Files
act_runner/pkg/runner/runner.go
Pascal Zimmermann 15dd63a839 feat: Add support for Dynamic Matrix Strategies with Job Outputs (#149)
# Matrix Strategy: Support for Scalar Values and Template Expressions

## 🎯 Overview

This Pull Request implements support for **scalar values and template expressions** in matrix strategies. Previously, every matrix value had to be declared as a YAML array — a bare scalar like `os: ubuntu-latest` or `version: ${{ fromJSON(...) }}` caused silent failures. Now, scalars are automatically wrapped into single-element arrays, enabling the `${{ fromJSON(...) }}` pattern that is commonly used in GitHub Actions workflows for dynamic matrix generation.

## ⚠️ Semantic Changes

Two subtle behavior changes are introduced that are worth understanding:

### 1. Scalar matrix values now produce a 1-element matrix expansion

**Before this PR:** A scalar value like

```yaml
strategy:
  matrix:
    os: ubuntu-latest   # no brackets
```

failed to decode as `map[string][]interface{}`, so `Matrix()` returned `nil`. The job ran **once, without any matrix context** (`matrix.os` was undefined).

**After this PR:** The same input is wrapped to `["ubuntu-latest"]`. The job runs **one matrix iteration** with `matrix.os = "ubuntu-latest"` set.

> **Impact on existing workflows:** Workflows that accidentally used bare scalars instead of arrays will now run with a matrix context where they previously did not. The functional result is usually the same, but `matrix.*` variables are now populated. This is considered an improvement, but is a semantic change.

---

### 2. Unevaluated template expressions fall back to a literal string value

The actual resolution of `${{ fromJSON(needs.job1.outputs.versions) }}` into an array happens **before** `Matrix()` is called — in `EvaluateYamlNode` inside `pkg/runner/runner.go`. This PR does not change that evaluation path.

If evaluation succeeds → the YAML node already contains a proper array → `Matrix()` decodes it normally.

If evaluation **fails or is skipped** (e.g., expression not yet resolved) → the scalar string is now wrapped as `["${{ fromJSON(...) }}"]` → the job runs **one iteration with the literal unexpanded string** as the matrix value.

> **Note:** The test `TestJobMatrix/matrix_with_template_expression` covers this fallback path, not the successful resolution path. The literal-wrap behavior is the fallback, not the primary mechanism for template expression support.

---

## 🔑 Key Changes

### 1. Flexible Matrix Decoding (`pkg/model/workflow.go`)

#### New Helper Function: `normalizeMatrixValue`
```go
func normalizeMatrixValue(key string, val interface{}) ([]interface{}, error)
```
- Converts a single matrix value to the expected array format
- Handles three cases:
  1. **Arrays**: Pass through unchanged
  2. **Scalars**: Wrap in single-element array (including template expressions)
  3. **Invalid types** (maps, etc.): Return error to detect misconfigurations early

**Supported scalar types:**
- `string` — including unevaluated template expressions
- `int`, `float64` — numeric values
- `bool` — boolean values
- `nil` — null values

#### Enhanced `Matrix()` Method

**Before:**
```go
func (j *Job) Matrix() map[string][]interface{} {
    if j.Strategy.RawMatrix.Kind == yaml.MappingNode {
        var val map[string][]interface{}
        if !decodeNode(j.Strategy.RawMatrix, &val) {
            return nil
        }
        return val
    }
    return nil
}
```

**After:**
```go
func (j *Job) Matrix() map[string][]interface{} {
    if j.Strategy == nil || j.Strategy.RawMatrix.Kind != yaml.MappingNode {
        return nil
    }

    // First decode to flexible map[string]interface{} to handle scalars and arrays
    var flexVal map[string]interface{}
    err := j.Strategy.RawMatrix.Decode(&flexVal)
    if err != nil {
        // If that fails, try the strict array format
        var val map[string][]interface{}
        if !decodeNode(j.Strategy.RawMatrix, &val) {
            return nil
        }
        return val
    }

    // Convert flexible format to expected format with validation
    val := make(map[string][]interface{})
    for k, v := range flexVal {
        normalized, err := normalizeMatrixValue(k, v)
        if err != nil {
            log.Errorf("matrix validation error: %v", err)
            return nil
        }
        val[k] = normalized
    }
    return val
}
```

