Set npm_config_user_agent when running scripts

[redabacha]

this is an env var that many scripts use to detect the package manager that ran the script. all major package managers including bun set this env var and it would be great if deno did too.

[lucacasonato]

All of these:

npm_config_global_prefix=/opt/homebrew
npm_config_noproxy=
npm_config_local_prefix=/Users/lucacasonato/projects/local/test
npm_config_globalconfig=/opt/homebrew/etc/npmrc
npm_config_userconfig=/Users/lucacasonato/.npmrc
npm_config_init_module=/Users/lucacasonato/.npm-init.js
npm_config_npm_version=10.7.0
npm_config_node_gyp=/opt/homebrew/lib/node_modules/npm/node_modules/node-gyp/bin/node-gyp.js
npm_config_cache=/Users/lucacasonato/.npm
npm_lifecycle_script=env | grep 'npm_config_'
npm_config_user_agent=npm/10.7.0 node/v22.1.0 darwin arm64 workspaces/false
npm_config_prefix=/opt/homebrew

[benmccann]

This environment variable is used by numerous CLIs to detect which package manager to run to install a package. E.g. Svelte uses it when creating a new project or adding integrations to an existing project

https://www.npmjs.com/package/which-pm-runs and https://www.npmjs.com/package/package-manager-detector are two highly used packages, which make use of this

[bartlomieju]

@benmccann thanks for pointing this out. Would it be okay if we only supported npm_config_user_agent env var to be able to figure out that you're currently running in Deno? If so would value like Deno/v2.x.y be enough?

[benmccann]

That would be enough for package-manager-detector used by Svelte, but would break the which-pm-runs library used elsewhere, which expects there to be at least one space: https://github.com/zkochan/packages/blob/221d0b81da4ecaa3489edbc158376fec52ca75eb/which-pm-runs/index.js#L11

to be safe I'd probably print something like:

deno/2.x.y npm/? deno/2.x.y

you can see examples of what other package managers do here: https://github.com/antfu-collective/package-manager-detector/blob/d8655170eae1c786de4eda1854af16480575fbb6/test/user-agent.spec.ts#L9

[redabacha]

yep it should be in the same style of format as how npm defines it, https://github.com/npm/cli/blob/f75da94f3bed6c0b637044e88098ec354cf302b0/workspaces/config/lib/definitions/definitions.js#L2107-L2126. e.g. with bun i get bun/1.1.30 npm/? node/v22.6.0 darwin arm64. deno already provides the node compat version in process.versions.node so could just use that here as well.

[bartlomieju]

Thanks for replies, @dsherret suggests that this should only be set for subprocesses spawned with node:child_process APIs. If that's the case it should be an easy fix and we can try to get it out in 2.0.1 tomorrow/Thursday.

[lucacasonato]

@bartlomieju i think this should only be set for deno task script execution

[redabacha]

well it should also be set for any kind of script you're running that's not a local one, i.e. deno -A npm:create-next-app should be setting the env var but running deno --allow-env ./main.ts shouldn't (well that's what bun is currently doing at least as the only other runtime+pm - but with that said i don't see any harm if that was to be included there too though :man_shrugging:).