rclone/CONTRIBUTING.md

# Contributing to rclone

This is a short guide on how to contribute things to rclone.

## Reporting a bug

If you've just got a question or aren't sure if you've found a bug
then please use the [rclone forum](https://forum.rclone.org/) instead
of filing an issue.

When filing an issue, please include the following information if
possible as well as a description of the problem.  Make sure you test
with the [latest beta of rclone](https://beta.rclone.org/):

- Rclone version (e.g. output from `rclone version`)
- Which OS you are using and how many bits (e.g. Windows 10, 64 bit)
- The command you were trying to run (e.g. `rclone copy /tmp remote:tmp`)
- A log of the command with the `-vv` flag (e.g. output from `rclone -vv copy /tmp remote:tmp`)
    - if the log contains secrets then edit the file with a text editor first to obscure them

## Submitting a new feature or bug fix

If you find a bug that you'd like to fix, or a new feature that you'd
like to implement then please submit a pull request via GitHub.

If it is a big feature, then [make an issue](https://github.com/rclone/rclone/issues) first so it can be discussed.

To prepare your pull request first press the fork button on [rclone's GitHub
page](https://github.com/rclone/rclone).

Then [install Git](https://git-scm.com/downloads) and set your public contribution [name](https://docs.github.com/en/github/getting-started-with-github/setting-your-username-in-git) and [email](https://docs.github.com/en/github/setting-up-and-managing-your-github-user-account/setting-your-commit-email-address#setting-your-commit-email-address-in-git).

Next open your terminal, change directory to your preferred folder and initialise your local rclone project:

    git clone https://github.com/rclone/rclone.git
    cd rclone
    git remote rename origin upstream
      # if you have SSH keys setup in your GitHub account:
    git remote add origin git@github.com:YOURUSER/rclone.git
      # otherwise:
    git remote add origin https://github.com/YOURUSER/rclone.git

Note that most of the terminal commands in the rest of this guide must be executed from the rclone folder created above.

Now [install Go](https://golang.org/doc/install) and verify your installation:

    go version

Great, you can now compile and execute your own version of rclone:

    go build
    ./rclone version

(Note that you can also replace `go build` with `make`, which will include a
more accurate version number in the executable as well as enable you to specify
more build options.) Finally make a branch to add your new feature

    git checkout -b my-new-feature

And get hacking.

You may like one of the [popular editors/IDE's for Go](https://github.com/golang/go/wiki/IDEsAndTextEditorPlugins) and a quick view on the rclone [code organisation](#code-organisation).

When ready - test the affected functionality and run the unit tests for the code you changed

    cd folder/with/changed/files
    go test -v

Note that you may need to make a test remote, e.g. `TestSwift` for some
of the unit tests.

This is typically enough if you made a simple bug fix, otherwise please read the rclone [testing](#testing) section too.

Make sure you

- Add [unit tests](#testing) for a new feature.
- Add [documentation](#writing-documentation) for a new feature.
- [Commit your changes](#committing-your-changes) using the [commit message guidelines](#commit-messages).

When you are done with that push your changes to GitHub:

    git push -u origin my-new-feature

and open the GitHub website to [create your pull
request](https://help.github.com/articles/creating-a-pull-request/).

Your changes will then get reviewed and you might get asked to fix some stuff. If so, then make the changes in the same branch, commit and push your updates to GitHub.

You may sometimes be asked to [base your changes on the latest master](#basing-your-changes-on-the-latest-master) or [squash your commits](#squashing-your-commits).

## Using Git and GitHub

### Committing your changes

Follow the guideline for [commit messages](#commit-messages) and then:

    git checkout my-new-feature      # To switch to your branch
    git status                       # To see the new and changed files
    git add FILENAME                 # To select FILENAME for the commit
    git status                       # To verify the changes to be committed
    git commit                       # To do the commit
    git log                          # To verify the commit. Use q to quit the log

You can modify the message or changes in the latest commit using:

    git commit --amend

If you amend to commits that have been pushed to GitHub, then you will have to [replace your previously pushed commits](#replacing-your-previously-pushed-commits).

### Replacing your previously pushed commits

Note that you are about to rewrite the GitHub history of your branch. It is good practice to involve your collaborators before modifying commits that have been pushed to GitHub.

