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Add custom step executors to extend workflow capabilities.

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Overview

Step types are handlers that execute specific step configurations. Each type has a dedicated executor in internal/executor/.

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Steps to Add a New Step Type

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1. Define the Type Constant

Add to internal/core/types.go: 
// StepType represents the type of step
type StepType string

const (
    StepTypeBash          StepType = "bash"
    StepTypeFunction      StepType = "function"
    StepTypeForeach       StepType = "foreach"
    StepTypeParallelSteps StepType = "parallel-steps"
    StepTypeRemoteBash    StepType = "remote-bash"
    StepTypeHTTP          StepType = "http"
    StepTypeLLM           StepType = "llm"
    StepTypeMyNew         StepType = "mynew"  // Add your new type
)

​
2. Add Step Fields (if needed)

Add fields to internal/core/step.go: 
type Step struct {
    // Existing fields...

    // New fields for your step type
    MyNewField     string            `yaml:"my_new_field,omitempty"`
    MyNewConfig    *MyNewConfig      `yaml:"my_new_config,omitempty"`
}

type MyNewConfig struct {
    Option1 string `yaml:"option1,omitempty"`
    Option2 int    `yaml:"option2,omitempty"`
}

​
3. Create the Executor

Create internal/executor/mynew_executor.go: 
package executor

import (
    "context"

    "github.com/osmedeus/osmedeus-ng/internal/core"
    "github.com/osmedeus/osmedeus-ng/internal/template"
)

type MyNewExecutor struct {
    templateEngine *template.Engine
}

func NewMyNewExecutor(templateEngine *template.Engine) *MyNewExecutor {
    return &MyNewExecutor{
        templateEngine: templateEngine,
    }
}

func (e *MyNewExecutor) Execute(
    ctx context.Context,
    step *core.Step,
    execCtx *core.ExecutionContext,
) (*core.StepResult, error) {
    // 1. Render templates in step fields
    renderedField, err := e.templateEngine.Render(step.MyNewField, execCtx.Variables)
    if err != nil {
        return nil, fmt.Errorf("template render failed: %w", err)
    }

    // 2. Perform your step logic
    output, err := e.doSomething(ctx, renderedField, step.MyNewConfig)
    if err != nil {
        return &core.StepResult{
            Success: false,
            Error:   err,
        }, nil
    }

    // 3. Return result
    return &core.StepResult{
        Success: true,
        Output:  output,
    }, nil
}

func (e *MyNewExecutor) doSomething(
    ctx context.Context,
    field string,
    config *core.MyNewConfig,
) (string, error) {
    // Implementation here
    return "result", nil
}

​
4. Register in Dispatcher

Update internal/executor/dispatcher.go: 
type StepDispatcher struct {
    bashExecutor       *BashExecutor
    functionExecutor   *FunctionExecutor
    foreachExecutor    *ForeachExecutor
    parallelExecutor   *ParallelExecutor
    remoteBashExecutor *RemoteBashExecutor
    httpExecutor       *HTTPExecutor
    llmExecutor        *LLMExecutor
    myNewExecutor      *MyNewExecutor  // Add your executor
    runner             runner.Runner
}

func NewStepDispatcher(
    templateEngine *template.Engine,
    functionRegistry *functions.Registry,
    runner runner.Runner,
) *StepDispatcher {
    return &StepDispatcher{
        // Existing executors...
        myNewExecutor: NewMyNewExecutor(templateEngine),
        runner:        runner,
    }
}

func (d *StepDispatcher) Dispatch(
    ctx context.Context,
    step *core.Step,
    execCtx *core.ExecutionContext,
) (*core.StepResult, error) {
    switch step.Type {
    case core.StepTypeBash:
        return d.bashExecutor.Execute(ctx, step, execCtx, d.runner)
    // ... other cases ...
    case core.StepTypeMyNew:
        return d.myNewExecutor.Execute(ctx, step, execCtx)
    default:
        return nil, fmt.Errorf("unknown step type: %s", step.Type)
    }
}

​
5. Add Validation

Update internal/parser/validator.go: 
func (v *Validator) validateStep(step *core.Step) error {
    switch step.Type {
    // ... existing cases ...
    case core.StepTypeMyNew:
        return v.validateMyNewStep(step)
    }
    return nil
}

func (v *Validator) validateMyNewStep(step *core.Step) error {
    if step.MyNewField == "" {
        return fmt.Errorf("step '%s': my_new_field is required for mynew step type", step.Name)
    }
    return nil
}

​
6. Write Tests

Create internal/executor/mynew_executor_test.go: 
package executor

import (
    "context"
    "testing"

    "github.com/osmedeus/osmedeus-ng/internal/core"
    "github.com/osmedeus/osmedeus-ng/internal/template"
    "github.com/stretchr/testify/assert"
    "github.com/stretchr/testify/require"
)

func TestMyNewExecutor_Execute(t *testing.T) {
    engine := template.NewEngine()
    executor := NewMyNewExecutor(engine)

    step := &core.Step{
        Name:       "test-step",
        Type:       core.StepTypeMyNew,
        MyNewField: "test-value",
    }

    execCtx := &core.ExecutionContext{
        Variables: map[string]interface{}{
            "target": "example.com",
        },
    }

    result, err := executor.Execute(context.Background(), step, execCtx)

    require.NoError(t, err)
    assert.True(t, result.Success)
    assert.NotEmpty(t, result.Output)
}

​
Example: Custom Notification Step

// internal/executor/notify_executor.go

type NotifyExecutor struct {
    templateEngine *template.Engine
}

func (e *NotifyExecutor) Execute(
    ctx context.Context,
    step *core.Step,
    execCtx *core.ExecutionContext,
) (*core.StepResult, error) {
    // Render message template
    message, err := e.templateEngine.Render(step.NotifyMessage, execCtx.Variables)
    if err != nil {
        return nil, err
    }

    // Send notification based on channel
    switch step.NotifyChannel {
    case "slack":
        err = e.sendSlack(ctx, step.NotifyConfig.WebhookURL, message)
    case "discord":
        err = e.sendDiscord(ctx, step.NotifyConfig.WebhookURL, message)
    case "telegram":
        err = e.sendTelegram(ctx, step.NotifyConfig, message)
    }

    if err != nil {
        return &core.StepResult{Success: false, Error: err}, nil
    }

    return &core.StepResult{Success: true, Output: "Notification sent"}, nil
}
Usage in workflow: 
- name: notify-complete
  type: notify
  notify_channel: slack
  notify_message: "Scan completed for {{target}}"
  notify_config:
    webhook_url: "{{slack_webhook}}"

​
Best Practices

  1. Always render templates before using step fields
  2. Support context cancellation via ctx.Done()
  3. Return meaningful errors with context
  4. Export useful values via StepResult
  5. Write comprehensive tests
  6. Add validation rules for required fields

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Next Steps