yaml.bzl

A pure Starlark YAML parser/serializer for Bazel.

Features

• Parse YAML into native Starlark values (dict, list, scalars)
• Multi-document support (--- / ...)
• Block and flow styles
• Block scalars (| / >) including chomping indicators
• Anchors, aliases, and mapping merge key (<<)
• Round-trip friendly serializer
• Error collection with optional strict mode

Installation

With bzlmod

bazel_dep(name = "yaml.bzl", version = "<version>")

With WORKSPACE

load("@bazel_tools//tools/build_defs/repo:http.bzl", "http_archive")

http_archive(
    name = "yaml.bzl",
    sha256 = "<sha256>",
    strip_prefix = "yaml.bzl-<version>",
    url = "https://github.com/scottpledger/yaml.bzl/releases/download/v<version>/yaml.bzl-v<version>.tar.gz",
)

Usage

load("@yaml.bzl//:yaml.bzl", "yaml")

doc = yaml.parse("""
service:
  name: demo
  ports: [8080, 8443]
""")

data = yaml.get_value(doc)
print(data["service"]["name"])  # demo

out = yaml.dump(data, sort_keys = True)
print(out)

API

Load:

load("@yaml.bzl//:yaml.bzl", "yaml")

Available members on yaml:

• parse(yaml_string, strict = False) -> document
• parse_all(yaml_string, strict = False) -> [document]
• dump(value, indent = 0, indent_str = " ", explicit_start = False, explicit_end = False, sort_keys = False, flow_style = False, yaml_version = None, tag_directives = None) -> string
• dump_all(values, indent = 0, indent_str = " ", explicit_start = True, explicit_end = False, sort_keys = False, flow_style = False, yaml_version = None, tag_directives = None) -> string
• validate_dump_directives(yaml_version, tag_directives) -> [string] (empty if dump/dump_all would accept those arguments)
• tag(tag, value) -> tagged_node
• anchor(name, value) -> anchored_node
• alias(name) -> alias_node
• get_value(document) -> any
• has_errors(document) -> bool
• get_errors(document) -> [error]
• is_document(node) -> bool
• is_mapping(value) -> bool
• is_sequence(value) -> bool
• is_scalar(value) -> bool

Error constants:

• yaml.ERROR_SYNTAX
• yaml.ERROR_INDENTATION
• yaml.ERROR_UNKNOWN_ALIAS