Skip to main content

Documentation Index

Fetch the complete documentation index at: https://mintlify.com/chainguard-dev/melange/llms.txt

Use this file to discover all available pages before exploring further.

melange query reads a melange YAML configuration file and evaluates a Go template expression against it, printing the result to stdout. This lets you extract any field from a package config — name, version, epoch, dependencies, or any other structured data — without writing a dedicated YAML parser. The output is plain text, making it easy to consume in shell scripts, CI pipelines, and automation tooling.

​
Usage

melange query <config.yaml> "<go-template>" [flags]
Both arguments are required. The template is evaluated against the top-level melange config structure, so fields are accessed via their Go struct paths (e.g. .Package.Name, .Package.Version).

​
Examples

# Print the full package version string (name-version-rEPOCH)
melange query crane.yaml "{{ .Package.Name }}-{{ .Package.Version }}-r{{ .Package.Epoch }}"
# Output: crane-0.19.1-r0

# Print just the version
melange query crane.yaml "{{ .Package.Version }}"
# Output: 0.19.1

# Print the package name
melange query crane.yaml "{{ .Package.Name }}"
# Output: crane

# Print the epoch
melange query crane.yaml "{{ .Package.Epoch }}"
# Output: 0

# Use in a shell script to tag a Docker image
VERSION=$(melange query crane.yaml "{{ .Package.Version }}")
docker tag crane:latest crane:${VERSION}

​
Template data model

The template receives the parsed melange config as its data object. Key top-level fields available in templates:
Template pathTypeDescription
.Package.NamestringPackage name
.Package.VersionstringPackage version
.Package.EpochintPackage epoch
.Package.DescriptionstringShort package description
.Package.Dependencies.Runtime[]stringRuntime dependencies
.EnvironmentstructBuild environment configuration
.Pipeline[]structBuild pipeline steps
.Subpackages[]structSubpackage definitions
The full data model mirrors the melange YAML schema. Any field that can appear in a melange YAML file can be accessed in a query template using Go template dot-notation.

​
Flags

melange query has no command-specific flags beyond the inherited global:
FlagDefaultDescription
--log-levelINFOLog verbosity: debug, info, warn, or error

​
Shorthand: package-version

For the common case of printing the full package version string, the melange package-version command provides a convenient shorthand: 
# Equivalent to: melange query config.yaml '{{ .Package.Name }}-{{ .Package.Version }}-r{{ .Package.Epoch }}'
melange package-version crane.yaml
# Output: crane-0.19.1-r0

​
CI script usage

melange query is particularly useful in CI/CD workflows where build steps need to read metadata from the package config: 
#!/usr/bin/env bash
set -euo pipefail

NAME=$(melange query mypackage.yaml "{{ .Package.Name }}")
VERSION=$(melange query mypackage.yaml "{{ .Package.Version }}")
EPOCH=$(melange query mypackage.yaml "{{ .Package.Epoch }}")

echo "Building ${NAME} ${VERSION} (epoch ${EPOCH})"

melange build mypackage.yaml \
  --signing-key local-melange.rsa \
  --arch x86_64,aarch64

# Upload to a GCS bucket named after the version
gsutil cp packages/x86_64/*.apk "gs://my-repo/${VERSION}/"
Go templates support the full range of template functions including printf, index, range, and if conditionals. For complex extractions, refer to the Go template documentation.

Build docs developers (and LLMs) love

Get started for freeTalk to us