Serverless YML toUpperCase - yaml

Question

I want to reuse my serverless.yml in different environments (dev, test, prod).
In the config I have:
provider:
name: aws
stage: ${opt:stage, 'dev'}
environment:
NODE_ENV: ${self:provider.stage}
Right now the value will be dev, test or prod (all in lower-case).
Is there a way to convert it toUpperCase() in a way that the input and self:provider:stage will stay as it is (i.e. lower-case) but the value of NODE_ENV will be UPPER-CASE?

Answer 1

Update (2022-10-13)
This answer was correct at the time of its writing (circa 2018). A better answer now is to use serverless-plugin-utils as stated in #ShashankRaj's comment below.
varName: ${upper(value)}
AFAIK, there is no such function in YAML.
You can achieve what you want though by using a map between the lowercase and uppercase names.
custom:
environments:
dev: DEV
test: TEST
prod: PROD
provider:
name: aws
stage: ${opt:stage, 'dev'}
environment:
NODE_ENV: ${self:custom.environments.${self:provider.stage}}

Answer 2

You can achieve something to this effect using the reference variables in javascript files functionality provided.
To take your example, this should work (assuming you're running in a node.js environment that supports modern syntax)
serverless.yml
...
provider:
name: aws
stage: ${opt:stage, 'dev'}
environment:
NODE_ENV: ${file(./yml-helpers.js):provider.stage.uppercase}
...
yml-helpers.js (adjacent to serverless.yml)
module.exports.provider = serverless => {
// The `serverless` argument containers all the information in the .yml file
const provider = serverless.service.provider;
return Object.entries(provider).reduce(
(accumulator, [key, value]) => ({
...accumulator,
[key]:
typeof value === 'string'
? {
lowercase: value.toLowerCase(),
uppercase: value.toUpperCase()
}
: value
}),
{}
)
};

Answer 3

I arrived at something that works, via reading some source code and console logging the entire serverless object. This example applies a helper function to title-case some input option values (apply str.toUpperCase() instead, as required). There is a result of parsing the input options already available in the serverless object.
// serverless-helpers.js
function toTitleCase(word) {
console.log("input word: " + word);
let lower = word.toLowerCase();
let title = lower.replace(lower[0], lower[0].toUpperCase());
console.log("output word: " + title);
return title;
}
module.exports.dynamic = function(serverless) {
// The `serverless` argument contains all the information in
// the serverless.yaml file
// serverless.cli.consoleLog('Use Serverless config and methods as well!');
// this is useful for discovery of what is available:
// serverless.cli.consoleLog(serverless);
const input_options = serverless.processedInput.options;
return {
part1Title: toTitleCase(input_options.part1),
part2Title: toTitleCase(input_options.part2)
};
};
# serverless.yaml snippet
custom:
part1: ${opt:part1}
part2: ${opt:part2}
dynamicOpts: ${file(./serverless-helpers.js):dynamic}
combined: prefix${self:custom.dynamicOpts.part1Title}${self:custom.dynamicOpts.part2Title}Suffix
This simple example assumes the input options are --part1={value} and --part2={value}, but the generalization is to traverse the properties of serverless.processedInput.options and apply any custom helpers to those values.

Answer 4

Using Serverless Plugin Utils:
plugins:
- serverless-plugin-utils
provider:
name: aws
stage: ${opt:stage, 'dev'}
environment:
NODE_ENV: ${upper(${self:provider.stage})}
Thanks to #ShashankRaj...