**Key improvements:**
- Handles unevaluated template expressions as scalar strings
- Automatic conversion to array format for consistent processing
- Validation to catch nested maps and invalid configurations
- Fallback to strict array format decoding for backward compatibility
- Early nil check for strategy to prevent nil pointer panics

---

## 🎁 Use Cases

### Example 1: Template Expression in Matrix (primary motivation)
```yaml
jobs:
  setup:
    runs-on: ubuntu-latest
    outputs:
      versions: ${{ steps.version-map.outputs.versions }}
    steps:
      - id: version-map
        run: echo "versions=[\"1.17\",\"1.18\",\"1.19\"]" >> $GITHUB_OUTPUT

  test:
    needs: setup
    strategy:
      matrix:
        # EvaluateYamlNode resolves this to an array before Matrix() is called
        version: ${{ fromJSON(needs.setup.outputs.versions) }}
    runs-on: ubuntu-latest
    steps:
      - run: echo "Testing version ${{ matrix.version }}"
```

### Example 2: Mixed Scalar and Array Values
```yaml
jobs:
  build:
    strategy:
      matrix:
        os: [ubuntu-latest, windows-latest]  # Array — unchanged
        go-version: 1.19                      # Scalar — wrapped to [1.19]
        node: [14, 16, 18]                    # Array — unchanged
    runs-on: ${{ matrix.os }}
```

### Example 3: Single Value Matrix
```yaml
jobs:
  deploy:
    strategy:
      matrix:
        environment: production  # Scalar — wrapped to ["production"]
    runs-on: ubuntu-latest
```

---

##  Benefits

-  **Feature Parity with GitHub Actions**: Supports template expressions in matrix strategies
- 🔒 **Robust Validation**: Detects misconfigured matrices (nested maps) early
- 🔄 **Backward Compatible**: Existing array-based workflows continue to work
- 📝 **Clear Error Messages**: Helpful validation messages for debugging
- 🛡️ **Type Safety**: Handles all YAML scalar types correctly

---

## 🚀 Breaking Changes

**Technically none in a strictly backward-incompatible sense**, but two semantic changes exist (see [⚠️ Semantic Changes](#️-semantic-changes-read-before-merging) above):

1. Scalar matrix values now iterate (previously they caused a `nil` matrix / no iteration)
2. Unevaluated template strings now produce a literal iteration instead of skipping

Both changes are improvements in practice, but downstream users should be aware.

---

## 📚 Related Work

- Related Gitea Server PR: [go-gitea/gitea#36564](https://github.com/go-gitea/gitea/pull/36564)
- Enables dynamic matrix generation from job outputs
- Supports advanced CI/CD patterns used in GitHub Actions

## 🔗 References

- [GitHub Actions: Matrix strategies](https://docs.github.com/en/actions/using-jobs/using-a-matrix-for-your-jobs)
- [GitHub Actions: Expression syntax](https://docs.github.com/en/actions/learn-github-actions/expressions)
- [GitHub Actions: `fromJSON` in matrix context](https://docs.github.com/en/actions/using-workflows/workflow-syntax-for-github-actions#jobsjob_idstrategymatrix)

Reviewed-on: https://gitea.com/gitea/act/pulls/149
Reviewed-by: silverwind <2021+silverwind@noreply.gitea.com>
Co-authored-by: Pascal Zimmermann <pascal.zimmermann@theiotstudio.com>
Co-committed-by: Pascal Zimmermann <pascal.zimmermann@theiotstudio.com>
2026-04-19 22:36:34 +00:00

