# Contributing to Qemu Plugin

**First:** if you're unsure or afraid of _anything_, just ask or submit the
issue or pull request anyway. You won't be yelled at for giving your best
effort. The worst that can happen is that you'll be politely asked to change
something. We appreciate any sort of contributions, and don't want a wall of
rules to get in the way of that.

However, for those individuals who want a bit more guidance on the best way to
contribute to the project, read on. This document will cover what we're looking
for. By addressing all the points we're looking for, it raises the chances we
can quickly merge or address your contributions.

When contributing in any way to the Packer project (new issue, PR, etc), please
be aware that our team identifies with many gender pronouns. Please remember to
use nonbinary pronouns (they/them) and gender neutral language ("Hello folks")
when addressing our team. For more reading on our code of conduct, please see the
[HashiCorp community guidelines](https://www.hashicorp.com/community-guidelines).

## Issues

### Reporting an Issue

- Make sure you test against the latest released version. It is possible we
  already fixed the bug you're experiencing.

- Run packer with debug output with the environment variable `PACKER_LOG`.
  For example: `PACKER_LOG=1 packer build template.pkr.hcl`. Take the _entire_
  output and create a [gist](https://gist.github.com) for linking to in your
  issue. Packer should strip sensitive keys from the output, but take a look
  through just in case.

- Provide a reproducible test case. If a contributor can't reproduce an issue,
  then it dramatically lowers the chances it'll get fixed. And in some cases,
  the issue will eventually be closed.

- Respond promptly to any questions made by the Packer team to your issue. Stale
  issues will be closed.

### Issue Lifecycle

1. The issue is reported.

2. The issue is verified and categorized by a Packer collaborator.
   Categorization is done via tags. For example, bugs are marked as "bugs" and
   simple fixes are marked as "good first issue".

3. Unless it is critical, the issue is left for a period of time (sometimes many
   weeks), giving outside contributors a chance to address the issue.

4. The issue is addressed in a pull request or commit. The issue will be
   referenced in the commit message so that the code that fixes it is clearly
   linked.

5. Sometimes, if you have a specialized environment or use case, the maintainers
   may ask for your help testing the patch.

6. The issue is closed.



## Setting up Go

If you have never worked with Go before, you will have to install its
runtime in order to build packer with the Qemu plugin.

1. This project always releases from the latest version of golang.
[Install go](https://golang.org/doc/install#install) To properly build from
source, you need to have golang >= 1.18

## Setting up Qemu plugin for dev

With Go installed, you can already `go get` the Qemu plugin and `make dev` in
order to compile and test it. These instructions target
POSIX-like environments (macOS, Linux, Cygwin, etc.) so you may need to
adjust them for Windows or other shells.

1. Download the Qemu plugin source (and its dependencies) by running
   `go get github.com/hashicorp/packer-plugin-qemu`. This will download the source to
   `$GOPATH/src/github.com/hashicorp/packer-plugin-qemu`.

2. When working on the Qemu plugin, first `cd $GOPATH/src/github.com/hashicorp/packer-plugin-qemu`
   so you can run `make dev` and easily access other files. `make dev` will build the packer-plugin-qemu binary and install it under `$HOME/.packer.d/plugins/`.

3. Make your changes to the Qemu plugin source. You can run `make dev` to build and install locally, and `make test` to run unit tests.
   Any compilation errors will be shown when the binaries are rebuilding. If you don't have `make` you can simply run `go build -o packer-plugin-qemu` from the project root, and `mv packer-plugin-qemu ~/.packer.d/plugins/packer-plugin-qemu` to install the plugin.

4. After building the Qemu plugin successfully, use the latest version of Packer to build a machine and verify your changes. In the [example folder](https://github.com/hashicorp/packer-plugin-qemu/blob/main/example) we provide a basic template. Comment out the `packer {}` block to force Packer use the development binary installed in the previous step.

5. If everything works well and the tests pass, run `go fmt ./...` on your code before
   submitting a pull-request.


### Opening a Pull Request

Thank you for contributing! When you are ready to open a pull-request, you will
need to [fork the Qemu plugin](https://github.com/hashicorp/packer-plugin-qemu#fork-destination-box), push your
changes to your fork, and then open a pull-request.

For example, my github username is `myuser`, so I would do the following:

```
git checkout -b f-my-feature
# Develop a patch.
git push https://github.com/myuser/packer-plugin-qemu f-my-feature
```

From there, open your fork in your browser to open a new pull-request.

### Pull Request Lifecycle

1. You are welcome to submit your pull request for commentary or review before
   it is fully completed. Please prefix the title of your pull request with
   "[WIP]" to indicate this. It's also a good idea to include specific questions
   or items you'd like feedback on.

2. Once you believe your pull request is ready to be merged, you can remove any
   "[WIP]" prefix from the title and a core team member will review.

3. One of Qemu plugin's core team members will look over your contribution and
   either merge, or provide comments letting you know if there is anything left
   to do. We do our best to provide feedback in a timely manner, but it may take
   some time for us to respond. We may also have questions that we need answered
   about the code, either because something doesn't make sense to us or because
   we want to understand your thought process.

