tekton-lint

A linter for Tekton resource definitions

• tekton-lint
  • Quick Start
  • History
  • Usage - CLI
  • What yaml files to include?
  • Rules
    • Detecting errors
    • Best practices
  • Configuring tekton-lint
  • Custom Rules
    • Configuring
    • Reporting
  • Issues?

Quick Start

Make sure you've NodeJS v18 or later installed, and run....

npx @ibm/tekton-lint@latest <glob-pattern-to-yaml-files>

To try a quick example, grab the example-task.yaml from this repo

> wget https://raw.githubusercontent.com/IBM/tekton-lint/main/example-task.yaml
> npx @ibm/tekton-lint@latest  example-task.yaml

example-task.yaml
   4:9   error    Invalid name for Task 'Task-without-params'. Names should be in lowercase, alphanumeric, kebab-case format  no-invalid-name
  10:14  warning  Invalid image: 'busybox'. Specify the image tag instead of using ':latest'                                  no-latest-image
   9:31  error    Undefined param 'contextDir' at .spec.steps[0].command[2] in 'Task-without-params'                          no-undefined-param
  11:19  error    Undefined param 'contextDir' at .spec.steps[0].workingDir in 'Task-without-params'                          no-undefined-param

✖ 4 problems (3 errors, 1 warning)

You can use the tool as a regular lint tool from the CLI or scripts; alternatively you can use it as a library via it's API or from an IDE such as VScode. (please consider both the API and IDE use as experimental features.)

History

When I first started using Tekton a few years ago, I found one of the harder things was keeping track of the dependencies between the YAML files. Comparing to say github actions, or travis, Tekton is a lot more verbose. The comparison isn't quite fair as the tools do work at slightly different levels.

Nevertheless, I was pleased to find this TektonLint tool; it was able to spot a number of the 'gotchas' before pushing the pipelines for execution. After a brief hiatus, I was using Tekton again. Bence Dányi the original author was no longer at IBM; as the tool had been useful for me I decided to take on the repo.

I've updated typescript versions, added in additional features such as custom rules, allowed for caching of standard components. Theres more still I'd like to do; but of a MVP it's at v1.

Usage - CLI

tekton-lint is parsing the passed files as yaml files, and checks the rules on the resulting document set. [More details on the pattern syntax.][pattern]

Using tekton-lint in watch mode will monitor for any changes in the provided paths and automatically run the linter again.

Be mindful if you specify a glob pattern (eg *.yaml) that this might be expanded by your shell rather than the tool itself. It'll probably be fine for the vast majority of cases.

tekton-lint [<options>]  <glob-pattern-to-yaml-files> ...

Options:
  --watch           Run tekton-lint in watch mode     [boolean] [default: false]
  --color          Forcefully enable/disable colored output
                                                       [boolean] [default: true]
  --format         Format output. Available formatters: vscode | stylish | json
            [string] [choices: "vscode", "stylish", "json"] [default: "stylish"]
  --quiet          Report errors only                 [boolean] [default: false]
  --max-warnings   Number of warnings to trigger nonzero exit code
                                                          [number] [default: -1]
  --config         location of the .tektonlintrc.yaml, defaults to cwd
                                             [string] [default: "/home/matthew"]
  --refresh-cache  If true will delete the cache directory for external tasks
                                                    [boolean] [default: "false"]
  --version        Show version number                                 [boolean]
  --help           Show help                                           [boolean]

Examples:
  tekton-lint "**/*.yaml"                   Globstar matching
  tekton-lint path/to/my/pipeline.yaml      Multiple glob patterns
  "path/to/my/tasks/*.yaml"
  tekton-lint --watch "**/*.yaml"           Watch mode

What yaml files to include?

Only the yaml files that are specified are linted; these can be defined either on the command line, or via the .tektonlintrc.yaml file.

globs:
  - example*.yaml

If both command line and the configuration file have patterns specified, both are used but the command line options come first.

