubyGems. Both of which are enabled by default. You'll want to
read through the linked article which delves into how Gemsmith automatically makes use of your
YubiKey to authenticate with RubyGems. Spending the time to set this up will allow Gemsmith to use
of your YubiKey for effortless and secure publishing of new versions of your gems so I highly
recommend doing this.

As with installing a gem, Gemsmith can be used to publish existing gems which were not built by
Gemsmith too. As long as your gem has a `*.gemspec` file with a valid version, Gemsmith will be able
to publish it.

==== Edit

Gemsmith can be used to edit existing gems on your local system. You can do this by running:

[source,bash]
----
gemsmith --edit <name of gem>
----

If multiple versions of the same gem are detected, you'll be prompted to pick which gem you want to
edit. Otherwise, the gem will immediately be opened within your default editor (or whatever you
have set in your `EDITOR` environment variable).

Editing a local gem is a great way to learn from others or quickly debug issues.

==== View

Gemsmith can be used to view existing gem documentation. You can do this by running:

[source,bash]
----
gemsmith --view <name of gem>
----

If multiple versions of the same gem are detected, you'll be prompted to pick which gem you want to
view. Otherwise, the gem will immediately be opened within your default browser.

Viewing a gem is a great way to learn more about the gem and documentation in general.

=== Configuration

This gem can be configured via a global configuration:

....
$HOME/.config/gemsmith/configuration.yml
....

It can also be configured via link:https://alchemists.io/projects/xdg[XDG] environment
variables.

The default configuration is everything provided in the
link:https://alchemists.io/projects/rubysmith/#_configuration[Rubysmith] with the addition of
the following:

[source,yaml]
----
build:
  cli: false
----

It is recommended that you provide URLs for your project which would be all keys found in this
section:

[source,yaml]
----
project:
  uri:
    # Add sub-key values here.
----

When these values exist, you'll benefit from having this information added to your generated
`gemspec` and project documentation. Otherwise -- if these values are empty -- they are removed from
new gem generation.

=== Workflows

When building/testing your gem locally, a typical workflow is:

[source,bash]
----
# Build
gemsmith build --name demo

# Design, Implement and Test.
cd demo
bundle exec rake

# Install
gemsmith --install

# Publish
gemsmith --publish
----

=== Security

==== Git Signing Key

To securely sign your Git tags, install and configure link:https://www.gnupg.org[GPG]:

[source,bash]
----
brew install gpg
gpg --gen-key
----

When creating your GPG key, choose these settings:

* Key kind: RSA and RSA (default)
* Key size: 4096
* Key validity: 0
* Real Name: `<your name>`
* Email: `<your email>`
* Passphrase: `<your passphrase>`

To obtain your key, run the following and take the part after the forward slash:

[source,bash]
----
gpg --list-keys | grep pub
----

Add your key to your global Git configuration in the `[user]` section. Example:

....
[user]
  signingkey = <your GPG key>
....

Now, when publishing your gems with Gemsmith (i.e. `bundle exec rake publish`), signing of your Git
tag will happen automatically.

==== Gem Certificates

To create a certificate for your gems, run the following:

[source,bash]
----
cd ~/.gem
gem cert build you@example.com --days 730
gem cert --add gem-public_cert.pem
cp gem-public_cert.pem <path/to/server/public/folder>/gems.pem
----

The above breaks down as follows:

* *Source*: The `~/.gem` directory is where your credentials and certificates are stored. This is also where the `Gem.default_key_path` and `Gem.default_cert_path` methods look for your certificates. I'll talk more about these shortly.
* *Build*: Builds your `gem-private_key.pem` and `gem-public_cert.pem` certificates with a two year duration (i.e. `365 * 2`) before expiring. You can also see this information on the {ruby_gems_link} page for your gem (scroll to the bottom). Security-wise, this isn't great but the way {ruby_gems_link} certification is implemented and enforced is weak to begin with. Regardless, this is important to do in order to be a good citizen within the ecosystem. You'll also be prompted for a private key passphrase so make sure it is long and complicated and then store it in your favorite password manager.
* *Add*: Once your public certificate has been built, you'll need to add it to your registry so {ruby_gems_link} can look up and verify your certificate upon gem install.
* *Web*: You'll need to copy your public certificate to the public folder of your web server so you can host this certificate for others to install. I rename my public certificate as `gems.pem` to keep the URL simple but you can name it how you like and document usage for others. For example, here's how you'd add my public certificate (same as done locally but via a URL this time): `gem cert --add <(curl --compressed --location https://alchemists.io/gems.pem)`.