Your previously pushed commits are replaced by:

    git push --force origin my-new-feature 

### Basing your changes on the latest master

To base your changes on the latest version of the [rclone master](https://github.com/rclone/rclone/tree/master) (upstream):

    git checkout master
    git fetch upstream
    git merge --ff-only
    git push origin --follow-tags    # optional update of your fork in GitHub
    git checkout my-new-feature
    git rebase master

If you rebase commits that have been pushed to GitHub, then you will have to [replace your previously pushed commits](#replacing-your-previously-pushed-commits).

### Squashing your commits ###

To combine your commits into one commit:

    git log                          # To count the commits to squash, e.g. the last 2
    git reset --soft HEAD~2          # To undo the 2 latest commits
    git status                       # To check everything is as expected

If everything is fine, then make the new combined commit:

    git commit                       # To commit the undone commits as one

otherwise, you may roll back using:

    git reflog                       # To check that HEAD{1} is your previous state
    git reset --soft 'HEAD@{1}'      # To roll back to your previous state

If you squash commits that have been pushed to GitHub, then you will have to [replace your previously pushed commits](#replacing-your-previously-pushed-commits).

Tip: You may like to use `git rebase -i master` if you are experienced or have a more complex situation.

### GitHub Continuous Integration

rclone currently uses [GitHub Actions](https://github.com/rclone/rclone/actions) to build and test the project, which should be automatically available for your fork too from the `Actions` tab in your repository.

## Testing

### Code quality tests

If you install [golangci-lint](https://github.com/golangci/golangci-lint) then you can run the same tests as get run in the CI which can be very helpful.

You can run them with `make check` or with `golangci-lint run ./...`.

Using these tests ensures that the rclone codebase all uses the same coding standards. These tests also check for easy mistakes to make (like forgetting to check an error return).

### Quick testing

rclone's tests are run from the go testing framework, so at the top
level you can run this to run all the tests.

    go test -v ./...

You can also use `make`, if supported by your platform

    make quicktest

The quicktest is [automatically run by GitHub](#github-continuous-integration) when you push your branch to GitHub.

### Backend testing

rclone contains a mixture of unit tests and integration tests.
Because it is difficult (and in some respects pointless) to test cloud
storage systems by mocking all their interfaces, rclone unit tests can
run against any of the backends.  This is done by making specially
named remotes in the default config file.

If you wanted to test changes in the `drive` backend, then you would
need to make a remote called `TestDrive`.

You can then run the unit tests in the drive directory.  These tests
are skipped if `TestDrive:` isn't defined.

    cd backend/drive
    go test -v

You can then run the integration tests which test all of rclone's
operations.  Normally these get run against the local file system,
but they can be run against any of the remotes.

    cd fs/sync
    go test -v -remote TestDrive:
    go test -v -remote TestDrive: -fast-list

    cd fs/operations
    go test -v -remote TestDrive:

If you want to use the integration test framework to run these tests
altogether with an HTML report and test retries then from the
project root:

    go install github.com/rclone/rclone/fstest/test_all
    test_all -backends drive

### Full integration testing

If you want to run all the integration tests against all the remotes,
then change into the project root and run

    make check
    make test

The commands may require some extra go packages which you can install with

    make build_dep

The full integration tests are run daily on the integration test server. You can
find the results at https://pub.rclone.org/integration-tests/

## Code Organisation

Rclone code is organised into a small number of top level directories
with modules beneath.

