Parameterize CLI script written in Deno

[quilicicf]

Hi guys,

I'm trying to do something that I'm not sure is supported in Deno and I am wondering if I missed a feature or if there is a possible improvement to Deno.

What

I'm trying to write a CLI tool that's supposed to have access to a single folder on the user's machine. The idea:

1. the whole configuration/assets live in a single folder (meaning, copy/pasting this folder replicates the whole behavior of the tool)
2. the tool can only read/write to that folder and no other
3. it asks for minimal permissions

So, for example, if a user wants to install my tool in /home/me/forge, I'd like them to be able to install it with deno install --allow-read=/home/me/forge AND I'd like my script to know where that folder is.

How

I have tried the options below:

• read the folders the tool is allowed to read at runtime => not possible (probably security reasons?)
• put the configuration (containing the folder path) in HOME => requires allow-env, breaks #1, two-step installation
• inject the project folder at installation => deno install currently can't do that, I'd have to write a wrapping installation script. Seems convoluted and does not inspire trust

From my perspective, this looks like a use-case others might run into and it would be nice to have it supported by Deno It would probably best be solved at installation (new capabilities in deno install?).

WDYT? Any solution I missed?

[harshagarwalnyu]

Careful, import.meta.url won't give you the install directory. When you deno install a script from a remote URL, the generated shim still points at that remote URL, so at runtime import.meta.url is something like https://.../mod.ts, not a local path. new URL(".", import.meta.url).pathname just gives you the remote path portion, and import.meta.filename / import.meta.dirname are only set for local file:// modules, so they're undefined for a remotely installed script.

For parameterizing the CLI, the runtime-native ways are:

1. Command-line args, simplest:

const [configPath] = Deno.args;
// deno run --allow-read mytool /path/to/config.json

2. An env var:

const dir = Deno.env.get("MYTOOL_HOME") ?? "";

3. A fixed config location derived from the home dir, e.g. Deno.env.get("HOME") + "/.config/mytool/", and scope your --allow-read / --allow-write to exactly that.

Any of those is stable regardless of where the tool is installed. The import.meta.url route only works when you run the script directly from a local file, not through deno install.