charmlint
A charm-aware, model-agnostic linter for Juju charms.
charmlint checks charm source code against Canonical's Juju charm best practices: observability (COS integration, ops-tracing), security (PEP 740 PyPI attestations), testing structure, metadata completeness, configuration quality, and more.
Extracted from tonyandrewmeyer/cantrip,
where charmlint grew as an internal component of the Cantrip AI charm builder.
Installation
uv sync --dev
Usage
uv run charmlint /path/to/charm
uv run charmlint --format json /path/to/charm
uv run charmlint --select COS,META /path/to/charm
uv run charmlint --ignore ATT002 --strict /path/to/charm
Or install and run directly:
uv run pip install -e .
charmlint /path/to/charm
Running tests
uv run pytest tests/ -v
Rule catalogue
Rule IDs follow CATEGORY-### (for example SECURITY-001,
METADATA-003). See docs/id-scheme.md for the full
category catalogue and naming rules.
Configuration
Configure under [tool.charmlint] in pyproject.toml, or in a standalone
charmlint.toml / .charmlint.toml. Discovery walks up from the charm
directory, in the manner of ruff.
[tool.charmlint]
severity = "warning" # minimum severity to report
select = ["OBSERVABILITY", "METADATA"]
ignore = ["ATTESTATION-002"]
[tool.charmlint.per-rule-severity]
"OBSERVABILITY-005" = "error"
Suppressing findings inline
Individual findings can be silenced from within a charm's YAML files with
ruff-style # noqa comments.
An inline # noqa suppresses every finding reported on that line; add a
comma-separated list of codes to suppress only those. A code is a full
rule ID (SECURITY-001) or a category (SECURITY):
config:
options:
admin-password: # noqa: SECURITY-001
type: string
A file-level # charmlint: noqa (on any line) suppresses the whole file;
# charmlint: noqa: SECURITY-001 suppresses only the listed rules across
the file:
# charmlint: noqa: SECURITY-001
Inline # noqa only applies to findings that carry a line number;
findings that anchor to a whole file are silenced with a file-level
directive instead. Only YAML files are scanned.
Versioning
charmlint follows a ruff-style versioning scheme: the minor version carries breaking changes (such as new or sharpened rules being enabled by default) and the patch version carries bug fixes. See docs/versioning.md for the full policy.
License
Apache 2.0 — see LICENSE.
1 maintainer
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File details
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The following attestation bundles were made for charmlint-0.1.1-py3-none-any.whl:
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