- backend - the rclone backends for interfacing to cloud providers -
    - all - import this to load all the cloud providers
    - ...providers
- bin - scripts for use while building or maintaining rclone
- cmd - the rclone commands
    - all - import this to load all the commands
    - ...commands
- cmdtest - end-to-end tests of commands, flags, environment variables,...
- docs - the documentation and website
    - content - adjust these docs only - everything else is autogenerated
    - command - these are auto-generated - edit the corresponding .go file
- fs - main rclone definitions - minimal amount of code
    - accounting - bandwidth limiting and statistics
    - asyncreader - an io.Reader which reads ahead
    - config - manage the config file and flags
    - driveletter - detect if a name is a drive letter
    - filter - implements include/exclude filtering
    - fserrors - rclone specific error handling
    - fshttp - http handling for rclone
    - fspath - path handling for rclone
    - hash - defines rclone's hash types and functions
    - list - list a remote
    - log - logging facilities
    - march - iterates directories in lock step
    - object - in memory Fs objects
    - operations - primitives for sync, e.g. Copy, Move
    - sync - sync directories
    - walk - walk a directory
- fstest - provides integration test framework
    - fstests - integration tests for the backends
    - mockdir - mocks an fs.Directory
    - mockobject - mocks an fs.Object
    - test_all - Runs integration tests for everything
- graphics - the images used in the website, etc.
- lib - libraries used by the backend
    - atexit - register functions to run when rclone exits
    - dircache - directory ID to name caching
    - oauthutil - helpers for using oauth
    - pacer - retries with backoff and paces operations
    - readers - a selection of useful io.Readers
    - rest - a thin abstraction over net/http for REST
- librclone - in memory interface to rclone's API for embedding rclone
- vfs - Virtual FileSystem layer for implementing rclone mount and similar

## Writing Documentation

If you are adding a new feature then please update the documentation.

If you add a new general flag (not for a backend), then document it in
`docs/content/docs.md` - the flags there are supposed to be in
alphabetical order.

If you add a new backend option/flag, then it should be documented in
the source file in the `Help:` field.

- Start with the most important information about the option,
    as a single sentence on a single line.
    - This text will be used for the command-line flag help.
    - It will be combined with other information, such as any default value,
      and the result will look odd if not written as a single sentence.
    - It should end with a period/full stop character, which will be shown
      in docs but automatically removed when producing the flag help.
    - Try to keep it below 80 characters, to reduce text wrapping in the terminal.
- More details can be added in a new paragraph, after an empty line (`"\n\n"`).
    - Like with docs generated from Markdown, a single line break is ignored
      and two line breaks creates a new paragraph.
    - This text will be shown to the user in `rclone config`
      and in the docs (where it will be added by `make backenddocs`,
      normally run some time before next release).
- To create options of enumeration type use the `Examples:` field.
    - Each example value have their own `Help:` field, but they are treated
      a bit different than the main option help text. They will be shown
      as an unordered list, therefore a single line break is enough to
      create a new list item. Also, for enumeration texts like name of
      countries, it looks better without an ending period/full stop character.

The only documentation you need to edit are the `docs/content/*.md`
files.  The `MANUAL.*`, `rclone.1`, website, etc. are all auto-generated
from those during the release process.  See the `make doc` and `make
website` targets in the Makefile if you are interested in how.  You
don't need to run these when adding a feature.

Documentation for rclone sub commands is with their code, e.g.
`cmd/ls/ls.go`. Write flag help strings as a single sentence on a single
line, without a period/full stop character at the end, as it will be
combined unmodified with other information (such as any default value).

Note that you can use [GitHub's online editor](https://help.github.com/en/github/managing-files-in-a-repository/editing-files-in-another-users-repository)
for small changes in the docs which makes it very easy.

## Making a release

There are separate instructions for making a release in the RELEASE.md
file.

## Commit messages

Please make the first line of your commit message a summary of the
change that a user (not a developer) of rclone would like to read, and
prefix it with the directory of the change followed by a colon.  The
changelog gets made by looking at just these first lines so make it
good!

If you have more to say about the commit, then enter a blank line and
carry on the description.  Remember to say why the change was needed -
the commit itself shows what was changed.

Writing more is better than less.  Comparing the behaviour before the
change to that after the change is very useful.  Imagine you are
writing to yourself in 12 months time when you've forgotten everything
about what you just did and you need to get up to speed quickly.

If the change fixes an issue then write `Fixes #1234` in the commit
message.  This can be on the subject line if it will fit.  If you
don't want to close the associated issue just put `#1234` and the
change will get linked into the issue.

Here is an example of a short commit message:

```
drive: add team drive support - fixes #885
```

And here is an example of a longer one:

```
mount: fix hang on errored upload

In certain circumstances, if an upload failed then the mount could hang
indefinitely. This was fixed by closing the read pipe after the Put
completed.  This will cause the write side to return a pipe closed
error fixing the hang.

Fixes #1498
```

## Adding a dependency

rclone uses the [go
modules](https://tip.golang.org/cmd/go/#hdr-Modules__module_versions__and_more)
support in go1.11 and later to manage its dependencies.

rclone can be built with modules outside of the `GOPATH`.

