dy

Construct YAML from a directory tree

Description

The entire world seems to think declarative configuration is best represented as YAML. This is especially prevalent in the land of Kubernetes and related tools. Terrible ideas have a tendency to accumulate leading to awful solutions to the wrong problems.

Whilst this tool doesn't pretend to move the mountain it does try to nudge it back in the right direction.

Put simply, dy allows one to build a YAML document from a directory tree containing snippets of YAML. The aim is to make the document easier to reason about and maintain.

It is useful everywhere complex YAML configuration is employed: CI pipelines, Cloudformation, Kubernetes, etc. See the examples for inspiration, especially in tandem with envsubst.

Introducing Divvy Yaml

divvy /ˈdɪvi/ - To share out. Informal, British - A foolish or stupid person

dy parses a directory tree according to the following rules:

• A directory is a text key
• A file name has contents that are rendered under a key named after the file prefix
• A file name that begins with an underscore is rendered without a key at the current indentation level

Consider the following example:

$ tree k8s_deployment/
k8s_deployment/
├── _header.yaml
├── metadata.yaml
└── spec
    ├── _replicas.yaml
    ├── selector.yaml
    └── template
        ├── metadata
        │   └── labels.yaml
        └── spec
            └── containers.yaml

4 directories, 6 files

$ dy k8s_deployment/
apiVersion: apps/v1
kind: Deployment
metadata:
  name: nginx-deployment
  labels:
    app: nginx
spec:
  replicas: 3
  selector:
    matchLabels:
      app: nginx
  template:
    metadata:
      labels:
        app: nginx
    spec:
      containers:
        - name: nginx
          image: nginx:1.7.9
          ports:
          - containerPort: 80

$ dy k8s_deployment/ | kubectl apply --validate=true --dry-run=true -f -
deployment.apps/nginx-deployment created (dry run)

You may pass multiple directories as arguments and they will each be parsed and emitted as documents in their own right. In this way a single dy invocation can be used to produce a valid multi-document YAML stream.

Installing

Homebrew

brew tap sampointer/dy
brew install dy

Manually

Download the appropriate package for your distribution from the releases page.