Hello, I am migrating to v1 and moving from

js

stacks to

ts

when set a function env variable to a process env var, I am getting this type safety error:

Type 'string | undefined' is not assignable to type 'string'.

I can put it like so:

environment: {
  var: process.env.var || ''
}

but In case I forgot to set an env var, I want it to be

undefined

and throw error in building time to notice it. So how can I get rid of this type of error?

you can try something like this,

// Throw error if client ID & secret are not provided
  if (!process.env.GOOGLE_CLIENT_ID || !process.env.GOOGLE_CLIENT_SECRET)
    throw new Error("Please set GOOGLE_CLIENT_ID and GOOGLE_CLIENT_SECRET");

Thanks @manitej, I have a lot of variables so I am trying to find more clear way

Alternatively you could define a

process.d.ts

file with the values that you expect. e.g.

declare namespace NodeJS {
  export interface ProcessEnv {
    GOOGLE_CLIENT_ID: string; // assert always present
    SOMETHING_ELSE?: string; // optional - need to check in code
  }
}

You can assert by doing

process.env.THING!

Thank you @Ross Coundon @thdxr for your nice solutions. I think if I used assertion with

!

, sst will throw an error in building time if the variable is

undefined

and I think that's enough for me now 😁

Another simple solution that I use quite often is to have a function like:

function ensureEnvVar(name: string) {
    const value = process.env[name];
    if(!value) throw new Error(`env var ${name} is missing`);
    return value;
}

then when you want to use an env var you do:

environment: {
  var: ensureEnvVar('MY_ENV_VAR')
}

yeah that's nice, thanks @Dan Coates

Another way…is to define a type predicate function that you can use to check the env var like this:

function isEnvVarSpecified(envVar: string): envVar is string {
  if (!envVar || typeof envVar !== 'string') {
    return false;
  }
  return true;
}