To add a dependency `github.com/ncw/new_dependency` see the
instructions below.  These will fetch the dependency and add it to
`go.mod` and `go.sum`.

    go get github.com/ncw/new_dependency

You can add constraints on that package when doing `go get` (see the
go docs linked above), but don't unless you really need to.

Please check in the changes generated by `go mod` including `go.mod`
and `go.sum` in the same commit as your other changes.

## Updating a dependency

If you need to update a dependency then run

    go get golang.org/x/crypto

Check in a single commit as above.

## Updating all the dependencies

In order to update all the dependencies then run `make update`.  This
just uses the go modules to update all the modules to their latest
stable release. Check in the changes in a single commit as above.

This should be done early in the release cycle to pick up new versions
of packages in time for them to get some testing.

## Updating a backend

If you update a backend then please run the unit tests and the
integration tests for that backend.

Assuming the backend is called `remote`, make create a config entry
called `TestRemote` for the tests to use.

Now `cd remote` and run `go test -v` to run the unit tests.

Then `cd fs` and run `go test -v -remote TestRemote:` to run the
integration tests.

The next section goes into more detail about the tests.

## Writing a new backend

Choose a name.  The docs here will use `remote` as an example.

Note that in rclone terminology a file system backend is called a
remote or an fs.

### Research

- Look at the interfaces defined in `fs/types.go`
- Study one or more of the existing remotes

### Getting going

- Create `backend/remote/remote.go` (copy this from a similar remote)
    - box is a good one to start from if you have a directory-based remote (and shows how to use the directory cache)
    - b2 is a good one to start from if you have a bucket-based remote
- Add your remote to the imports in `backend/all/all.go`
- HTTP based remotes are easiest to maintain if they use rclone's [lib/rest](https://pkg.go.dev/github.com/rclone/rclone/lib/rest) module, but if there is a really good Go SDK from the provider then use that instead.
- Try to implement as many optional methods as possible as it makes the remote more usable.
- Use [lib/encoder](https://pkg.go.dev/github.com/rclone/rclone/lib/encoder) to make sure we can encode any path name and `rclone info` to help determine the encodings needed
    - `rclone purge -v TestRemote:rclone-info`
    - `rclone test info --all --remote-encoding None -vv --write-json remote.json TestRemote:rclone-info`
    - `go run cmd/test/info/internal/build_csv/main.go -o remote.csv remote.json`
    - open `remote.csv` in a spreadsheet and examine

### Guidelines for a speedy merge

- **Do** use [lib/rest](https://pkg.go.dev/github.com/rclone/rclone/lib/rest) if you are implementing a REST like backend and parsing XML/JSON in the backend.
- **Do** use rclone's Client or Transport from [fs/fshttp](https://pkg.go.dev/github.com/rclone/rclone/fs/fshttp) if your backend is HTTP based - this adds features like `--dump bodies`, `--tpslimit`, `--user-agent` without you having to code anything!
- **Do** follow your example backend exactly - use the same code order, function names, layout, structure. **Don't** move stuff around and **Don't** delete the comments.
- **Do not** split your backend up into `fs.go` and `object.go` (there are a few backends like that - don't follow them!)
- **Do** put your API type definitions in a separate file - by preference `api/types.go`
- **Remember** we have >50 backends to maintain so keeping them as similar as possible to each other is a high priority!

### Unit tests

- Create a config entry called `TestRemote` for the unit tests to use
- Create a `backend/remote/remote_test.go` - copy and adjust your example remote
- Make sure all tests pass with `go test -v`

### Integration tests

- Add your backend to `fstest/test_all/config.yaml`
    - Once you've done that then you can use the integration test framework from the project root:
    - go install ./...
    - test_all -backends remote

Or if you want to run the integration tests manually:

- Make sure integration tests pass with
    - `cd fs/operations`
    - `go test -v -remote TestRemote:`
    - `cd fs/sync`
    - `go test -v -remote TestRemote:`
- If your remote defines `ListR` check with this also
    - `go test -v -remote TestRemote: -fast-list`

See the [testing](#testing) section for more information on integration tests.