332 lines
14 KiB
Go

package runner
import (
"context"
"encoding/json"
"fmt"
"os"
"runtime"
"sync"
"time"
"github.com/nektos/act/pkg/common"
"github.com/nektos/act/pkg/model"
docker_container "github.com/docker/docker/api/types/container"
log "github.com/sirupsen/logrus"
)
// Runner provides capabilities to run GitHub actions
type Runner interface {
NewPlanExecutor(plan *model.Plan) common.Executor
}
// Config contains the config for a new runner
type Config struct {
Actor string // the user that triggered the event
Workdir string // path to working directory
ActionCacheDir string // path used for caching action contents
ActionOfflineMode bool // when offline, use caching action contents
BindWorkdir bool // bind the workdir to the job container
EventName string // name of event to run
EventPath string // path to JSON file to use for event.json in containers
DefaultBranch string // name of the main branch for this repository
ReuseContainers bool // reuse containers to maintain state
ForcePull bool // force pulling of the image, even if already present
ForceRebuild bool // force rebuilding local docker image action
LogOutput bool // log the output from docker run
JSONLogger bool // use json or text logger
LogPrefixJobID bool // switches from the full job name to the job id
Env map[string]string // env for containers
Inputs map[string]string // manually passed action inputs
Secrets map[string]string // list of secrets
Vars map[string]string // list of vars
Token string // GitHub token
InsecureSecrets bool // switch hiding output when printing to terminal
Platforms map[string]string // list of platforms
Privileged bool // use privileged mode
UsernsMode string // user namespace to use
ContainerArchitecture string // Desired OS/architecture platform for running containers
ContainerDaemonSocket string // Path to Docker daemon socket
ContainerOptions string // Options for the job container
UseGitIgnore bool // controls if paths in .gitignore should not be copied into container, default true
GitHubInstance string // GitHub instance to use, default "github.com"
ContainerCapAdd []string // list of kernel capabilities to add to the containers
ContainerCapDrop []string // list of kernel capabilities to remove from the containers
AutoRemove bool // controls if the container is automatically removed upon workflow completion
ArtifactServerPath string // the path where the artifact server stores uploads
ArtifactServerAddr string // the address the artifact server binds to
ArtifactServerPort string // the port the artifact server binds to
NoSkipCheckout bool // do not skip actions/checkout
RemoteName string // remote name in local git repo config
ReplaceGheActionWithGithubCom []string // Use actions from GitHub Enterprise instance to GitHub
ReplaceGheActionTokenWithGithubCom string // Token of private action repo on GitHub.
Matrix map[string]map[string]bool // Matrix config to run
ContainerNetworkMode docker_container.NetworkMode // the network mode of job containers (the value of --network)
ActionCache ActionCache // Use a custom ActionCache Implementation
PresetGitHubContext *model.GithubContext // the preset github context, overrides some fields like DefaultBranch, Env, Secrets etc.
EventJSON string // the content of JSON file to use for event.json in containers, overrides EventPath
ContainerNamePrefix string // the prefix of container name
ContainerMaxLifetime time.Duration // the max lifetime of job containers
DefaultActionInstance string // the default actions web site
PlatformPicker func(labels []string) string // platform picker, it will take precedence over Platforms if isn't nil
JobLoggerLevel *log.Level // the level of job logger
ValidVolumes []string // only volumes (and bind mounts) in this slice can be mounted on the job container or service containers
InsecureSkipTLS bool // whether to skip verifying TLS certificate of the Gitea instance
