|author||Marcel van Lohuizen <email@example.com>||Mon May 13 10:59:45 2019 +0200|
|committer||Marcel van Lohuizen <firstname.lastname@example.org>||Thu May 16 17:30:37 2019 +0000|
cue/ast: allow CommentGroup as declaration This simplifies the construction of ASTs with free-floating comments. Also consecutive comment groups are now always printed with a newline in between. To not do so, one will have to merge two consecutive comment groups manually. This more closely matches the typical intention of comment groups. Change-Id: Id4a601bd6d255aa6c6489f43df52534ac5303af9 Reviewed-on: https://cue-review.googlesource.com/c/cue/+/2000 Reviewed-by: Marcel van Lohuizen <email@example.com>
Configure, Unify, Execute
CUE is an open source data constraint language which aims to simplify tasks involving defining and using data.
It is a superset of JSON, allowing users familiar with JSON to get started quickly.
You can use CUE to
CUE merges the notion of schema and data. The same CUE defintion can simultaneously be used for validating data and act as a template to reduce boilerplate. Schema definition is enriched with fine-grained value definitions and default values. At the same time, data can be simplified by removing values implied by such detailed definitions. The merging of these two concepts enables many tasks to be handled in a principled way.
Constraints provide a simple and well-defined, yet powerful, alternative to inheritance, a common source of complexity with configuration languages.
The CUE scripting layer defines declarative scripting, expressed in CUE, on top of data. This solves three problems: working around the closedness of CUE definitions (we say CUE is hermetic), providing an easy way to share common scripts and workflows for using data, and giving CUE the knowledge of how data is used to optimize validation.
There are many tools that interpret data or use a specialized language for a specific domain (Kustomize, Ksonnet). This solves dealing with data on one level, but the problem it solves may repeat itself at a higher level when integrating other systems in a workflow. CUE scripting is generic and allows users to define any workflow.
CUE is designed for automation. Some aspects of this are:
If you already have Go installed, the short version is:
go get -u cuelang.org/go/cmd/cue
This will install the
cue command line tool.
For more details see Installing CUE.
The fastest way to learn the basics is to follow the tutorial on basic language constructs.
A more elaborate tutorial demonstrating of how to convert and restructure an existing set of Kubernetes configurations is available in written form.
Language Specification: official CUE Language specification.
API: the API on godoc.org
Builtin packages: builtins available from CUE programs
cue Command line reference: the
Our canonical Git repository is located at https://cue.googlesource.com.
To contribute, please read the Contribution Guide.
To report issues or make a feature request, use the issue tracker.
Unless otherwise noted, the CUE source files are distributed under the Apache 2.0 license found in the LICENSE file.
This is not an officially supported Google product.