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Linter for LookML

Project description

lookmlint

Lint your LookML.

Provides additional linting checks beyond what is built into the LookML Validator.

usage

From the CLI:

$ lookmlint lint ~/my-lookml-repo

Alternatively, specify which checks to run:

$ lookmlint lint ~/my-lookml-repo --checks label-issues,views-missing-primary-keys

For structured output, set the --json flag:

$ lookmlint lint ~/my-lookml-repo --json

configuration

lookmlint looks for a file named .lintconfig.yml in your lookML project repo.

Its contents can contain lists of abbreviations and/or acronyms you'd like to flag. More detail below.

sample .lintconfig.yml

abbreviations:
  - num
  - qty
acronyms:
  - aov
  - sms
  - sku
  - sla

installation

Requires python3.

$ pip install lookmlint

lookml-parser dependency

This project invokes and relies on outputs generated by the awesome lookml-parser tool, which parses a lookML repo and outputs the results as json.

Ensure this is installed to get lookmlint to work properly:

$ npm install -g lookml-parser

checks

label-issues

acronyms

LookML automatically converts snake case strings (e.g. unit_cost_usd) to title case (e.g. Unit Cost Usd), which looks funny when using acronyms. Leverages the list of acronyms defined in .lintconfig.yml.

Bad

dimension: unit_cost_usd {
    ...
}

Good

dimension: unit_cost_usd {
    label: "Unit Cost (USD)"
    ...
}

abbreviations

If you'd prefer some words fully spelled out (e.g. 'Quantity' instead of 'Qty'), define a list of abbreviations for lookmlint to catch.

raw-sql-in-joins

Joins should refer to LookML dimensions as opposed to the underlying fields where possible.

For example:

Bad

join: order_items {
  sql_on: orders.id = order_items.order_id ;;
}

Good

join: order_items {
  sql_on: ${orders.id} = ${order_items.order_id} ;;
}

unused-includes

If your LookML model explicitly specifies views to include, lookmlint can catch views that are included in your model but not referenced in any of the explorations in that model.

unused-view-files

Find all view files that aren't referenced in any explorations in your project.

views-missing-primary-keys

Find all view files that don't contain a primary_key dimension.

duplicate-view-labels

Find any cases when two joins in an exploration end up with the same label.

One way this can unwittingly creep into code is if a label is defined in a view file, that view is joined twice to the same exploration, but view_labels are not assigned to those joins.

missing-view-sql-definitions

Find any views that do not have a sql_table_name or derived_table value set.

semicolons-in-derived-table-sql

Find any derived table SQL expressions that contain a rogue semicolon, which will throw errors at query time.

mismatched-view-names

Find any views where the view name does not match the view filename.

examples

The sample repo at examples/sample_repo/ contains instances of all linting violations:

~/src/lookmlint $$$ lookmlint lint examples/sample_repo/
Error:


duplicate-view-labels
---------------------
Model: test
  Explore: inventory_transfers
    Inventory Locations: 2


label-issues
------------
Fields:
  View: order_items
    - Qty: ['Qty']
    - Unit Cost Usd: ['USD']


mismatched-view-names
---------------------
- items.view.lkml: order_items


missing-view-sql-definitions
----------------------------
- order_items


raw-sql-in-joins
----------------
Model: test
  Explore: orders
    order_items: orders.id = order_items.order_id


semicolons-in-derived-table-sql
-------------------------------
- products


unused-includes
---------------
Model: test
  - web_sessions


unused-view-files
-----------------
- legacy_products
- web_sessions


views-missing-primary-keys
--------------------------
- order_items

adding to CircleCI

We use CircleCI at Warby Parker to run our checks.

Adding the following contents to .circleci/config.yml in your LookML project should work for running linting as part of your CI/CD workflow. This all runs in a few seconds, but leveraging caching could also help to speed things up.

Customize the list of checks you run to suit your team's needs, or leave out the --checks flag to run all possible lint checks.

version: 2
jobs:
  build:
    docker:
      - image: circleci/python:3.6.1
    working_directory: ~/repo
    steps:
      - checkout
      - run:
          name: Install lookml-parser
          command: |
            curl -sL https://deb.nodesource.com/setup_8.x | sudo -E bash -
            sudo apt install nodejs
            sudo npm install -g lookml-parser
      - run:
          name: Install lookmlint
          command: |
            sudo pip install lookmlint
      - run:
          name: Lint lookml
          command: |
            lookmlint lint . --checks label-issues,unused-includes,unused-view-files,mismatched-view-names,semicolons-in-derived-table-sql,missing-view-sql-definitions

issues?

This repo is still in alpha, so use at your own risk!

Please open an issue for any feature suggestions or bugs, or feel free to open a PR with a fix / feature!

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