| commit | bfdc42340876a79da5eb52477cfb04f5e096968c | [log] [tgz] |
|---|---|---|
| author | Grant Zvolsky <grant@zvolsky.org> | Sun Feb 09 20:13:05 2020 +0100 |
| committer | Marcel van Lohuizen <mpvl@golang.org> | Mon Feb 17 19:21:42 2020 +0000 |
| tree | 284797c9690bb17dfdaa476d8bb4636a02659aca | |
| parent | 0846b9324399ff782fcc38e0c156f418910b361c [diff] |
cmd/cue/cmd: prevent infinite loops while building dependency graph The existing implementatin resulted in an infinite loop in two cases: 1. In the v.Equals(after) call when the 'after' dependencies were cyclic 2. In the task.Walk function when task fields cyclically referenced other tasks This commit solves both cases by - stepping out of the Walk lambda when it had already been evaluated with the given parameter; and - removing the special case for 'after' dependencies as it is no longer necessary. Relevent tests are included. Updates #245 Change-Id: I914ff9aad96eb43ae89964000dea60ccd44c38a2 Reviewed-on: https://cue-review.googlesource.com/c/cue/+/4910 Reviewed-by: Marcel van Lohuizen <mpvl@golang.org>
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 definition 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:
Using Homebrew, you can install using the CUE Homebrew tap:
brew install cuelang/tap/cue
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 cue command
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.
Changes can be contributed using Gerrit or Github pull requests.
You can get in touch with the cuelang community in the following ways:
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.