Accessing the first object in a tuple using terraform - json

Question

I am trying to access the first key on a given tuple. The key's name is dynamic and may change so it cannot be accessed using a static value and has to be done either through a for loop or through the use of terraform fuctions.
I've created a small local resource that outputs the following section
skip_empty_mails = { for key, value in local.j.settings.tasks : key => value.email_notifications if value.email_notifications != {} }
The output sent back is
{
"3" = {
"on_start" = [
"foo1#aligntech.com",
"foo2#aligntech.com",
"foo3#aligntech.com",
"foo4#aligntech.com",
]
}
"4" = {
"no_alert_for_skipped_runs" = false
"on_start" = [
"foo21#aligntech.com",
"foo22#aligntech.com",
"foo23#aligntech.com",
"foo24#aligntech.com",
]
]
"on_start" = [
"foo21#aligntech.com",
"foo22#aligntech.com",
"foo23#aligntech.com",
"foo24#aligntech.com",
]
"on_success" = [
"foo21#aligntech.com",
"foo22#aligntech.com",
"foo23#aligntech.com",
"foo24#aligntech.com",
]
}
}
As seen above the key that holds all the values needs to be accessed in a way that will give me the ability to attach it to a string and use string.on_start to pull its values.
The issue is that our key's name is dynamic and may vary.
I've tried following the terraform function documentation But haven't found anything that might be of use in this case.
You may be able to replicate using the following code
locals {
json = {
"3" = {
"on_start" = [
"foo1#aligntech.com",
"foo2#aligntech.com",
"foo3#aligntech.com",
"foo4#aligntech.com",
]
},
"4" = {
"no_alert_for_skipped_runs" = false
"on_failure" = [
"foo21#aligntech.com",
"foo22#aligntech.com",
"foo23#aligntech.com",
"foo24#aligntech.com",
]
"on_start" = [
"foo21#aligntech.com",
"foo22#aligntech.com",
"foo23#aligntech.com",
"foo24#aligntech.com",
]
"on_success" = [
"foo1#foo.com",
"foo2#foo.com",
"foo3#foo.com",
"foo4#foo.com",
]
}
}
}

Answer 1

You can try with a combination of values, element or flatten see the documentation:
https://developer.hashicorp.com/terraform/language/functions/values
https://developer.hashicorp.com/terraform/language/functions/element
https://developer.hashicorp.com/terraform/language/functions/flatten
Below are samples:
First key extraction
locals {
json = {
"4" = {
"no_alert_for_skipped_runs" = false
"on_failure" = [
"foo1#foo.com",
"foo2#foo.com",
]
"on_start" = [
"foo1#foo.com",
"foo2#foo.com",
]
}
}
}
output "data" {
value = element(values(local.json), 1).on_start
}
the Terraform plan will be:
Changes to Outputs:
+ data = [
+ "foo1#foo.com",
+ "foo2#foo.com",
]
Extract and combine on_start item from all
locals {
json = {
"3" = {
"on_start" = [
"foo1#aligntech.com",
"foo2#aligntech.com",
]
},
"4" = {
"on_start" = [
"foo1#foo.com",
"foo2#foo.com",
]
}
}
}
output "data" {
value = flatten(values(local.json)[*].on_start)
}
the Terraform plan will be:
Changes to Outputs:
+ data = [
+ "foo1#aligntech.com",
+ "foo2#aligntech.com",
+ "foo1#foo.com",
+ "foo2#foo.com",
]