MaxParallel int // max parallel jobs to run across all workflows (0 = no limit, uses CPU count)
}
// GetToken: Adapt to Gitea
func (c Config) GetToken() string {
token := c.Secrets["GITHUB_TOKEN"]
if c.Secrets["GITEA_TOKEN"] != "" {
token = c.Secrets["GITEA_TOKEN"]
}
return token
}
type caller struct {
runContext *RunContext
updateResultLock sync.Mutex // For Gitea
reusedWorkflowJobResults map[string]string // For Gitea
}
type runnerImpl struct {
config *Config
eventJSON string
caller *caller // the job calling this runner (caller of a reusable workflow)
}
// New Creates a new Runner
func New(runnerConfig *Config) (Runner, error) {
runner := &runnerImpl{
config: runnerConfig,
}
return runner.configure()
}
func (runner *runnerImpl) configure() (Runner, error) {
runner.eventJSON = "{}"
if runner.config.EventJSON != "" {
runner.eventJSON = runner.config.EventJSON
} else if runner.config.EventPath != "" {
log.Debugf("Reading event.json from %s", runner.config.EventPath)
eventJSONBytes, err := os.ReadFile(runner.config.EventPath)
if err != nil {
return nil, err
}
runner.eventJSON = string(eventJSONBytes)
} else if len(runner.config.Inputs) != 0 {
eventMap := map[string]map[string]string{
"inputs": runner.config.Inputs,
}
eventJSON, err := json.Marshal(eventMap)
if err != nil {
return nil, err
}
runner.eventJSON = string(eventJSON)
}
return runner, nil
}
// NewPlanExecutor ...
//
//nolint:gocyclo // function handles many cases
func (runner *runnerImpl) NewPlanExecutor(plan *model.Plan) common.Executor {
maxJobNameLen := 0
stagePipeline := make([]common.Executor, 0)
log.Debugf("Plan Stages: %v", plan.Stages)
for i := range plan.Stages {
stage := plan.Stages[i]
stagePipeline = append(stagePipeline, func(ctx context.Context) error {
pipeline := make([]common.Executor, 0)
for _, run := range stage.Runs {
log.Debugf("Stages Runs: %v", stage.Runs)
stageExecutor := make([]common.Executor, 0)
job := run.Job()
log.Debugf("Job.Name: %v", job.Name)
log.Debugf("Job.RawNeeds: %v", job.RawNeeds)
log.Debugf("Job.RawRunsOn: %v", job.RawRunsOn)
log.Debugf("Job.Env: %v", job.Env)
log.Debugf("Job.If: %v", job.If)
for step := range job.Steps {
if nil != job.Steps[step] {
log.Debugf("Job.Steps: %v", job.Steps[step].String())
}
}
log.Debugf("Job.TimeoutMinutes: %v", job.TimeoutMinutes)
log.Debugf("Job.Services: %v", job.Services)
log.Debugf("Job.Strategy: %v", job.Strategy)
log.Debugf("Job.RawContainer: %v", job.RawContainer)
log.Debugf("Job.Defaults.Run.Shell: %v", job.Defaults.Run.Shell)
log.Debugf("Job.Defaults.Run.WorkingDirectory: %v", job.Defaults.Run.WorkingDirectory)
log.Debugf("Job.Outputs: %v", job.Outputs)
log.Debugf("Job.Uses: %v", job.Uses)
log.Debugf("Job.With: %v", job.With)
// log.Debugf("Job.RawSecrets: %v", job.RawSecrets)
log.Debugf("Job.Result: %v", job.Result)
if job.Strategy != nil {
log.Debugf("Job.Strategy.FailFast: %v", job.Strategy.FailFast)
log.Debugf("Job.Strategy.MaxParallel: %v", job.Strategy.MaxParallel)
log.Debugf("Job.Strategy.FailFastString: %v", job.Strategy.FailFastString)
log.Debugf("Job.Strategy.MaxParallelString: %v", job.Strategy.MaxParallelString)
log.Debugf("Job.Strategy.RawMatrix: %v", job.Strategy.RawMatrix)
strategyRc := runner.newRunContext(ctx, run, nil)
// Resolve template expressions in the matrix node before Matrix() is called.
// On failure the literal string is kept and normalizeMatrixValue wraps it as a fallback.
if err := strategyRc.NewExpressionEvaluator(ctx).EvaluateYamlNode(ctx, &job.Strategy.RawMatrix); err != nil {
log.Errorf("Error while evaluating matrix: %v", err)
}
}
var matrixes []map[string]any
if m, err := job.GetMatrixes(); err != nil {
log.Errorf("Error while get job's matrix: %v", err)
} else {
log.Debugf("Job Matrices: %v", m)
log.Debugf("Runner Matrices: %v", runner.config.Matrix)
matrixes = selectMatrixes(m, runner.config.Matrix)
}