Depdending on how your Tekton instance is configured sometimes you might be using task descriptions that aren't part of your project or repository. In this case you'll get linter errors that "Task XYZ can't be found" - the latest v1 version of tool has added the concept of 'external tasks'.

For example if you are using some of the OpenToolchain Tasks, you can add the following to the configuration file

---
external-tasks:
  - name: git-clone-repo
    uri: https://github.com/open-toolchain/tekton-catalog
    path: git
  - name: toolchain-extract-value
    uri: https://github.com/open-toolchain/tekton-catalog
    path: toolchain
  - name: doi-publish-build-record
    uri: https://github.com/open-toolchain/tekton-catalog
    path: devops-insights    
  - name: icr-publish
    uri: https://github.com/open-toolchain/tekton-catalog
    path: container-registry
  - name: iks-detch
    uri: https://github.com/open-toolchain/tekton-catalog
    path: kubernetes-service

This will clone the repos specified and extract the various directories to a local cache. When you lint your tools these external tasks and definitions will be included. This will prevent any errors about tasks missing; but also importantly ensure your use of the tasks is correct, eg no missed parameters.

Note that these cached files won't be linted themselves.

The cache is defined to be put to ~/.tektonlint If you wish to clear the cache, simply delete this directory - alternatively there is a cli option.

Rules

Please note that the tool assumes that the files are syntax correct YAML files, and they are following the established schema for Tekton. For example referring to a field with the wrong spelling or case will confuse the rules.

If you see an error like Pipeline 'pipeline-test-perf-tag' references task 'undefined' but the referenced task cannot be found. referencing 'undefined' this more than likely means there is a syntax error in the yaml file. This can be easily seen with casing, so using Name: .. rather than name: ..

Detecting errors

These rules are straightforward, violations indicate that there's a good chance that you won't be able to run your Pipeline

• Missing Task definitions
• Missing Condition definitions
• Missing Pipeline definitions
• Missing TriggerTemplate definitions
• Missing TriggerBinding definitions
• Missing parameter declarations within Tasks
• Missing parameter declarations within Pipelines
• Missing parameter declarations within TriggerTemplates
• Missing volume definitions in Tasks
• Missing Task output results
• Missing required Pipeline parameters in TriggerTemplates
• Missing required Task parameters in Pipelines
• Missing required workspaces of Tasks referenced in Pipelines
• Missing required workspaces of Pipelines referenced in TriggerTemplates
• Extra parameters passed to Pipelines
• Extra parameters passed to Tasks
• Invalid runAfter conditions
• Invalid resourceVersion key
• Duplicate resources (of all supported resource kinds)
• Duplicate parameters name in Tasks
• Duplicate environment variables in Steps
• Duplicate PipelineRun's parameters name in TriggerTemplates
• Duplicate parameters name in TriggerBindings
• Duplicate parameters name in TriggerTemplates
• Duplicate parameters name in Pipelines
• Missing Task parameter value in Pipelines
• Invalid Task, Pipeline, TriggerTemplate, Condition parameter names (alpha-numeric characters, - and _ and can only start with alpha characters and _)
• Invalid Task, Pipeline, TriggerTemplate parameter value types (must be string, multiline string or array of strings)
• Invalid Task parameter syntax (using v1beta1 syntax in v1alpha1 defintions, and vice versa)
• Invalid (undefined) Workspace references in Tasks of Pipelines
• Missing referenced Task in another Task's parameter in Pipelines
• Cycle detection in each pipelines task dependency graph (based on runAfters, results and resource -> inputs)

Best practices

If you violate these rules, the Pipeline is probably going to be just fine, these rules are more like a collection of best practices that we collected while we were working with tekton.

