Parsing json in terraform locals - json

Question

I have another question about JSON parsing. Imagine I have this JSON:
{
"all_dogs" :[
{
"name": "foo",
"groups": ["morning", "evening"]
},
{
"name": "bar",
"groups": ["evening", "saturday"]
},
{
"name": "feet",
"groups": ["afternoon"]
}
]
}
I can extract all the groups like this:
locals {
all_dogs = jsondecode(file("${path.module}/dogs.json"))
all_groups = toset(flatten(local.all_dogs.all_dogs[*].groups))
}
Now, I’m trying to create a MAP. Each group is a key of the map and values of the maps are the different dogs in that group.
So I would like to create a map like this:
afternoon = [feet]
evening= [foo, bar]
morning= [foo]
saturday= [bar]
I'm trying with something like this and I tried several options... But I can't make it work.
output "ex" {
value = flatten([
for group in local.all_groups: [
for dog in local.all_dogs : {
group = group
dog = dog
}
]
]
)
}
Later on, I would like to use that map to provision some resources. Is this eventually possible?

Answer 1

locals {
all_dogs = jsondecode(file("${path.module}/dogs.json"))
groups = flatten([for d in local.all_dogs.all_dogs : [for g in d.groups : { key : g, value : d.name }]])
}
The value for local groups will be a list of tuples and it will look something like this:
groups = [
{
"key" = "morning"
"value" = "foo"
},
{
"key" = "evening"
"value" = "foo"
},
{
"key" = "evening"
"value" = "bar"
},
{
"key" = "saturday"
"value" = "bar"
},
{
"key" = "afternoon"
"value" = "feet"
},
]
Now we have to create a map from this list:
output "my_map" {
value = {
for g in local.groups : g.key => g.value...
}
}
This will produce the following output:
my_map= {
"afternoon" = [
"feet",
]
"evening" = [
"foo",
"bar",
]
"morning" = [
"foo",
]
"saturday" = [
"bar",
]