mirror of https://github.com/kubernetes/kops.git
62 lines
2.7 KiB
Markdown
62 lines
2.7 KiB
Markdown
# Go dependency management in kops
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There is (currently) no perfect solution for dependency management in go; an "official"
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solution is planned, but in the meantime we use a solution based on git submodules.
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The biggest problem is the double-import problem, where a vendored dependency
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has a `vendor` directory. There is no way to "flatten" the imports.
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See for example the discussion [here](https://github.com/dpw/vendetta/issues/13)
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## The current solution
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* We use git submodules to specify our dependencies. This allows simple (if tedious) direct specification of dependencies without extra tooling.
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* We want to ignore the `vendor` directories in our dependencies though. There is no way to do a "filtered" git submodule.
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* We therefore put the git submodules them into `_vendor`, as this is ignored by go for historical reasons.
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* We then rsync the subset of files we want into `vendor` (via `make copydeps`)
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* We commit the contents of the `vendor` directory to git
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## Shortcomings
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* We have to manually manage our dependencies (this is arguably also an advantage, in the absence of any real rules to resolve conflicts)
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* `go get` will fetch the submodules, so we pull a lot more data than we need to
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## Adding a dependency
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1. Add dependency as a submodule in the `_vendor` directory.
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2. Make sure you have all the git submodules populated. If not you can run `git submodule init` and `git submodule update`.
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3. Run `make copydeps`.
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4. The make command should move the new dependency (and all other current dependencies) into the `vendor` folder, ignoring each submodules own `vendor` directory.
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5. Commit your changes.
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Here is an example of us adding the `go-md2man` package and it's required dependencies:
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```
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git submodule add https://github.com/cpuguy83/go-md2man.git _vendor/github.com/cpuguy83/go-md2man
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git submodule add https://github.com/russross/blackfriday.git _vendor/github.com/russross/blackfriday
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git submodule add https://github.com/shurcooL/sanitized_anchor_name.git _vendor/github.com/shurcooL/sanitized_anchor_name
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git submodule init
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git submodule update
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make copydeps
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git add .gitmodules
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git add _vendor/github.com/cpuguy83/go-md2man
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git add _vendor/github.com/russross/blackfriday
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git add _vendor/github.com/shurcooL/sanitized_anchor_name
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git add vendor/github.com/cpuguy83/go-md2man
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git add vendor/github.com/russross/blackfriday
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git add vendor/github.com/shurcooL/sanitized_anchor_name
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git commit -m "Add go-md2man, blackfriday and sanitized_anchor_name deps"
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```
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## Updating a dependency
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```
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pushd _vendor/github.com/aws/aws-sdk-go
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git fetch
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git checkout v1.5.2
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popd
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make copydeps
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git add _vendor/github.com/aws/aws-sdk-go/
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git add vendor/github.com/aws/aws-sdk-go/
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git commit -m "Update aws-sdk-go to 1.5.2"
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``` |