yq — jq for YAML, JSON, XML, TOML, and .properties

What it is

yq (Mike Farah's Go version) brings jq's query and transformation language to YAML, JSON, XML, TOML, .properties, and CSV files. If you have ever needed to patch a Kubernetes manifest, extract a value from a Helm chart, or merge configuration files in a CI pipeline, yq handles it with a familiar jq-compatible syntax.

DevOps engineers, SREs, and platform teams use yq anywhere YAML is involved -- which in the Kubernetes ecosystem means nearly everywhere. It is a single Go binary with no runtime dependencies.

How it saves time or tokens

yq replaces fragile sed/awk/grep pipelines for editing structured data. Instead of writing regex patterns that break when indentation changes, you use path expressions that understand YAML structure. The command yq '.spec.replicas = 5' deployment.yaml is safer and more readable than the equivalent sed command.

For AI workflows, yq can pre-process configuration files before feeding them to an LLM, extracting only the relevant sections to reduce prompt token count.

How to use

1. Install yq:

brew install yq          # macOS
sudo snap install yq     # Linux

1. Query a YAML file:

yq '.spec.replicas' deployment.yaml

1. Update a value in place:

yq -i '.spec.replicas = 5' deployment.yaml

Example

Merging two YAML files and converting to JSON:

# Merge base config with environment overlay
yq ea '. as $item ireduce ({}; . * $item)' base.yaml prod.yaml

# Convert YAML to JSON
yq -o=json deployment.yaml

# Extract all container images from a K8s manifest
yq '.spec.template.spec.containers[].image' deployment.yaml

These one-liners replace multi-line scripts that would otherwise require Python or a custom parser.

Related on TokRepo

• DevOps Tools -- Infrastructure and deployment tools for Kubernetes workflows
• Automation Tools -- CI/CD pipeline tools that work with config management

Common pitfalls

• There are two popular tools both named yq. The Go version by Mike Farah (most popular) and the Python version by Andrey Kislyuk use different syntax. Ensure you install the Go version (mikefarah/yq) for jq-compatible expressions.
• Multi-document YAML files require the ea (evaluate all) command instead of plain e. Without it, yq only processes the first document.
• Comments are preserved by default, which is usually desirable. However, format conversion (YAML to JSON) strips comments since JSON does not support them.