• Unused Task parameters
• Unused Condition parameters
• Unused Pipeline parameters
• Unused TriggerTemplate parameters
• Unpinned images in Task steps
• kebab-case and OR camelCase naming violations
• Task & Pipeline definitions with tekton.dev/v1alpha1 apiVersion
• Missing TriggerBinding parameter values
• Usage of deprecated Condition instead of WhenExpression
• Usage of deprecated resources (resources marked with tekton.dev/deprecated label)
• Missing hashbang line from a Steps script

The default rule is for preferring kebab-case; camelCase is equally popular and many of the official examples on the Tekton website are in camel case. To use the rule that accepts camel case as well swap the rules in the .tektonrc.yaml file

---
rules: # error | warning | off
  prefer-kebab-case: off
  prefer-camel-kebab-case: warning

Configuring tekton-lint

You can configure tekton-lint with a configuration file (.tektonlintrc.yaml). You can decide which rules are enabled and at what error level. In addition you can specify external tekton tasks defined in a git repository; for example OpenToolChain provides a set of tasks that are helpful. But if you lint just your own tekton files there will be errors about not being able to find git-clone-repo for example. Not will any checks be made to see if your usage is correct.

Any task defined in the external-tasks section will be clone from git, into a local cache (defaults to ~/.tektonlint). Please make sure that you can git clone before running.

The configuration file should follow this format:

---
rules:
  rule-name: error | warning | off
external-tasks:
  - name: <tasks name>
    uri: http://github.com/....
    path: <sub dir of repo>

Example .tektonlintrc.yaml file:

---
rules:
  no-duplicate-param: error
  no-unused-param: warning
  no-deprecated-resource: off
external-tasks:
  - name: git-clone-repo
    uri: https://github.com/open-toolchain/tekton-catalog
    path: git
  - name: toolchain-extract-value
    uri: https://github.com/open-toolchain/tekton-catalog
    path: toolchain
  - name: doi-publish-build-record
    uri: https://github.com/open-toolchain/tekton-catalog
    path: devops-insights    
  - name: icr-publish
    uri: https://github.com/open-toolchain/tekton-catalog
    path: container-registry
  - name: iks-detch
    uri: https://github.com/open-toolchain/tekton-catalog
    path: kubernetes-service  

Search path for .tektonlintrc.yaml

• location specified on the command line with the --config option
• current working directory
• default values used if nothing else found

Custom Rules

In additional the default set of rules, custom rules can provided as node modules; the mechanism is similar that used by tools such as eslint.

An example is provided in custom_rules, and will be used in the examples below. Notes on writing rules are also in the README.md

Configuring

In the .tektonrc.yaml file add an object with names of the rules and node module that provides it. To load rules exported by the module custom_rules, and named under my_rules add the custom field to the yaml file.

---
rules:
  ....
external:tasks:
  ...
custom: 
 my_rules: custom_rules 
 # For debug and test, refer directly to the js file
 # my_rules: ../customer_rules/my_rules.js

Reporting

A module may report more than one rule. There is one rule in the example, and this flags up any task that starts with the work 'Task' (not meant to be serious rule, but an example!)

Running on the example-task.yaml file with the example configured adds a 4th report

./example-task.yaml
  10:14  warning  Invalid image: 'busybox'. Specify the image tag instead of using ':latest'          no-latest-image
   9:31  error    Undefined param 'contextDir' at .spec.steps[0].command[2] in 'Task-without-params'  no-undefined-param
  11:19  error    Undefined param 'contextDir' at .spec.steps[0].workingDir in 'Task-without-params'  no-undefined-param
   1:1   error    Tasks should not start with word 'Task'                                             my_rules#no-tasks-called-task

✖ 4 problems (3 errors, 1 warning)

Within the representation of the rule name here my_rules#no-tasks-called-task; if you want to turn off this rule, then you can adjust the list of rules in the .tektonrc.yaml as for another rule; Note that # in the name.

rules:
  ...
  my_rules#no-tasks-called-task: off

Issues?

Please raise an issue in the usual manner, please try and include a short sample Tekton file that shows the problem.

There is an internal logging system you can enable via setting and environment variable

TL_DEBUG=true tekton-lint <file.yaml>

This will write out a app.log file in pino json format - use pino-pretty to view