### Backend documentation

Add your backend to the docs - you'll need to pick an icon for it from
[fontawesome](http://fontawesome.io/icons/).  Keep lists of remotes in
alphabetical order of full name of remote (e.g. `drive` is ordered as
`Google Drive`) but with the local file system last.

- `README.md` - main GitHub page
- `docs/content/remote.md` - main docs page (note the backend options are automatically added to this file with `make backenddocs`)
    - make sure this has the `autogenerated options` comments in (see your reference backend docs)
    - update them in your backend with `bin/make_backend_docs.py remote`
- `docs/content/overview.md` - overview docs
- `docs/content/docs.md` - list of remotes in config section
- `docs/content/_index.md` - front page of rclone.org
- `docs/layouts/chrome/navbar.html` - add it to the website navigation
- `bin/make_manual.py` - add the page to the `docs` constant

Once you've written the docs, run `make serve` and check they look OK
in the web browser and the links (internal and external) all work.

## Adding a new s3 provider

It is quite easy to add a new S3 provider to rclone.

You'll need to modify the following files

- `backend/s3/s3.go`
    - Add the provider to `providerOption` at the top of the file
    - Add endpoints and other config for your provider gated on the provider in `fs.RegInfo`.
    - Exclude your provider from generic config questions (eg `region` and `endpoint).
    - Add the provider to the `setQuirks` function - see the documentation there.
- `docs/content/s3.md`
    - Add the provider at the top of the page.
    - Add a section about the provider linked from there.
    - Add a transcript of a trial `rclone config` session
        - Edit the transcript to remove things which might change in subsequent versions
    - **Do not** alter or add to the autogenerated parts of `s3.md`
    - **Do not** run `make backenddocs` or `bin/make_backend_docs.py s3`
- `README.md` - this is the home page in github
    - Add the provider and a link to the section you wrote in `docs/contents/s3.md`
- `docs/content/_index.md` - this is the home page of rclone.org
    - Add the provider and a link to the section you wrote in `docs/contents/s3.md`

When adding the provider, endpoints, quirks, docs etc keep them in
alphabetical order by `Provider` name, but with `AWS` first and
`Other` last.

Once you've written the docs, run `make serve` and check they look OK
in the web browser and the links (internal and external) all work.

Once you've written the code, test `rclone config` works to your
satisfaction, and check the integration tests work `go test -v -remote
NewS3Provider:`. You may need to adjust the quirks to get them to
pass. Some providers just can't pass the tests with control characters
in the names so if these fail and the provider doesn't support
`urlEncodeListings` in the quirks then ignore them. Note that the
`SetTier` test may also fail on non AWS providers.

For an example of adding an s3 provider see [eb3082a1](https://github.com/rclone/rclone/commit/eb3082a1ebdb76d5625f14cedec3f5154a5e7b10).

## Writing a plugin

New features (backends, commands) can also be added "out-of-tree", through Go plugins.
Changes will be kept in a dynamically loaded file instead of being compiled into the main binary.
This is useful if you can't merge your changes upstream or don't want to maintain a fork of rclone.

### Usage

 - Naming
   - Plugins names must have the pattern `librcloneplugin_KIND_NAME.so`.
   - `KIND` should be one of `backend`, `command` or `bundle`.
   - Example: A plugin with backend support for PiFS would be called
     `librcloneplugin_backend_pifs.so`.
 - Loading
   - Supported on macOS & Linux as of now. ([Go issue for Windows support](https://github.com/golang/go/issues/19282))
   - Supported on rclone v1.50 or greater.
   - All plugins in the folder specified by variable `$RCLONE_PLUGIN_PATH` are loaded.
   - If this variable doesn't exist, plugin support is disabled.
   - Plugins must be compiled against the exact version of rclone to work.
     (The rclone used during building the plugin must be the same as the source of rclone)

### Building

To turn your existing additions into a Go plugin, move them to an external repository
and change the top-level package name to `main`.

Check `rclone --version` and make sure that the plugin's rclone dependency and host Go version match.

Then, run `go build -buildmode=plugin -o PLUGIN_NAME.so .` to build the plugin.

[Go reference](https://godoc.org/github.com/rclone/rclone/lib/plugin)

[Minimal example](https://gist.github.com/terorie/21b517ee347828e899e1913efc1d684f)