remod

remod

DEPRECATED: Go devs, after dismissing the use case remod was solving, finally implemented a native way to do what remod was doing with go workspaces. So this repository is now deprecated and won't get any new updates.

remod is a tool to work with local copies of libraries and go modules. It provides a cli to manage replacement directives in a file called remod.dev that can be ignored from VSC. Remod also uses git attributes to make the changes applied to the go.mod file completely transparent.

When you work on projects with various internal libraries that are working closely together, you usually need to have a bit of velocity. For example, the Aporeto ci pipelines are able combine multiple pull requests accross multiple github repositories to test them together.

While go modules help in a lot of scenarios, being able to do such things is not one them. remod made that workflow easier by selectively restoring the GOPATH behavior on only a subset of the dependencies, while benefiting from go modules for the others.

Installation

To install remod, run:

go get go.aporeto.io/remod

Working with remod

Initialization

If you never used remod on that repo, you need to first run:

remod init

This will add a the necessary .gitattributes, and configure your clone to ignore the relevant changes in the go.mod and go.sum files.

You can then edit the remod.dev file with the replacements you want. You can also decide to preconfigure the replacements using the --include and --exclude flags.

The modules you pass are actually used as prefix, so you can replace all the packages from github.com/spf13 by doing:

remod init -m github.com/spf13

Which will modify the remod.dev file like so:

replace (
  github.com/spf13/cobra => ../cobra
  github.com/spf13/viper => ../viper
)

To set a different base path, you can use the option --prefix.

For instance:

remod init -m github.com/spf13/viper --prefix github.com/me/ --replace-version dev

Which will turn the remod.dev file to:

replace (
  github.com/spf13/viper => github.com/me/viper dev
)

It is safe to edit the remod.dev file manually as you wish.

Activating remod for the branch

Note: If you've cloned a fresh repo, or switched to a new branch, you need to run remod on again before being able to use it. Running remod on is idempotent and will align what needs to be aligned.

remod allows to switch on and off the development mode at will, where it will add replace directives from remod.dev file in your go.mod file.

For instance, if we have the following go.mod:

module go.aporeto.io/remod

go 1.12

require (
  github.com/spf13/cobra v0.0.5
  github.com/spf13/viper v1.4.0
)

And remod.dev contains:

replace github.com/spf13/viper => ../viper

You can enable the development mode by running:

remod on

The go.mod file will now look like:

module go.aporeto.io/remod

go 1.12

require (
  github.com/spf13/cobra v0.0.5
  github.com/spf13/viper v1.4.0
)

// remod:start

replace github.com/spf13/viper => ../viper

// remod:end

You should see no change from the git point of view.

Updating or installing new modules

If you need to update or add a new module that must end up in the final go.mod you need to run the following command:

remod get github.com/user/repo

This will transparently restore the original go.mod, run the add the new dependency, and reactivate the development mode. If development mode was not active, it will work as usual.

remod get will blindly pass all arguments to the underlying go get command, so anything supported by go get command can be done through remod.

Note: if you simply run go get while remod is on, you will loose the change.

Deactivating remod for the branch

You cam turn off the development mode for the current branch by running:

remod off

This will restore the original go.mod and go.sum file. Note that this only affects the current branch. You can run remod on again at any time to start development mode again.

Updating modules in bulk

The command remod update allows to update all modules with a prefix at once.

For instance, to update all modules from go.aporeto.io in the current project, you can run:

remod up go.aporeto.io

It will udpate the the latest tag by default.

You can change this behavior by setting the --version flag, and exclude some modules with the --exclude flag.

For instance:

remod up go.aporeto.io --version master --exclude go.aporeto.io/trireme-lib