Resolve relative paths to source projects

[eschwartz]

eg. tmsource://../../project.tm2source

[eschwartz]

I have two main use cases for this:

• I am editing style projects on my local machine, which point to source projects (also on my local machine). Once I'm done editing, I deploy the project files to a remote server for generating tiles. Because the file systems differ, I cannot have project files which work on both my local machine and the remote server.
• I have a system which generates project files ("Project Manager"), and saves them to cloud storage. Another system ("Tile Server") downloads the project files, and serves tiles. The Project Manager has no way to know absolute paths on the Tile Server.

I am aware that this format will not work in Mapbox Studio Classic. However, resolving relative paths in tilelive would still be a big help.

I have tested this locally, but I'm a little nervous about breaking functionality that I don't even know about. Do you have any way to run it through some existing projects, and make sure I'm not breaking anything here?

[mojodna]

fromUri should get the same treatment.

[eschwartz]

fixed

[mojodna]

This is definitely a useful thing, though it has me thinking that having to whitelist is a little bit gnarly (and wouldn't catch nested sources, such as those used by tilelive-merge).

In theory, other modules should be able to resolve relative paths based on process.cwd(), but that assumes that references are relative to your working directory not the referencing config and dynamically setting process.cwd() would have unforeseen consequences.

I'm wondering if using a special token (__dirname, which already has meaning within a source file) as the host portion of a URI possibly makes more sense. That would allow tilelive-tmstyle (for example) to replace the token with the project's path before loading it. I.e. tmsource://__dirname/../../project.tm2source referenced from tmstyle:///path/to/whatever.tm2 would be converted to tmsource:///path/to/whatever.tm2/../../project.tm2source before being loaded.

Thoughts?

[eschwartz]

Thanks for the notes.

I agree that the whitelist is a little bit gnarly. There's no way for tilelive-tmstyle to have a definitive list of all available tilelive implementations. It would be a bummer for new implementations not to work, because tilelive-tmstyle didn't hard-code them into its whitelist.

I see what you're saying about confusion with tilelive implementation which don't use the file system. But it seems to me that if you configure your project.yml with a relative source path, you are clearly intending to reference the file system. ie. if I look at my project.yml and see source: tilelive-http://../../proj.tmsource, I'm going to know that something is wrong, and I would expect it to behave strangely.

I would say -- let's always resolve relative paths, and leave it up to the user to configure their project properly.