Patterns

Retry and timeout

How it works

1. Run the first attempt.
2. If it fails and Retries > 0: wait RetryDelay, then retry — up to Retries additional times.
3. If Timeout > 0: each individual attempt is cancelled after that duration and returns "timed out after {duration}".
4. If all attempts fail, the last error is returned.

Example: wait for a service to start

worky.Check{
    Description: "Server responds on :8080",
    Run:         checks.HTTPStatus("http://localhost:8080", 200),
    Timeout:     5 * time.Second,
    Retries:     5,
    RetryDelay:  2 * time.Second,
}

This makes up to 6 attempts (1 initial + 5 retries), waiting 2 seconds between each, with each attempt timing out after 5 seconds.

---

Custom check function

Any func(context.Context) error is a valid Run value. Use this for validation logic that has no built-in helper. The context carries the per-attempt deadline set by Timeout, so pass it to any blocking calls:

worky.Check{
    Description: "config.yaml is valid YAML",
    Run: func(_ context.Context) error {
        data, err := os.ReadFile("config.yaml")
        if err != nil {
            return err
        }
        var out any
        return yaml.Unmarshal(data, &out)
    },
}

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Shared state between chapters

Checks in later chapters can read values captured by checks in earlier chapters using closure variables:

var deployedURL string

chapters := []worky.Chapter{
    {
        ID:   "01",
        Name: "Deploy",
        Checks: []worky.Check{
            {
                Description: "DEPLOY_URL is set",
                Run: func(_ context.Context) error {
                    deployedURL = os.Getenv("DEPLOY_URL")
                    if deployedURL == "" {
                        return errors.New("DEPLOY_URL is not set")
                    }
                    return nil
                },
            },
        },
    },
    {
        ID:   "02",
        Name: "Verify deploy",
        Checks: []worky.Check{
            {
                Description: "Deploy responds with 200",
                Run: func(ctx context.Context) error {
                    return checks.HTTPStatus(deployedURL, 200)(ctx)
                },
            },
        },
    },
}

deployedURL is populated when chapter 01’s check runs and is available to chapter 02’s check because both closures close over the same variable.

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Further reading

• Checks — built-in check functions reference
• Troubleshooting — common check error messages and how to fix them