virtualgo

Virtualgo (or vg for short) is a tool which provides workspace based development for Go. Its main feature set that makes it better than other solutions is as follows:

1. Extreme ease of use
2. No interference with other go tools
3. Version pinning for imports
4. Version pinning for executables, such as linters (e.g. errcheck) and codegen tools (e.g. protoc-gen-go)
5. Importing a dependency that's locally checked out outside of the workspace (also called multi project workflow)
6. Optional full isolation for imports, see the section on import modes for details.

Virtualgo doesn't do dependency resolution or version pinning itself, because this is a hard problem that's already being solved by other tools. Its approach is to build on top of these tools, such as dep, to provide the features features listed above. For people coming from Python vg is very similar to virtualenv, with dep being respective to pip. The main difference is that vg is much easier to use than virtualenv, because there's almost no mental overhead in using vg.

Go Modules

The Go community is now using Go Modules to handle dependencies. This project is now mostly unmaintained. Please read more about this here.

Example usage

Below is an example showing some basic usage of vg. See further down and vg help for more information and examples.

$ cd $GOPATH/src/github.com/GetStream/example
$ vg init  # initial creation of workspace

# Now all commands will be executed from within the example workspace
(example) $ go get github.com/pkg/errors # package only present in workspace
(example) $ vg ensure  # installs the dependencies of the example project using dep
(example) $ vg deactivate

$ cd ~
$ cd $GOPATH/src/github.com/GetStream/example
(example) $ # The workspace is now activated automatically after cd-ing to the project directory

Advantages over existing solutions

The obvious question is: Why should you use vg? What advantages does it bring over what you're using now? This obviously depends on what you're using now:

Advantages over vendor directory

1. You can pin versions of executable dependencies, such as linting and code generation tools.
2. No more issues with go test ./... running tests in the vendor directory when using go 1.8 and below.
3. You can easily use a dependency from your global GOPATH inside your workspace, without running into confusing import errors.
4. It has optional full isolation. If enabled there's no accidental fallbacks to regular GOPATH causing confusion about what version of a package you're using.
5. When using full isolation, tools such as IDEs can spend much less time on indexing. This is simply because they don't have to index the packages outside the workspace.
6. You don't have problems when using plugins: https://github.com/akutz/gpd

Advantages over manually managing multiple GOPATHs

1. Automatic activation of a GOPATH when you cd into a directory.
2. Integration with version management tools such as dep and glide allow for reproducible builds.
3. Useful commands to manage installed packages. For instance for uninstalling a package or installing a local package from another GOPATH.

Installation

First install the package:

go get -u github.com/GetStream/vg

Although not required, it is recommended to install bindfs as well. This gives the best experience when using full isolation and when using vg localInstall. If you do this, DON'T remove things manually from ~/.virtualgo. Only use vg destroy/vg uninstall, otherwise you can very well lose data.

# OSX
brew install bindfs
# Ubuntu
apt install bindfs
# Arch Linux
pacaur -S bindfs  # or yaourt or whatever tool you use for AUR

Automatic shell configuration

You can run the following command to configure all supported shells automatically:

vg setup

After this you have to reload (source) your shell configuration file:

source ~/.bashrc                   # for bash
source ~/.zshrc                    # for zsh
source ~/.config/fish/config.fish  # for fish

Manual shell configuration

You can also edit your shell configuration file manually. Afterwards you still have to source the file like explained above.

For bash put this in your ~/.bashrc file:

command -v vg >/dev/null 2>&1 && eval "$(vg eval --shell bash)"

Or for zsh, put his in your ~/.zshrc file:

command -v vg >/dev/null 2>&1 && eval "$(vg eval --shell zsh)"

Or for fish, put this in your ~/.config/fish/config.fish file:

command -v vg >/dev/null 2>&1; and vg eval --shell fish | source

Usage

The following commands are the main commands to use vg:

# The first command to use is the one to create and activate a workspace named
# after the current direcory
$ cd $GOPATH/src/github.com/GetStream/example
$ vg init
(example) $
# This command also links the current directory to the created workspace. This
# way the next time you cd to this directory the workspace will be activated
# automatically.
# (See below in the README on how to use the workspace from an IDE)

# All go commands in this shell are now executed from within your workspace. The
# following will install the most recent version of the cobra command and
# library inside the workspace
(example) $ go get -u github.com/spf13/cobra/cobra
(example) $ cobra
Cobra is a CLI library for Go that empowers applications.
......

# It's also possible to only activate a workspace and not link it to the
# current directory. If the workspace doesn't exist it will also be
# created on the fly. Activating a new workspace automatically deactivates
# a previous one:
(example) $ vg activate example2
(example2) $ cobra
bash: cobra: command not found

# To deactivate the workspace simply run:
(example2) $ vg deactivate
$ vg activate
(example) $

# When a workspace is active, a go compilation will try to import packages
# installed from the workspace first. In some cases you might want to use the
# version of a package that is installed in your global GOPATH though. For
# instance when you are fixing a bug in a dependency and want to test the fix.
# In these cases you can easily install a package from your global GOPATH
# into the workspace:
(example) $ vg localInstall github.com/GetStream/utils
# You can even install a package from a specific path:
(example) $ vg localInstall github.com/GetStream/utils ~/weird/path/utils

# You can also uninstall a package from your workspace again
(example) $ vg uninstall github.com/spf13/cobra
# NOTE: At the moment this only removes the sources and static libs in pkg/, not
# executables. So the cobra command is still available.

