# VersionTasks

Provides an opinionated, but rational, set of mix tools for managing
version numbers for your Elixir project using the following scheme.

```
Major.Minor.Patch
```

You decide what each version number means, whether it's [semantic
versionning](http://semver.org/), [Spec-ulation from Rich Hickey](https://www.youtube.com/watch?v=oyLBGkS5ICk), or any other scheme.

## Installation

```elixir
@deps [
  {:version_tasks, "~> 0.12.0"}
]
```

## Usage

A set of Mix Tasks for managing your version numbers.  This is best used
in conjunction with your release strategy, and so we also provide some
opionated generated code / bash scripts to support you in your quest for
towards continuous deployment.

To get a list of all available mix tasks (in case the docs might be stale),
you can run

    mix version

Below is a bit more information about the available tasks and how to use them.

### Information Tasks

The following tasks just report back information about your project
without actually changing it.

Here's the basic usage

    MIX_QUIET=1 mix version.<current|inc|next|tag|up>

Notice the MIX_QUIET=1, can sometimes be important if you are
using this within a `dev` environment where additional debugging
output might be included

The examples below will omit the `MIX_QUIET=1`for brevity, and as
it isn't strictly required.

#### mix version.current

To retrieve the current version of your application, run

    mix version.current

The call back returns the current version of your project, for example

    1.2.3

This is based on your mix.exs file.

#### mix version.next

To retrieve the _next_ version of your application, run

    mix version.next <major|minor|patch>?

The default increment step is patch, here are a few examples from the version above

    mix version.next
    1.2.4

    mix version.next patch
    1.2.4

    mix version.next minor
    1.3.0

    mix version.next major
    2.0.0

#### mix version.name

After an upgrade, you might want to trigger additional actions, such as run tests
create a release and deploy an update.  You can ask for the `name` of the version using:

    # For anything like X.0.0, that's a major release
    mix version.name
    major

    # For anything like X.Y.0, that's a minor release
    mix version.name
    minor

    # For all other releases, like X.Y.Z, that's a patch release
    mix version.name
    patch

#### mix version.is_release

This is the same as `mix version.name` with the exception that it will only return the
version name *IF* the last commit was a version commit, which looks like `vX.Y.Z`.

    # If the last commit was `Doing something great`, then it returns nothing
    mix version.is_release

    # However, if the last commit was `v1.2.0`, then it returns `minor`
    mix version.is_release
    minor

#### mix version.last_commit

To help us trigger when a release has been requested, we are exposing the last commit
message, this delegates to git and simply calls (`git log --format=%B -n 1 HEAD`)

    # Grab the last commit
    mix version.last_commit
    Simplify the database backup, to make restore easier

    # Hey, this commmit looks like a new release was commit
    mix version.last_commit
    v1.4.5


#### mix version.(major|minor|patch)

You can also expose just the major number, or minor number or patch number.
This would be useful for scriping where you wanted to join the numbers with
a dash, and your `bash` is not up to the par, so you call it out individually.

    # Let's assume `mix version.current` is 1.2.3
    mix version.major
    1

    mix version.minor
    2

    mix version.patch
    3

### Local Editing Tasks

The following tasks will edit your local files, but will not commit or push any of those changes.

#### mix version.inc

Increment your project to the next version, this will update your mix.exs AND your README.md file.

    mix version.inc <major|minor|patch>?

Your `mix.exs` MUST HAVE a variable named as follows for this to work

      @version "1.2.3"

This is the default is based on a template from [Dave Thomas](https://pragdave.me/) with his `mix gen <template>`
alternative to mix new.  [A video explaining mix gen and mix template](https://pragdave.me/blog/2017/04/18/elixir-project-generator.html?utm_content=buffera10cf&utm_medium=social&utm_source=twitter.com&utm_campaign=buffer)

And your `README.md` SHOULD HAVE an installation section as follows:

      @deps [
        {:your_app_name, "~> 0.12.0"}  # <-- that's the important line to have
      ]

### Git Interaction Tasks

These next set of tasks will commit to your local repository and/or push to your local repository.

#### mix version.up

Upgrade the version number on your project and commit the changes files to your local git repository.

    mix version.up <major|minor|patch>?

#### mix version.tag

Following the `version.up`, we can tag and push the changes to your remote branch.

    mix version.tag

This will tag your repo with `vMajor.Minor.Patch` and push the tag to your remote branch.

### mix version.untag

Undoes the effects of a mix version.tag

  mix version.untag

This will remove the tag in your repo with `vMajor.Minor.Patch` and push the delete to the remote branch as well.

### Publishing To Hex

Before you can use this task, you need to ensure you have registered with hex directly, you
can do this from the command line with

    mix hex.user register

If you already have an account, but you haven't authenticated yourself on this device,
then you can run

    mix hex.user auth

Once you have an account, and are authorized, a upgrade script can look like.
Here's a script to upgrade your package on hex

    mix do version.up <major|minor|patch>, version.tag && \
      mix test && \
      mix hex.publish

I usually drop this in a `./bin/hexup` bash script in my project,
as `mix test` needs the `MIX_ENV=test`, and you cannot combine
updating the version number with `hex.publish` as it won't pick
up the new version you just created.

