(charmcraft-analyzers-and-linters)=

# Analysers and linters

The following are the different checks that Charmcraft will run explicitly (when the user executes its `analyse` method) or implicitly (when packing charms). 

Any linter or analysis can be set in [the config](https://juju.is/docs/sdk/charmcraft-config) to be excluded from the normal execution. Also note that if any linter ends in error it will block the charm packing (you can pack it anyway using  the `--force` option). 

You can read more about these checks in the [Charmcraft Analyze Specification](https://discourse.charmhub.io/t/proposal-charmcraft-analyze/4792).


## Language attribute

If through analysis, the charm can be detected as being a Python based charm, then language shall be set to `python`. If not, it shall be set to `unknown`.

When working with Python, it is possible to only publish byte-code. By doing so, troubleshooting is a harder task. Charms with Python sources delivered are preferred.

This attribute meets the requirements to be set to `python` when:

- the charm has a text dispatch which executes a .py
- the charm has a .py entry point
- the entry point file is executable

## Framework attribute


When using `ops`, it is best to import it from a common path and not make customisation or package forks from it. If `ops` code is detected in the charm sources, this attribute's value shall be set to `operator`. If not, the charm may be using the Reactive Framework, and in this case the attribute value will be `reactive`. Else, it shall be set to `unknown`.

This check hint meets the requirements for `ops` when:

- language attribute is set to `python`
- the charm contains `venv/ops`
- the charm imports `ops` in the entry point

The requirements for the Reactive Framework are:

...or the Reactive Framework is used, if the charm...

- has a metadata.yaml with `name` in it
- has a `reactive/<name>.py` file that imports `charms.reactive`
- has a file name that starts with `charms.reactive-` inside the `wheelhouse` directory


## Juju metadata linter

This linter verifies that the `metadata.yaml` file exists and is sane.

The charm is considered to have a valid metadata if the following checks are true:

- the `metadata.yaml` is present
- it is a valid YAML file
- it has at least the following fields: `name`, `summary`, and `description`


## Juju actions linter

*(new in 1.4)*

This linter verifies that the `actions.yaml` file, if exists, is a valid YAML file. The file is optional. The file contents are not verified.


## Juju config linter

*(new in 1.4)*

This linter verifies that the `config.yaml` file, if exists, is valid. This file is optional.

If the file exists, it is considered valid if the following checks are true:

- it has the `options` key
- it is a dictionary
- each item inside has the mandatory `type` key

Check how to [create config.yaml and configure charms](https://discourse.charmhub.io/t/creating-config-yaml-and-configuring-charms/1039) for more information.


## Charm entrypoint linter

*(new in 2.1)*

Check the entry point is correct. Note that even if most modern charms has a typical `src/charm.py` entry point, not all charms have one, as Juju has different ways to deliver its events.

This linter validates that, if an entry point is called from the `dispatch` file, that entry point...

- exists
- is a file
- is executable

The entry point content is *not* validated.