Hi wave How do I import a local module in a Lua script used

Question

Hi wave How do I import a local module in a Lua script used for a LakeFS hook So I declared a lakefs hook as follows ```name test action hooks id test hook type lua properties script path scripts test script lua``` and I placed my Lua script under the ` script ` prefix in my repo and also added another module `mymodule lua` under that same prefix ``` scripts test script lua mymodule lua``` and I want to import and use `mymodule` in `test script lua` and I tried a few things but I keep getting module not found errors I m not very familiar with Lua so I m not sure if this is a Lua programming thing or if it s related to where the scripts are stored and organized in Lakefs server Any help with this is greatly appreciated

Itai Admi · Answer

Hi Taha that s a great question Not sure if I ve seen an example of Lua module sharing in lakeFS Let me find out and update this thread

Oz Katz · Answer

Good question indeed Unfortunately this is currently <https github com treeverse lakeFS blob e63bf51273bfcb1d8f01f25118b94702e5062193 pkg actions lua stdlib go L357|not supported> We intentionally disable any external IO to be made by the executing script The reasoning is security this increases the surface area of what a Lua script could do In the case of module imports it means validating the entire dependency graph for read permissions The executing hook would need to be able to read the loaded module and any module loaded by that loaded module while possible it adds complexity and requires through testing so wasn t prioritized until now Could you elaborate a bit about the use case

Taha Sadiki · Answer

I see the use case is that I m implementing multiple Lakefs Actions and Hooks that share some of the same functionality So packaging that common functionality in a separate shared module for code reuse will improve maintainability compared to copy pasting the same logic in multiple places

Taha Sadiki · Answer

What if we require the users to explicitly define the dependencies when declaring the Action Something like ```name test action hooks id test hook type lua properties script path scripts test script lua script dependencies script mymodule lua``` and then only allow importing from those declared dependencies I m wondering if that would reduce the security risk and simplify managing permissions

Oz Katz · Answer

Possibly definitely worth looking into such an approach perhaps something similar to python s `sys path` could be adapted to this

Oz Katz · Answer

An approach that I could suggest for now which is not the most elegant is a big mono file including all the hooks You can then pass a `properties args run` flag that accepts a name of a function to run This has the benefit of only having to maintain one copy of shared code but is probably not as easy to maintain as proper modules Here s an example of what that might look like ```name Execute Things description do things on post commit hooks id do stuff type lua properties script path scripts run stuff lua args run this function``` With the script simply executing the passed function ```function this function print doing this end function that function print doing that end actions = this function = this function that function = that function actions args run ``` Would that be helpful as an interim solution

Taha Sadiki · Answer

that s an interesting idea I worry that we ll be mixing too many concerns in the same big file But I think it s definitely worth considering especially if the different hooks share a significant amount of logic