Earlier, I mentioned `Gem.default_key_path` and `Gem.default_cert_path` are paths to where your certificates are stored in your `~/.gem` directory. Well, the `signing_key` and `cert_chain` of your `.gemspec` needs to use these paths. Gemsmith automates for you when the `--security` build option is used (enabled by default). For example, when using Gemsmith to build a new gem, you'll see the following configuration generated in your `.gemspec`:

[source,ruby]
----
# frozen_string_literal: true

Gem::Specification.new do |spec|
  # Truncated for brevity.
  spec.signing_key = Gem.default_key_path
  spec.cert_chain = [Gem.default_cert_path]
end
----

The above wires all of this functionality together so you can easily build and publish your gems with minimal effort while increasing your security. 🎉 To test the security of your newly minted gem, you can install it with the `--trust-policy` set to high security for maximum benefit. Example:

[source,bash]
----
gem install <your_gem> --trust-policy HighSecurity
----

To learn more about gem certificates, check out the RubyGems
link:https://guides.rubygems.org/security[Security] documentation.

=== Private Gem Servers

By default, the following command will publicly publish your gem to {ruby_gems_link}:

[source,bash]
----
gemsmith --publish
----

You can change this behavior by adding metadata to your gemspec that will allow Gemsmith to publish
your gem to an alternate/private gem server instead. This can be done by updating your gem
specification and RubyGems credentials.

==== Gem Specification Metadata

Add the following gemspec metadata to privately publish new versions of your gem:

[source,ruby]
----
Gem::Specification.new do |spec|
  spec.metadata = {"allowed_push_host" => "https://private.example.com"}
end
----

💡 The gemspec metadata (i.e. keys and values) _must_ be strings per the
link:https://guides.rubygems.org/specification-reference/#metadata[RubyGems Specification].

Use of the `allowed_push_host` key provides two important capabilities:

* Prevents you from accidentally publishing your private gem to the public RubyGems server (default
  behavior).
* Defines the lookup key in your `$HOME/.gem/credentials` file which contains your private
  credentials for authentication to your private server (more on this below).

==== Gem Credentials

With your gem specification metadata established, you are ready to publish your gem to a public or
private server. If this is your first time publishing a gem and no gem credentials have been
configured, you'll be prompted for them. Gem credentials are stored in the RubyGems
`$HOME/.gem/credentials` file. From this point forward, future gem publishing will use your stored
credentials instead.

Multiple credentials can be stored in the `$HOME/.gem/credentials` file as well. Example:

[source,yaml]
----
:rubygems_api_key: 2a0b460650e67d9b85a60e183defa376
https://private.example.com: Basic dXNlcjpwYXNzd29yZA==
----

Notice how the first line contains credentials for the public RubyGems server while the second line
is for our private example server. You'll also notice that the key is not a symbol but a URL string
to our private server. This is important because this is how we link our gem specification metadata
to our private credentials. To illustrate further, here are both files truncated and shown together:

....
# Gem Specification: The metadata which defines the private host to publish to.
spec.metadata = {"allowed_push_host" => "https://private.example.com"}

# Gem Credentials: The URL value -- shown above -- which becomes the key for enabling authentication.
https://private.example.com: Basic dXNlcjpwYXNzd29yZA==
....

When the above are linked together, you enable Gemsmith to publish your gem using only the following
command:

[source,bash]
----
gemsmith --publish
----

This is especially powerful when publishing to
link:https://docs.github.com/en/packages/working-with-a-github-packages-registry/working-with-the-rubygems-registry[GitHub
Packages] which would look like this when properly configured (truncated for brevity while using
fake data):

....
# Gem specification
spec.metadata = {"allowed_push_host" => "https://rubygems.pkg.github.com/alchemists"}

# Gem credentials
https://rubygems.pkg.github.com/alchemists: Bearer ghp_c5b8d394abefebbf45c7b27b379c74978923
....

Lastly, should you need to delete a credential (due to a bad login/password for example), you can
open the `$HOME/.gem/credentials` in your default editor and remove the line(s) you don't need. Upon
next publish of your gem, you'll be prompted for the missing credentials.

