Demo code for Pylint plugins integration in a Pants-managed repository

This demo comes along this Medium post about enabling Pylint 1st-party plugins in a repository managed by Pants.

More info:

• about Pants
• about Pylint 1st-party plugins

Quick Setup

Install dependencies:

./pants export ::

This creates several virtual environments. Among them, you'll find:

• pylint_plugins → the virtual env for custom pylint plugins (1st-party plugins)
• python-default → the virtual env for the runtime code
• tools/pylint → the virtual env for tools, in particular pylint here, which includes our 1st-party plugins and 3rd-party plugins)

Lint with 1st-party pylint plugin enabled

We have set an arbitrary linter rule that says: every prefect task definition name should be suffixed with "_task". In order to check that the 1st-party pylint plugin is working as expected, a code sample has been added to project/flows/example/tasks/dummy.py. This code sample is not valid regarding the rule defined in the pylint plugin.

You can now run the linter:

./pants lint ::

and you will get an error C9002 (invalid-task-definition-name) as expected.

An overview of how 1st-party plugins work

Ultimately, what you're looking for is that you can run your custom linter rules on your runtime code, and this can be illustrated with this:

flowchart TB
    subgraph repository-code [Repository code / projects / sources]
        direction TB
        R11["/"] -->|can be developed in| R12(ENV: resolve python-default)
        R21["/pylint_plugins"] -->|can be developed in| R22(ENV: resolve pylint-plugins)
    end
    
    subgraph pylint-ecosystem [Pylint Ecosystem]
        direction TB
        B[pylint_runner.pex] --> A["./pants lint"]
        C1[Pylint] --> B
        C2[3rd-party dependencies] --> B
        C3[1st-party plugins] --> B
        B --> B2(TOOL ENV: pylint)
    end
    
    A -->|runs lint on| R11["/"]
    R21 --> C3
    
    classDef command fill:#00b894,stroke:#2c3e50,text:#8e44ad;
    class A command
    
    classDef env fill:#3c40c6,stroke:#2c3e50,text:#8e44ad;
    class R12,R22 env
    
    classDef source fill:#4b6584,stroke:#2c3e50,text:#8e44ad;
    class repository-code source
    
    classDef tool fill:#485460,stroke:#2c3e50,text:#8e44ad;
    class pylint-ecosystem tool

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Troubleshoot

This sample is an illustration, and might contain issues, bugs and typos. If you find any, please report it.

For Apple Silicon machines (M1 & M2), you'll need to install openssl & libpq. Then prefix the export command with LDFLAGS="-L$(brew --prefix openssl)/lib" CPPFLAGS="-I$(brew --prefix openssl)/include"