In deno tasks, automatically add $DENO_DIR/bin to PATH

[dz4k]

(Should this issue be in the deno_task_shell repo? Apologies if so.)

I am writing a Deno web app intended to be run by people who might not otherwise use Deno. I use Deno tasks for starting the server.

A user had downloaded Deno but hadn't added it to their PATH, and was trying to run the project with the command ~/.deno/bin/deno task run, which failed since the run task calls Deno recursively.

As far as I can tell, my tasks cannot predict where Deno will be downloaded, and (I assume?) calling Deno within tasks is a common use case.

I propose that the Deno installation directory be prepended to the PATH environment variable before running tasks. This will work for tasks, shell scripts and shebangs since they all will inherit the environment from the deno task process.

[dsherret]

A user had downloaded Deno but hadn't added it to their PATH, and was trying to run the project with the command ~/.deno/bin/deno task run, which failed since the run task calls Deno recursively.

That's strange. There's special logic to use the current executing version of deno for the deno command:

https://github.com/denoland/deno_task_shell/blob/250c0b7269bfaf2f9afc03abe4e3e0ae1b5fee8e/src/shell/commands/executable.rs#L110-L124

What was the error they saw? Are they using the latest version of Deno?

[dz4k]

Looking at the output more carefully, it seems like the failed execution is in a shebang.

$ ~/.deno/bin/deno task run
Task run deno task bundle-assets && bin/denizen.ts
Task bundle-assets deno run -A tool/assets_to_module.ts
/usr/bin/env: ‘deno’: No such file or directory

Modifying the environment instead of special-casing in the shell would make this work. On the other hand, I don't think that shebang will work on Windows anyway, and I should definitely change it.

[dz4k]

bin/denizen.ts:

#!/usr/bin/env -S deno run -A --unstable
import { app } from '../lib/denizen.ts'
Deno.serve({
	hostname: '0.0.0.0',
	port: Deno.env.has('PORT') ? Number(Deno.env.get('PORT')) : undefined,
}, app.fetch)

[dsherret]

It's a good point that it might be better to add the executing directory of deno to the shell path because then it would work when a sub process executes Deno too.

On the other hand, I don't think that shebang will work on Windows anyway, and I should definitely change it.

I can implement denoland/deno_task_shell#23 -- will try to do it tomorrow as I'd like to get that in the minor release on Thursday.