mirror of https://github.com/actions/toolkit
150 lines
5.6 KiB
Markdown
150 lines
5.6 KiB
Markdown
# Problem Matchers
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Problem Matchers are a way to scan the output of actions for a specified regex pattern and surface that information prominently in the UI. Both [GitHub Annotations](https://developer.github.com/v3/checks/runs/#annotations-object-1) and log file decorations are created when a match is detected.
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## Limitations
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Currently, GitHub Actions limit the annotation count in a workflow run.
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- 10 warning annotations and 10 error annotations per step
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- 50 annotations per job (sum of annotations from all the steps)
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- 50 annotations per run (separate from the job annotations, these annotations aren’t created by users)
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If your workflow may exceed these annotation counts, consider filtering of the log messages which the Problem Matcher is exposed to (e.g. by PR touched files, lines, or other).
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## Single Line Matchers
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Let's consider the ESLint compact output:
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```
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badFile.js: line 50, col 11, Error - 'myVar' is defined but never used. (no-unused-vars)
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```
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We can define a problem matcher in json that detects input in that format:
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```json
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{
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"problemMatcher": [
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{
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"owner": "eslint-compact",
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"pattern": [
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{
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"regexp": "^(.+):\\sline\\s(\\d+),\\scol\\s(\\d+),\\s(Error|Warning|Info)\\s-\\s(.+)\\s\\((.+)\\)$",
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"file": 1,
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"line": 2,
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"column": 3,
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"severity": 4,
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"message": 5,
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"code": 6
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}
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]
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}
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]
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}
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```
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The following fields are available for problem matchers:
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```
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{
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owner: an ID field that can be used to remove or replace the problem matcher. **required**
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severity: indicates the default severity, either 'warning' or 'error' case-insensitive. Defaults to 'error'
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pattern: [
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{
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regexp: the regex pattern that provides the groups to match against **required**
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file: a group number containing the file name
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fromPath: a group number containing a filepath used to root the file (e.g. a project file)
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line: a group number containing the line number
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column: a group number containing the column information
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severity: a group number containing either 'warning' or 'error' case-insensitive. Defaults to `error`
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code: a group number containing the error code
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message: a group number containing the error message. **required** at least one pattern must set the message
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loop: whether to loop until a match is not found, only valid on the last pattern of a multipattern matcher
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}
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]
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}
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```
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## Multiline Matching
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Consider the following output:
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```
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test.js
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1:0 error Missing "use strict" statement strict
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5:10 error 'addOne' is defined but never used no-unused-vars
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✖ 2 problems (2 errors, 0 warnings)
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```
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The file name is printed once, yet multiple error lines are printed. The `loop` keyword provides a way to discover multiple errors in outputs.
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The eslint-stylish problem matcher defined below catches that output, and creates two annotations from it.
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```
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{
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"problemMatcher": [
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{
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"owner": "eslint-stylish",
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"pattern": [
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{
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// Matches the 1st line in the output
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"regexp": "^([^\\s].*)$",
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"file": 1
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},
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{
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// Matches the 2nd and 3rd line in the output
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"regexp": "^\\s+(\\d+):(\\d+)\\s+(error|warning|info)\\s+(.*)\\s\\s+(.*)$",
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// File is carried through from above, so we define the rest of the groups
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"line": 1,
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"column": 2,
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"severity": 3,
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"message": 4,
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"code": 5,
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"loop": true
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}
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]
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}
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]
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}
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```
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The first pattern matches the `test.js` line and records the file information. This line is not decorated in the UI.
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The second pattern loops through the remaining lines with `loop: true` until it fails to find a match, and surfaces these lines prominently in the UI.
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Note that the pattern matches must be on consecutive lines. The following would not result in any match findings.
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```
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test.js
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extraneous log line of no interest
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1:0 error Missing "use strict" statement strict
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5:10 error 'addOne' is defined but never used no-unused-vars
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✖ 2 problems (2 errors, 0 warnings)
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```
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## Adding and Removing Problem Matchers
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Problem Matchers are enabled and removed via the toolkit [commands](commands.md#problem-matchers).
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## Duplicate Problem Matchers
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Registering two problem-matchers with the same owner will result in only the problem matcher registered last running.
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## Examples
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Some of the starter actions are already using problem matchers, for example:
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- [setup-node](https://github.com/actions/setup-node/tree/main/.github)
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- [setup-python](https://github.com/actions/setup-python/tree/main/.github)
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- [setup-go](https://github.com/actions/setup-go/tree/main/.github)
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- [setup-dotnet](https://github.com/actions/setup-dotnet/tree/main/.github)
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## Troubleshooting
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### Regular expression not matching
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Use ECMAScript regular expression syntax when testing patterns.
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### File property getting dropped
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[Enable debug logging](https://help.github.com/en/actions/configuring-and-managing-workflows/managing-a-workflow-run#enabling-debug-logging) to determine why the file is getting dropped.
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This usually happens when the file does not exist or is not under the workflow repo.
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