To expand upon previous answers, each map must be declared and instantiated (as well as the struct at the end of the map), that means you'll need to instantiate the "outer" map

mapOfMaps := make(map[string]map[string]myStruct)

as well as the "inner" map(s) for each key you have.

mapOfMaps[key] := make(map[string]myStruct)

The obvious issue you run into here is how do you dynamically check to see if the mapOfMaps[key] has already been instantiated? You do this using the following syntax:

if _, ok := mapOfMaps[key]; !ok {
    mapOfMaps[key] := make(map[string]myStruct)
}

This syntax checks to see if mapOfMaps already has an instantiated value for that key, and if not instantiates it. Similarly, you can use the same syntax to instantiate the structs you are using by checking to see of mapOfMaps[key][key2] has been instantiated yet.

if _, ok := mapOfMaps[key][key2]; !ok {
    mapOfMaps[key][key2] := new(myStruct)
}

Now you can access the struct through the call to 2 keys and an attribute of the struct

fmt.Println(mapOfMaps[key][key2].atrib1)

To expand upon previous answers, each map must be declared and instantiated (as well as the struct at the end of the map), that means you'll need to instantiate the "outer" map

mapOfMaps := make(map[string]map[string]myStruct)

as well as the "inner" map(s) for each key you have.

mapOfMaps[key] = make(map[string]myStruct)

The obvious issue you run into here is how do you dynamically check to see if the mapOfMaps[key] has already been instantiated? You do this using the following syntax:

if _, ok := mapOfMaps[key]; !ok {
    mapOfMaps[key] = make(map[string]myStruct)
}

This syntax checks to see if mapOfMaps already has an instantiated value for that key, and if not instantiates it. Similarly, you can use the same syntax to instantiate the structs you are using by checking to see of mapOfMaps[key][key2] has been instantiated yet.

if _, ok := mapOfMaps[key][key2]; !ok {
    mapOfMaps[key][key2] = new(myStruct)
}

Now you can access the struct through the call to 2 keys and an attribute of the struct

fmt.Println(mapOfMaps[key][key2].atrib1)