Support for multiple tag variables

Oct 13, 2025 by wbrum.org 94 views

Introduction

CUE is a powerful tool for building and managing configuration files. One of its key features is the ability to inject variables into the command line. However, the current documentation does not provide clear guidance on how to pass in the current environment variables. In this article, we will explore the current state of CUE's tag injection variables and propose an addition to include the entire environment.

Current State of CUE's Tag Injection Variables

CUE's tag injection variables are a powerful feature that allows users to inject variables into the command line. These variables can be used to customize the behavior of CUE and make it more flexible. However, the current documentation does not provide clear guidance on how to pass in the current environment variables.

What is the Current Environment?

The current environment refers to the set of k=v environment variables for the process in which CUE is evaluating. These variables are set by the operating system and can be used to customize the behavior of CUE.

What is the Current Documentation?

The current documentation for CUE's tag injection variables can be found on the official CUE website. Specifically, the documentation can be found on the CUE Help Injection page.

What is Missing from the Current Documentation?

The current documentation does not provide clear guidance on how to pass in the current environment variables. While it is possible to link to an as-yet-not-created page about using -t with individual environment variables, it would be more helpful to offer a tag variable for the entire [string]: string environment.

Proposal: Add Environment to Tag Injection Variables

To address the current limitation, we propose adding a new tag variable that includes the entire environment. This would allow users to easily pass in the current environment variables and customize the behavior of CUE.

Benefits of the Proposal

The proposed addition would provide several benefits, including:

Improved flexibility: By allowing users to pass in the current environment variables, CUE would become more flexible and easier to use.
Simplified documentation: The addition of a new tag variable would simplify the documentation and make it easier for users to understand how to use CUE.
Increased adoption: By providing a more comprehensive set of features, CUE would become more attractive to users and increase its adoption.

Implementation

To implement the proposed addition, we would need to modify the CUE codebase to include a new tag variable that includes the entire environment. This would involve adding a new function to the CUE codebase that would retrieve the current environment variables and make them available as a tag variable.

Example Use Case

Here is an example use case that demonstrates how the proposed addition would work:

#cue -t env=GOOS=linux GOARCH=arm64

In this example, the -t flag is used to specify a tag variable named env. The value of the env variable is set to a string that includes the current environment variables, including GOOS and GOARCH.

Conclusion

In conclusion, the proposed addition of a new tag variable that includes the entire environment would provide several benefits, including improved flexibility, simplified documentation, and increased adoption. We believe that this addition would be a valuable feature for CUE users and would make the tool more attractive to a wider range of users.

Future Work

In the future, we would like to explore additional features that would make CUE even more powerful and flexible. Some potential areas of future work include:

Support for multiple tag variables: Currently, CUE only supports a single tag variable. In the future, we would like to add support for multiple tag variables, which would allow users to specify multiple variables at once.
Improved documentation: While the current documentation is a good starting point, we believe that it could be improved. In the future, we would like to add more examples, tutorials, and other resources to help users get started with CUE.
Integration with other tools: CUE is a powerful tool that can be used in a variety of contexts. In the future, we would like to explore integrating CUE with other tools and frameworks, such as Kubernetes and Docker.
cmd/cue: Add Environment to Tag Injection Variables - Q&A =====================================================

Introduction

In our previous article, we proposed adding a new tag variable to CUE that includes the entire environment. This feature would provide several benefits, including improved flexibility, simplified documentation, and increased adoption. In this article, we will answer some frequently asked questions about the proposed feature.

Q: What is the current state of CUE's tag injection variables?

A: CUE's tag injection variables are a powerful feature that allows users to inject variables into the command line. However, the current documentation does not provide clear guidance on how to pass in the current environment variables.

Q: What is the current documentation for CUE's tag injection variables?

A: The current documentation for CUE's tag injection variables can be found on the official CUE website. Specifically, the documentation can be found on the CUE Help Injection page.

Q: What is missing from the current documentation?

A: The current documentation does not provide clear guidance on how to pass in the current environment variables. While it is possible to link to an as-yet-not-created page about using -t with individual environment variables, it would be more helpful to offer a tag variable for the entire [string]: string environment.

Q: How would the proposed feature work?

A: The proposed feature would add a new tag variable that includes the entire environment. This would allow users to easily pass in the current environment variables and customize the behavior of CUE.

Q: What are the benefits of the proposed feature?

A: The proposed feature would provide several benefits, including:

Improved flexibility: By allowing users to pass in the current environment variables, CUE would become more flexible and easier to use.
Simplified documentation: The addition of a new tag variable would simplify the documentation and make it easier for users to understand how to use CUE.
Increased adoption: By providing a more comprehensive set of features, CUE would become more attractive to users and increase its adoption.

Q: How would the proposed feature be implemented?

A: To implement the proposed feature, we would need to modify the CUE codebase to include a new tag variable that includes the entire environment. This would involve adding a new function to the CUE codebase that would retrieve the current environment variables and make them available as a tag variable.

Q: What is an example use case for the proposed feature?

A: Here is an example use case that demonstrates how the proposed feature would work:

#cue -t env=GOOS=linux GOARCH=arm64

Q: What are the potential future developments for CUE?

A: In the future, we would like to explore additional features that would make CUE even more powerful and flexible. Some potential areas of future work include:

Support for multiple tag variables: Currently, CUE only supports a single tag variable. In the future, we would like to add support for multiple tag variables, which would allow users to specify multiple variables at once.
Improved documentation: While the current documentation is a good starting point, we believe that it could be improved. In the future, we would like to add more examples, tutorials, and other resources to help users get started with CUE.
Integration with other tools: CUE is a powerful tool that can be used in a variety of contexts. In the future, we would like to explore integrating CUE with other tools and frameworks, such as Kubernetes and Docker.

Conclusion

In conclusion, the proposed feature of adding a new tag variable that includes the entire environment would provide several benefits, including improved flexibility, simplified documentation, and increased adoption. We believe that this feature would be a valuable addition to CUE and would make the tool more attractive to a wider range of users.