What is the correct way of using secrets in strategy-matrix pattern in GitHub Actions? - continuous-integration

Question

I am using GitHub Actions for one of the projects. I have a use case when I need to deploy to 2 different environments. As the number of domains may grow, I want to deploy to all of them at once parametrically.
Part of my job that fails:
jobs:
build:
strategy:
matrix:
domain: [['main', 'books-v1'], ['old-main', 'books-v2']]
The above part works perfectly but if I need to add new variants from the secrets, the workflow doesn't work. See the snippet below:
jobs:
build:
strategy:
matrix:
domain: [['main', 'books-v1', ${{ secrets.URL_V1 }}], ['old-main', 'books-v2', ${{ secrets.URL_V2 }}]]
I checked GitHub Actions docs. I also searched available examples on GitHub to see existing solutions. So far, I didn't find a similar use case.
Is there a way to make it work like that? What are alternatives to my approach that will work?
GitHub Actions failure message:
You have an error in your yaml syntax on line XYZ

Answer 1

At the YAML level, single quotes around ${{ secrets... }} should fix the syntax error.
But, according to the Context availability, the secrets context is not allowed under stratey. The allowed contexts are:
jobs.<job_id>.strategy github, needs, vars, inputs
You can make use of the vars context for your use case.
Apart from that, linting your workflow with https://rhysd.github.io/actionlint/ would be much faster to identify potential issues.
UPDATE (by Dmytro Chasovskyi)
Here is an example with the vars context:
With a variable DOMAINS having this config:
{
"v1": {
"url": "http://localhost:80/api/v1"
},
"v2": {
"url": "http://localhost:80/api/v2"
}
}
the workflow will be:
jobs:
build:
strategy:
matrix:
domain: [['main', 'books-v1', '${{ vars.DOMAINS.v1.url }}'], ['old-main', 'books-v2', '${{ vars.DOMAINS.v2.url }}']]