log.Debugf("Final matrix after applying user inclusions '%v'", matrixes)
maxParallel := 4
if job.Strategy != nil {
// Ensure GetMaxParallel() is called if MaxParallel is still 0
if job.Strategy.MaxParallel == 0 {
job.Strategy.MaxParallel = job.Strategy.GetMaxParallel()
}
maxParallel = job.Strategy.MaxParallel
log.Debugf("Using job.Strategy.MaxParallel: %d", maxParallel)
}
if len(matrixes) < maxParallel {
log.Debugf("Adjusting maxParallel from %d to %d (number of matrix combinations)", maxParallel, len(matrixes))
maxParallel = len(matrixes)
}
log.Infof("Running job with maxParallel=%d for %d matrix combinations", maxParallel, len(matrixes))
for i, matrix := range matrixes {
rc := runner.newRunContext(ctx, run, matrix)
rc.JobName = rc.Name
if len(matrixes) > 1 {
rc.Name = fmt.Sprintf("%s-%d", rc.Name, i+1)
}
if len(rc.String()) > maxJobNameLen {
maxJobNameLen = len(rc.String())
}
if rc.caller != nil { // For Gitea
rc.caller.setReusedWorkflowJobResult(rc.JobName, "pending")
}
stageExecutor = append(stageExecutor, func(ctx context.Context) error {
jobName := fmt.Sprintf("%-*s", maxJobNameLen, rc.String())
executor, err := rc.Executor()
if err != nil {
return err
}
return executor(common.WithJobErrorContainer(WithJobLogger(ctx, rc.Run.JobID, jobName, rc.Config, &rc.Masks, matrix)))
})
}
pipeline = append(pipeline, common.NewParallelExecutor(maxParallel, stageExecutor...))
}
// For pipeline execution:
// - If only 1 element: run it directly (no need for additional parallelization)
// - If multiple elements: run them in parallel up to maxParallel or ncpu
if len(pipeline) == 0 {
return nil
}
if len(pipeline) == 1 {
// Single run/job: execute directly without additional parallelization wrapper
// This ensures max-parallel is the only limiting factor
log.Debugf("Single pipeline element, executing directly")
return pipeline[0](ctx)
}
// Multiple runs/jobs: execute in parallel up to maxParallel (if set) or ncpu
parallelism := runtime.NumCPU()
// If MaxParallel is set in config, use it
if runner.config.MaxParallel > 0 {
parallelism = runner.config.MaxParallel
log.Debugf("Using configured max-parallel: %d", parallelism)
} else {
log.Debugf("Using CPU count for parallelism: %d", parallelism)
}
// Don't exceed the number of pipeline elements
if parallelism > len(pipeline) {
parallelism = len(pipeline)
}
log.Infof("Executing %d pipeline elements with parallelism %d", len(pipeline), parallelism)
return common.NewParallelExecutor(parallelism, pipeline...)(ctx)
})
}
return common.NewPipelineExecutor(stagePipeline...).Then(handleFailure(plan))
}
func handleFailure(plan *model.Plan) common.Executor {
return func(ctx context.Context) error {
for _, stage := range plan.Stages {
for _, run := range stage.Runs {
if run.Job().Result == "failure" {
return fmt.Errorf("Job '%s' failed", run.String())
}
}
}
return nil
}
}
func selectMatrixes(originalMatrixes []map[string]any, targetMatrixValues map[string]map[string]bool) []map[string]any {
matrixes := make([]map[string]any, 0)
for _, original := range originalMatrixes {
flag := true
for key, val := range original {
if allowedVals, ok := targetMatrixValues[key]; ok {
valToString := fmt.Sprintf("%v", val)
if _, ok := allowedVals[valToString]; !ok {
flag = false
}
}
}
if flag {
matrixes = append(matrixes, original)
}
}
return matrixes
}
func (runner *runnerImpl) newRunContext(ctx context.Context, run *model.Run, matrix map[string]any) *RunContext {
rc := &RunContext{
Config: runner.config,
Run: run,
EventJSON: runner.eventJSON,
StepResults: make(map[string]*model.StepResult),
Matrix: matrix,
caller: runner.caller,
}
rc.ExprEval = rc.NewExpressionEvaluator(ctx)
rc.Name = rc.ExprEval.Interpolate(ctx, run.String())
return rc
}
// For Gitea
func (c *caller) setReusedWorkflowJobResult(jobName, result string) {
c.updateResultLock.Lock()
defer c.updateResultLock.Unlock()
c.reusedWorkflowJobResults[jobName] = result
}