HCL Map Reduce Support

[mariux]

We are proud to announce our newest addition to Variables:

The map {} block.

The map {} block is available in globals {} and lets {}.

Detailed docs and examples of the current state are available here.

The Problem

Terraform and HCL in general conflict with error when generating maps using { for ... : key => value } syntax that have duplicate keys.

In some complex scenarios this is blocking addition of features and there is no easy solution to it. Even if you as a developer have an idea about the resolution of duplicate keys, you are not able to implement it in pure HCL.

Some possible resolution of conflicts are:

• Replace: Take the last value in the list, overwriting previous values.
• Ignore: Take the first value in the list, ignoring any later values.
• Add: Create a combined value of all values in the list.
• Merge: Merge previous values applying any of the above strategies on each attribute.
• DeepMerge: Have different strategies for each attribute of nested maps.

Solution

The map {} block feature in Globals and Lets variable definitions allows to define a set of resolutions by allowing access to the current state of the map in each iteration.

This enables you to build a non conflicting complex and nested map from any input data.

Availability

We just released Terramate v0.2.7 over Christmas 2022.
This version has support for map inside of globals and lets blocks.

Please read detailed docs and feel free to give constructive feedback, raise issues, or ask questions in our GitHub discussions.

How we use it

We are currently refactoring our commercial products like the "Google Cloud Framework" that combines a Google Cloud Landing Zone and Google Cloud Service Catalogs for Compute, Big Data, and Machine Learning and AI workloads in a fully automated and easy to configure way.

The map {} feature allows us to provide even easier configuration options with less constraints in usage to our customers.