==== Bundler Configuration

So far, I've shown how to privately _publish_ a gem but now we need to teach Bundler how to install
the gem as dependency within your upstream project. For demonstration purposes, I'm going to assume
you are using GitHub Packages as your private gem server. You should be able to quickly translate
this documentation if using an alternate private gem server, though.

The first step is to create your own GitHub Personal Access Token (PAT) which is fast to do by
following GitHub's own
link:https://docs.github.com/en/authentication/keeping-your-account-and-data-secure/creating-a-personal-access-token[documentation].
At a minimum, you'll need to enable _repo_ and _packages_ scopes with read/write access.

With your PAT in hand, you'll need to ensure link:https://bundler.io[Bundler] can authenticate to
the private GitHub Packages gem server by running the following:

[source,bash]
----
bundle config set --global rubygems.pkg.github.com <your GitHub handle>:<PAT>
# Example: bundle config set --global rubygems.pkg.github.com jdoe:ghp_c5b8d394abefebbf45c7b27b379c74978923
----

💡 Using Bundler's `--global` flag ensures you only have to define these credentials once for _all_
projects which reduces maintenance burden on you. The path to this global configuration can be found
here: `$HOME/.config/bundler/configuration.yml`.

Lastly, you can add this gem to your `Gemfile` as follows:

[source,ruby]
----
source "https://rubygems.pkg.github.com/alchemists" do
  gem "demo", "~> 0.0"
end
----

At this point -- if you run `bundle install` -- you should see the following in your console:

....
Fetching gem metadata from https://rubygems.pkg.github.com/alchemists/...
Resolving dependencies...Fetching gem metadata from https://rubygems.org/.....
....

If so, you're all set!

==== GitHub Actions/Packages Automation

Earlier, I hinted at using GitHub Packages but what if you could automate the entire publishing
process? Well, good news, you can by using GitHub Actions to publish your packages. Here's the YAML
necessary to accomplish this endeavor:

``` yaml
name: Gemsmith

on:
  push:
    branches: main

jobs:
  build:
    runs-on: ubuntu-latest
    container:
      image: ruby:latest
    permissions:
      contents: write
      packages: write

    steps:
      - name: Checkout
        uses: actions/checkout@v4
        with:
          fetch-depth: '0'
          ref: ${{github.head_ref}}
      - name: Setup
        run: |
          git config user.email "engineering@example.com"
          git config user.name "Gemsmith Publisher"
          mkdir -p $HOME/.gem
          printf "%s\n" "https://rubygems.pkg.github.com/example: Bearer ${{secrets.GITHUB_TOKEN}}" > $HOME/.gem/credentials
          chmod 0600 $HOME/.gem/credentials
      - name: Install
        run: gem install gemsmith
      - name: Publish
        run: |
          if git describe --tags --abbrev=0 > /dev/null 2>&1; then
            gemsmith --publish
          else
            printf "%s\n" "First gem version must be manually created. Skipping."
          fi
```

The above will ensure the following:

* Only the first version requires manual publishing (hence the check for existing Git tags).
* Duplicate versions are always skipped.
* Only when a new version is detected (by changing your gemspec version) and you are on the `main`
  branch will a new version be automatically published.

This entire workflow is explained in my
link:https://alchemists.io/talks/ruby_git_hub_packages[talk] on this exact subject too.

== Development

To contribute, run:

[source,bash]
----
git clone https://github.com/bkuhlmann/gemsmith
cd gemsmith
bin/setup
----

You can also use the IRB console for direct access to all objects:

[source,bash]
----
bin/console
----

== Tests

To test, run:

[source,bash]
----
bin/rake
----

== link:https://alchemists.io/policies/license[License]

== link:https://alchemists.io/policies/security[Security]

== link:https://alchemists.io/policies/code_of_conduct[Code of Conduct]

== link:https://alchemists.io/policies/contributions[Contributions]

== link:https://alchemists.io/policies/developer_certificate_of_origin[Developer Certificate of Origin]

== link:https://alchemists.io/projects/gemsmith/versions[Versions]

== link:https://alchemists.io/community[Community]

== Credits

Engineered by link:https://alchemists.io/team/brooke_kuhlmann[Brooke Kuhlmann].
