Node scripts resetting ENV variables between script commands

Question

I'm trying to set NODE_EXTRA_CA_CERTS in a node script like so:

// package.json
"scripts": {
    "load-cert": "export NODE_EXTRA_CA_CERTS=cert.pem",
    "start": "node main.js"
  },

npm run load-cert && npm run start

But that doesn't work (gives SSL error). Specifically, I think, because I'm loading the contract in its own separate script then running a different script/command.

This also doesn't work

"scripts": {
    "load-cert": "export NODE_EXTRA_CA_CERTS=riotgames.pem",
    "start": "npm run load-cert && node main.js"
  },

npm run start

The following script works:

"scripts": {
    "start": "export NODE_EXTRA_CA_CERTS=cert.pem && node main.js"
  },

npm run start

Weirdly enough, this also works:

"scripts": {
    "start": "node main.js",
    "load-cert-start": "export NODE_EXTRA_CA_CERTS=riotgames.pem && npm run start"
  },

npm run load-cert-start

Can anyone help me understand why this is happening and if there's a way I can have a script to just load the certificate?

It's rather about bash than npm or node
– Konrad
Commented Sep 29, 2022 at 20:49 — Konrad, Commented Sep 29, 2022 at 20:49
I appreciate you adding the tag :)
– Brother58697
Commented Sep 29, 2022 at 21:17 — Brother58697, Commented Sep 29, 2022 at 21:17

Dark Falcon · Accepted Answer · 2022-09-30 17:40:25Z

2

Setting an environment variable with export sets it for the current process and all child processes, but NOT the parent process. When you run npm run load-cert, that is a new child process of your shell. When you run npm run start, that is a different child process of your shell and is not a child process of the shell that exported the variable.

* Your shell
  \ * npm run load-cert {}
    \ * shell {NODE_EXTRA_CA_CERTS=riotgames.pem}
  \ * npm run load-cert {}

If you combine the two commands together, as in export NODE_EXTRA_CA_CERTS=cert.pem && node main.js, then the node process is a child process of the shell with the environment variable set:

* Your shell
  \ * npm run load-cert {}
    \ * shell {NODE_EXTRA_CA_CERTS=riotgames.pem}
      \ * node {NODE_EXTRA_CA_CERTS=riotgames.pem}

Or export NODE_EXTRA_CA_CERTS=riotgames.pem && npm run start

* Your shell
  \ * npm run load-cert {}
    \ * shell {NODE_EXTRA_CA_CERTS=riotgames.pem}
      \ * npm run start {NODE_EXTRA_CA_CERTS=riotgames.pem}
        \ * node {NODE_EXTRA_CA_CERTS=riotgames.pem}

And for npm run load-cert && node main.js

* Your shell
  \ * npm run start {}
    \ * shell started by npm
      \ * npm run load-cert {}
        \ * shell {NODE_EXTRA_CA_CERTS=riotgames.pem}
      \ * node {} <-- Sibling, not child, of npm run load-cert

(Note I omitted a couple of non-relevant processes in-between in these diagrams)

edited Sep 30, 2022 at 17:40

answered Sep 29, 2022 at 20:52

Dark Falcon

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Thank you so much! If I understand you fully, run is the main culprit, spawning new processes with npm run load-cert && npm run start. But what I don't get, is why the second non-working example is spawning two processes, while the second working example is spawning child processes, even though they both run once.
– Brother58697
Commented Sep 29, 2022 at 21:06
1

@Brother58697, Added that case to the examples.
– Dark Falcon
Commented Sep 30, 2022 at 13:29
In the last example, shouldn't node {} be on the same level of shell {NODE_EXTRA_CA_CERTS=riotgames.pem}, as in they're siblings? Since node runs after load-cert so it becomes its child, but load-cert exports the variable in another child process.
– Brother58697
Commented Sep 30, 2022 at 15:00
1

No. npm run load-cert does not start node. Both are started by a shell started by npm run start (previously not shown in the diagram). The && is implemented by the shell. Also, running after does not mean it "becomes" its child.
– Dark Falcon
Commented Sep 30, 2022 at 17:39
1

Generally speaking, every process has an environment block in the kernel. This block stores all environment variables. export just modifies the values in this block. It is not a process, but a shell built-in command (handled by the shell itself). Whenever a new process is created, it receives a copy of the environment block of the process that created it. Obviously then, changes to the copy do not affect the original. A process uses the same environment block for its entire lifetime.
– Dark Falcon
Commented Sep 30, 2022 at 22:04

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