how to add an additional loop over a stringlist within a for_each - for-loop

Question

i've setted up multiple github repos within my .tf configuration with a simple for_each on "github" repository resource. In addition i tried to create several branches (a branch per env) for each newly created repo.
My first intention was to use a module (./modules/github_repo/repo.tf) which includes
locals {
environments = var.environments
}
resource "github_branch" "branches" {
for_each = toset(setsubtract(local.environments, ["prod"]))
repository = "orgName/${var.REPO_NAME}"
branch = lookup(var.environment_to_branch_map, each.key, each.key)
source_branch = "master"
}
with following variables
variable "REPO_NAME" {
type = string
}
variable "environments" {
type = list(string)
}
variable "environment_to_branch_map" {
type = map(any)
default = {
"prod" = "master"
"dev" = "develop"
}
calling like this from main.tf
provider "github" {
token = var.GITHUB_TOKEN
owner = "orgName"
}
locals {
environments = ["dev", "prod", "staging", "test"]
microServices = tomap({ "service1" : "fnApp", "service2" : "fnApp" })
default_branch = "master"
}
module "branches_per_microservice" {
for_each = local.microServices
source = "./modules/github_repo"
REPO_NAME = each.key
environments = local.environments
depends_on = [github_repository.microservices]
}
unfortunately i get an 404 for each branch and repo combination like this
Error: Error querying GitHub branch reference /orgName/service1 (refs/heads/master): GET
https://api.github.com/repos//orgName/service1/git/ref/heads/master: 404 Not Found []
with
module.branches_per_microservice["service1"].github_branch.branches["test"]
on modules/github_repo/repo.tf line 23, in resource "github_branch" "branches":
i guess it's a "provider" thing, cause if i try to create a branch directly in the main.tf, it will work. but the problem is, that i only can use one loop within a resource. (i already know that providers are not possible in modules with count or for_each loops, as written in terraform docs)
resource "github_branch" "branches" {
for_each = toset(setsubtract(local.environments, ["prod"]))
repository = github_repository.microservices["service1"].name
branch = lookup(var.environment_to_branch_map, each.key, each.key)
source_branch = "master"
}
in this case, i have to create a resource for each "MicroService" manually, which i want to avoid heavily... Are there any ideas how i could "nest" the second loop over the environments to create my branches for each Micorservice repos?
Many thx in advance for any hint, idea or approach here...

Answer 1

Nested loop can be replaced with a single loop over the setproduct of two sets. The documentation for setproduct can be found here
https://www.terraform.io/language/functions/setproduct