Conditional variables in aws-nodejs-typescript template

Serverless Framework
1

I’m having some issues with the TypeScript template, specifically this:

  provider: {
    name: 'aws',
    runtime: 'nodejs12.x',
    memorySize: 256,
    timeout: 10,
    // @ts-ignore
    logRetentionInDays: '${self:custom.logRetention.${self:provider.stage}}',

I want to have the value be 3 days for dev, and 30 days for prod. Of course, TypeScript yells at me for using a string here, even though it’s completely legit and works fine.

Is there a better way to do conditional variables? If only self:provider.stage was injected into process.env, that would be incredibly useful.

2

Well, it’s not completely legit, since it’s not supposed to be a string. Sure, Javascript will auto-convert it to a number in many cases, but I guess you’re using TypeScript because you want strong typing?

Anyway, simply convert it to an integer. You can use parseInt(), Number(), or simply put a plus in front:
logRetentionInDays: +’{self:custom.logRetention.{self:provider.stage}}’

Alternatively, if you feel it really SHOULD accept a string (I, for one, definitely do not), make a bug report on the serverless/typescript Github repo, asking for widening of the allowed types in the interface.

3

Hmmm… You’re actually right. The string will be replaced by the actual value, but the config doesn’t know that until it has converted the value, so a string should be accepted.

4

Aside from using @ts-ignore, this also works, though it looks ugly:

logRetentionInDays: Number('${self:custom.env.LOG_RETENTION_DAYS}') as AWS['provider']['logRetentionInDays']

The as 3 | 30 is necessary because the logRetentionDays is typed as:

logRetentionInDays?: 1 | 3 | 5 | 7 | 14 | 30 | 60 | 90 | 120 | 150 | 180 | 365 | 400 | 545 | 731 | 1827 | 3653;

EDIT: Nope, apparently my alternate solution doesn’t work. Once you use Number() on it, it returns null for some reason. Strange, because Number('3') definitely does not equal null.