# See the following sections for integration with dependency management tools.
# And for a full overview of all commands just run:
(example) $ vg help
# For detailed help of a specific command run:
(example) $ vg help <command>

dep integration

vg integrates well with dep (https://github.com/golang/dep):

# Install the dependencies from Gopkg.lock into your workspace instead of the
# vendor directory
vg ensure

# Pass options to `dep ensure`
vg ensure -- -v -update

It also extends dep with a way to install executable dependencies. The vg repo itself uses it to install the go-bindata and cobra command. It does this by adding the following in Gopkg.toml:

required = [
    'github.com/jteeuwen/go-bindata/go-bindata',
    'github.com/spf13/cobra/cobra'
]

Running vg ensure after adding this will install the go-bindata and cobra command in the GOBIN of the current workspace.

As you just saw vg reuses the required list from dep. However, if you don't want to install all packages in the required list you can achieve that by putting the following in Gopkg.toml:

[metadata]
install-required = false

You can also specify which packages to install without the required list:

[metadata]
install = [
    'github.com/jteeuwen/go-bindata/go-bindata',
    'github.com/golang/mock/...', # supports pkg/... syntax
]

Integration with other dependency management tools (e.g glide)

Even though dep is the main tool that virtualgo integrates with. It's also possible to use other dependency management tools instead, as long as they create a vendor directory. Installing executable dependencies is not supported though (PRs for this are welcome).

To use vg with glide works like this:

# Install dependencies into vendor with glide
glide install

# Move these dependencies into the workspace
vg moveVendor

Workspace import modes

A workspace can be set up in two different import modes, global fallback or full isolation. The import mode of a workspace determines how imports from code behave and it is chosen when the workspace is created.

Global fallback

In global fallback mode, packages are imported from the original GOPATH when they are not found in the workspace. This is the default import mode for newly created workspaces, as this interferes the least with existing go tools.

Full isolation

In full isolation mode, package imports will only search in the packages that are installed inside the workspace. This has some advantages:

1. Tools such as IDE's don't have to search the global GOPATH for imports, which can result in a significant speedup for operations such as indexing.
2. You always know the location of an imported package.
3. It's not possible to accidentally import of a package that is not managed by your vendoring tool of choice.

However, there's also some downsides to full isolation of a workspace. These are all caused by the fact that the project you're actually working on is not inside your GOPATH anymore. So normally go would not be able to find any imports to it. This is partially worked around by locally installing the project into your workspace, but it does not fix all issues.

In the sections below the remaining issues are described and you can decide for yourself if the above advantages are worth the disadvantages. If you want to try out full isolation you can create a new workspace using the --full-isolation flag:

$ vg init --full-isolation
# To change an existing workspace, you have to destroy and recreate it
$ vg destroy example
$ vg activate example --full-isolation

This will cause the workspace to use full isolation import mode each time it is activated in the future. So there's no need to specify the --full-isolation flag on each activation afterwards.

With bindfs installed

If you have bindfs installed the issues you will run into are only a slight inconvenience, for which easy workarounds exist. However, it is important that you know about them, because they will probably cause confusion otherwise. If you run into any other issues than the ones mentioned here, please report them.

Relative packages in commands

The first set of issues happen when using relative reference to packages in commands. Some examples of this are:

• go list ./... will return weirdly formatted paths, such as _/home/stream/go/src/github.com/GetStream/vg.
• go test ./..., might cause an init function to be executed twice.
• go build ./... won't work when an internal package is present in the directory. Here you can expect an error saying use of internal package not allowed.

Luckily, this can all easily be worked around by using absolute package paths for these commands. So for the vg repo you would use the following alternatives:

# go list ./...
go list github.com/GetStream/vg/...
# go test ./...
go test github.com/GetStream/vg/...
# go build ./...
go build github.com/GetStream/vg/...

dep commands

Another issue that pops up is that dep doesn't allow it's commands to be executed outside of the GOPATH. This is not a problem for dep ensure, since you usually use vg ensure, which handles this automatically. However, this is an issue for other commands, such as dep status and dep init. Luckily there's an easy workaround for this as well. You can simply use vg globalExec, to execute commands from your regular GOPATH, which fixes the issue:

vg globalExec dep init
vg globalExec dep status

Without bindfs installed

If bindfs is not installed, symbolic links will be used to do the local install. This has the same issues as described for bindfs, but there's also some extra ones that cannot be worked around as easily. The reason for this is that go tooling does not like symbolic links in GOPATH (golang/go#15507, golang/go#17451).

Compiling will still work, but go list github.com/... will not list your package. Other than that there are also issues when using delve (#11). Because of these issues it is NOT RECOMMENDED to use virtualgo in full isolation mode without bindfs installed.

Using a virtualgo workspace with an IDE (e.g. GoLand)

Because virtualgo is just a usability wrapper around changing your GOPATH for a specific project it is usually quite easy to use it in combination with an IDE. Just check out your GOPATH after activating a workspace and configure the IDE accordingly. Usually if you show your GOPATH you will see two paths separated by a colon:

$ echo $GOPATH
/home/stream/.virtualgo/myworkspace:/home/stream/go

If you can set this full string directly that is fine. For GoLand you have to add the first one first and then the second one.

When using a workspace in full isolation mode it's even easier to set up as there's only one GOPATH set.

$ echo $GOPATH
/home/stream/.virtualgo/myworkspace

License

MIT

Careers @ Stream

Would you like to work on cool projects like this? We are currently hiring for talented Gophers in Amsterdam and Boulder, get in touch with us if you are interested! tommaso@getstream.io