### Auto publish to Hex.

You can configure an automatic push to hex, but to do that you
cannot have a passphrase associated with your key.

    mix hex.user passphrase

And then you install a git hook which will install a post-commit
hook

    mix githooks.hexup

If you want to keep your passphrase, then it will be stored in plaintext
inside your .git/hooks directory, simply call

    mix githooks.hexup <passphrase>

Your passphrase should be different then your hex.pm password.

### Custom Deploy.

You can configure an automatic deploy (as defined in a script
`./bin/deploy` using a git post-commit hook.  To install it, run

    mix githooks.deploy

This will install a `.git/hooks/post-commit` hook that when a new
version is detected will run a `./bin/deploy` script. You can specify
your own script by running

    mix githooks.deploy bin/customdeploy

If the deploy file does not exist, then we will create one for you,
but it won't do much, basically just

    mix test && \
      mix version.tag

### Release Helper Functions

#### mix version.bin.release

When creating releases (aka `mix release`), there are a few scripts that
are handy to have around to start a console, or upgrade the release, etc.
To install these scripts into your project, run

    mix version.bin.release <release_dir>?

You can provide an optional `<release_dir>` (defaults to `/src/{appname}rel`)
which knows how to grab your created release and put it in a git repo.  If
you don't know or don't care for this, then ignore it.

This will create the following files:

    ./bin/package/prerelease    # Fetch dependencies, compile, build and digest assets
    ./bin/package/release       # Generate an "upgradeable" ERTS release
    ./bin/package/retain        # Commit your release to a separate repo

    ./bin/run/rel               # run any other `release` task available
    ./bin/run/launch            # Start you app (if stopped), upgrade if running
    ./bin/run/debug             # Start you app from code in an iEX shell

It will also create two custom commands, and place them in

    ./rel/commands/clear_cache  # Clear the phoenix cache to support hot code swapping
    ./rel/commands/migrate      # Migrate your ecto database

To make these available, you will need to follow the instructions to add them
to your `rel/config.exs` file.  It will look similar to:

    release :<your appname> do

      ...

      # Add these to your :commands
      set commands: [
        "clear_cache": "rel/commands/clear_cache",
        "migrate": "rel/commands/migrate"
      ]

    end

Once available, you will be able to call them directly, such as

    ./bin/<appname> clear_cache
    ./bin/<appname> migrate

Please note that Phoenix (at present), was not reloading the re-compiled static
assets on an `upgrade`, so we also write a `&<AppModule>.ReleaseTasks.clear_cache/0` to
deal with ensuring that javascript and CSS are properly available.

    ./lib/<appname>/release_tasks.ex

You will need to commit these files to you project.  If you edit them, please let
me (aforward@gmail.com) as the changes might be relevant to others.


#### mix version.bin.ff

This will create a `&<AppModule>.FeatureFlags` GenServer, which is really just a
simple map of `enabled` or `disabled` atoms.

To install these scripts into your project, run

    mix version.bin.ff

To enable a feature flag, say `deploying`, run

    <AppModule>.FeatureFlags.enable(:deploying)

To disable that flag, run

    <AppModule>.FeatureFlags.disable(:deploying)

In your code, you can then make decisions based on those flags

    <%= if <AppModule>.FeatureFlags.enabled?(:deploying) do %>
      <p>We are deploying updates to server you better</p>
    <% end %>

We will also expose that functionality within your release.  It will create two
custom scripts

    ./rel/commands/enable <flag>    # Enable the provided feature <flag>
    ./rel/commands/disable <flag>   # Disable the provided feature <flag>

To make these available, you will need to follow the instructions to add them
to your `rel/config.exs` file.  It will look similar to:

    release :<your appname> do

      ...

      # Add these to your :commands
      set commands: [
        "enable": "rel/commands/enable",
        "disable": "rel/commands/disable"
      ]

    end


You will need to commit these files to you project.  If you edit them, please let
me (aforward@gmail.com) as the changes might be relevant to others.


#### mix version.bin.db

This will add helper scripts to `bin/db` for backing up and restoring your database.  Very opinionated, and only works for postgres.

To install these scripts into your project, run

    mix version.bin.db <backup_root> <dbname>

The default backup_root will be `<appname>backup` and your `dbname` will be
your `<appname>`.  Overwrite at your leisure.

The script will create the following files:

    ./bin/db/backup     # Backup your database
    ./bin/db/restore    # Restore your database

You will need to commit these files to you project.  If you edit them, please let
me (aforward@gmail.com) as the changes might be relevant to others.

## License

MIT License

----
Created:  2017-07-05Z