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Overriding vendor

The vendor directory is immutable in its nature. You can’t and should never modify any files inside of it, jb will revert those changes on the next run anyway.

Nevertheless, it can sometimes become required to add changes there, e.g. if an upstream library contains a bug that needs to be fixed immediately, without waiting for the upstream maintainer to review it.


Because import paths are ranked in Tanka, you can use a technique called shadowing: By putting a file with the exact same name in a higher ranked path, Tanka will prefer that file instead of the original in vendor, which has the lowest possible rank of 1.

For example, if /vendor/foo/bar.libsonnet contained an error, you could create /lib/foo/bar.libsonnet and fix it there.

Per environment

Another common case is overriding the entire vendor bundle per environment.

This is handy, when you for example want to test a change of an upstream library which is used in many environments (including prod) in a single one, without affecting all the others.

For this, Tanka lets you have a separate vendor, jsonnetfile.json and jsonnetfile.lock.json per environment. To do so:

Create tkrc.yaml

Tanka normally uses the jsonnetfile.json from your project to find its root. As we are going to create another one of that down the tree in the next step, we need another marker for <rootDir>.

For that, create an empty file called tkrc.yaml in your project’s root, alongside the original jsonnetfile.json.

Add a vendor to your environment

In your environments folder (e.g. /environments/default):

Terminal window
# init jsonnet bundler (creates jsonnetfile.json)
jb init
# install the updated dependency
jb install