4. If we have requested changes, you can either make those changes or, if you
   disagree with the suggested changes, we can have a conversation about our
   reasoning and agree on a path forward. This may be a multi-step process. Our
   view is that pull requests are a chance to collaborate, and we welcome
   conversations about how to do things better. It is the contributor's
   responsibility to address any changes requested. While reviewers are happy to
   give guidance, it is unsustainable for us to perform the coding work necessary
   to get a PR into a mergeable state.

5. Once all outstanding comments and checklist items have been addressed, your
   contribution will be merged! Merged PRs will be included in the next
   Packer release. The core team takes care of updating the
   [CHANGELOG.md](../CHANGELOG.md) as they merge.

6. In rare cases, we might decide that a PR should be closed without merging.
   We'll make sure to provide clear reasoning when this happens.

### Tips for Working on Packer

#### Getting Your Pull Requests Merged Faster

It is much easier to review pull requests that are:

1. Well-documented: Try to explain in the pull request comments what your
   change does, why you have made the change, and provide instructions for how
   to produce the new behavior introduced in the pull request. If you can,
   provide screen captures or terminal output to show what the changes look
   like. This helps the reviewers understand and test the change.

2. Small: Try to only make one change per pull request. If you found two bugs
   and want to fix them both, that's _awesome_, but it's still best to submit
   the fixes as separate pull requests. This makes it much easier for reviewers
   to keep in their heads all of the implications of individual code changes,
   and that means the PR takes less effort and energy to merge. In general, the
   smaller the pull request, the sooner reviewers will be able to make time to
   review it.

3. Passing Tests: Based on how much time we have, we may not review pull
   requests which aren't passing our tests. (Look below for advice on how to
   run unit tests). If you need help figuring out why tests are failing, please
   feel free to ask, but while we're happy to give guidance it is generally
   your responsibility to make sure that tests are passing. If your pull request
   changes an interface or invalidates an assumption that causes a bunch of
   tests to fail, then you need to fix those tests before we can merge your PR.

If we request changes, try to make those changes in a timely manner. Otherwise,
PRs can go stale and be a lot more work for all of us to merge in the future.

Even with everyone making their best effort to be responsive, it can be
time-consuming to get a PR merged. It can be frustrating to deal with
the back-and-forth as we make sure that we understand the changes fully. Please
bear with us, and please know that we appreciate the time and energy you put
into the project.

#### Working on forks

The easiest way to work on a fork is to set it as a remote of the the Qemu plugin
project. After following the steps in "Setting up Go to work on the Qemu plugin":

1. Navigate to the code:

   `cd $GOPATH/src/github.com/hashicorp/packer-plugin-qemu`

2. Add the remote by running:

   `git remote add <name of remote> <github url of fork>`

   For example:

   `git remote add myuser https://github.com/myuser/packer-plugin-qemu.git`

3. Checkout a feature branch:

   `git checkout -b new-feature`

4. Make changes.
5. (Optional) Push your changes to the fork:

   `git push -u <name of remote> new-feature`

This way you can push to your fork to create a PR, but the code on disk still
lives in the spot where the go cli tools are expecting to find it.

#### Go modules & go vendor

If you are submitting a change that requires new or updated dependencies,
please include them in `go.mod`/`go.sum`. This
helps everything get tested properly in CI.

Note that you will need to use [go
mod](https://github.com/golang/go/wiki/Modules) to do this. This step is
recommended but not required.

Use `go get <project>` to add dependencies to the project. See [go mod quick
start](https://github.com/golang/go/wiki/Modules#quick-start) for examples.

Please only apply the minimal vendor changes to get your PR to work. The Qemu plugin
does not attempt to track the latest version for each dependency.

#### HCL2 Spec code generation

Packer relies on `go generate` to generate HCL2's bridging code. First you should install the command with `go install github.com/hashicorp/packer-plugin-sdk/cmd/packer-sdc@latest`, then you generate with
`go generate ./...`. This should update/create `*.hcl2spec.go` file(s).

#### Running Unit Tests

To run unit tests, simply call

```
make test
```

from the plugin's project root.

#### Running Builder Acceptance Tests

If the Qemu Plugin has [acceptance tests](https://en.wikipedia.org/wiki/Acceptance_testing), these probably have some requirements such as environment variables to be set for API tokens and keys. Each test should error and tell you what are missing, so those are not documented here.

If you're working on a feature and want to verify it is functioning (and also hasn't broken anything else), we recommend creating or running the acceptance tests.

**Warning:** The acceptance tests create/destroy/modify _real resources_, which
may incur costs for real money. In the presence of a bug, it is possible that
resources may be left behind, which can cost money even though you were not
using them. We recommend running tests in an account used only for that purpose
so it is easy to see if there are any dangling resources, and so production
resources are not accidentally destroyed or overwritten during testing.

To run the acceptance tests, invoke `make testacc`:

```
make testacc
...
```

The `TEST` variable lets you narrow the scope of the acceptance tests to a
specific package / folder.

#### Debugging Plugins

Each packer plugin runs in a separate process and communicates via RPC over a
socket therefore using a debugger will not work (be complicated at least).

The Packer and plugins code provides more detailed logs when ran with PACKER_LOG
turned on. If that doesn't work, adding some extra debug print outs when you have
homed in on the problem is usually enough.
