Go Hystrix

Hystrix Circuit Breaker Audit

Audit a Go service's Hystrix circuit breaker implementation across 7 dimensions: configuration tuning, error handling, code patterns, observability, naming conventions, testing, and fallback patterns. Produces a tiered report with quick-win code fixes and recommendations requiring team decisions.

Context

Go services using github.com/afex/hystrix-go implement circuit breakers to protect downstream dependencies. Common patterns include:

• hystrix.ConfigureCommand() in main.go to set timeouts, concurrency, and error thresholds
• hystrix.Go() with a channel+select pattern for async execution
• hystrix.GetCircuit() in instrumenting middleware for Prometheus metrics
• hystrix.NewStreamHandler() for real-time circuit monitoring

Instructions

0. Determine Audit Scope

• If $ARGUMENTS contains file paths or a subdirectory: scoped audit — only audit hystrix usage in those files
• If $ARGUMENTS is empty: full repo audit — audit the entire service in the current working directory
• If invoked by go-staff-engineer agent: follow the agent's scope directive

For scoped audits, skip dimensions where no relevant findings exist and produce a condensed report.

1. Find Hystrix Imports

• Check go.mod for github.com/afex/hystrix-go dependency
• Scan all *.go files for "github.com/afex/hystrix-go/hystrix" imports
• If no hystrix usage is found, report "No hystrix-go usage detected" and stop

2. Map Command Configurations

• Search for all hystrix.ConfigureCommand() calls (typically in main.go)
• For each command, extract:
  • Command name (first argument string)
  • Timeout value and whether it's hardcoded or config-driven
  • MaxConcurrentRequests value
  • ErrorPercentThreshold value
  • Whether SleepWindow or RequestVolumeThreshold are set (note if using defaults)

Build the Command Inventory Table:

3. Map Execution Sites

• Search for all hystrix.Go() and hystrix.Do() calls across *.go files
• For each call, record:
  • The command name string (must match a configured command)
  • The file and line number
  • Whether a fallback function is provided (second/third parameter)
  • The service method or dependency it protects
• Flag any execution sites where the command name does not match a configured command

4. Map Middleware and Wrappers

• Search for hystrix.GetCircuit() calls — these indicate monitoring/metrics integration
• Identify instrumenting middleware that exposes circuit status (typically a getCircuitStatus() helper)
• Note which metrics system is used (Prometheus, StatsD, etc.)

5. Identify Protected Dependencies

• For each hystrix command, trace the code inside the hystrix.Go()/hystrix.Do() closure to identify what external service or resource it protects
• Categorize each dependency: external API, cache (Redis), database, internal service, etc.

Output: A command map linking each command to its configuration, execution site, and protected dependency. This map is the foundation for all 7 dimension audits.

6. Audit Dimensions

For each dimension (1-7), read the corresponding reference file under references/, then run its checklist against the command map and source code. For each finding:

• Classify severity: Critical (misconfigured/ineffective), Warning (suboptimal but functional), Info (style/consistency)
• Tag as Quick Win (include before/after code) or Recommendation (describe the issue, note effort as S/M/L)

Dimension order:

1. Configuration Tuning — read references/configuration-tuning.md
2. Error Handling — read references/error-handling.md
3. Code Patterns — read references/code-patterns.md
4. Observability — read references/observability.md
5. Naming Conventions — read references/naming-conventions.md
6. Testing — read references/testing-patterns.md
7. Fallback Patterns — read references/fallback-patterns.md

7. Generate Report

Produce the audit report in this format. For dimensions with no findings, include the heading with "No issues found."

# Hystrix Audit Report: {service-name}

## Executive Summary
- **Commands audited:** {count}
- **Dependencies protected:** {list}
- **Overall health:** {Critical: N | Warning: N | Info: N}

### Quick Wins (ready to apply)
| # | Finding | Dimension | Severity | File:Line |
|---|---------|-----------|----------|-----------|
| 1 | ... | ... | ... | ... |

### Recommendations (team decision needed)
| # | Finding | Dimension | Severity | Effort |
|---|---------|-----------|----------|--------|
| 1 | ... | ... | ... | S/M/L |

---

## Command Inventory
| Command | Timeout | MaxConcurrent | ErrorThreshold | Protected Dependency | File:Line |
|---------|---------|---------------|----------------|---------------------|-----------|

---

## Dimension 1: Configuration Tuning
### Findings
{findings with severity badges}
### Quick Win Code
{before/after diffs for fixable items}

## Dimension 2: Error Handling
### Findings
{error filtering analysis, swallowed errors}
### Quick Win Code
{fixes where applicable}

## Dimension 3: Code Patterns
### Findings
{deviations from standard boilerplate}
### Quick Win Code
{normalization diffs}

## Dimension 4: Observability
### Findings
{metrics integration, stream handler, alerting gaps}
### Quick Win Code
{missing metrics registration, etc.}

## Dimension 5: Naming Conventions
### Findings
{inconsistent or non-traceable names}
### Quick Win Code
{renames where safe}

## Dimension 6: Testing
### Findings
{missing circuit breaker test coverage}
### Recommendations
{test patterns to add}

## Dimension 7: Fallback Patterns
### Findings
{flag missing fallbacks — no prescriptive fixes, defer to team}

Severity definitions:

• Critical — circuit breaker is misconfigured or ineffective (e.g., timeout higher than upstream timeout, circuit never trips)
• Warning — suboptimal but functional (e.g., uniform concurrency not tuned per dependency, missing sleep window config)
• Info — style/consistency issues (e.g., naming inconsistency, boilerplate deviation)

Effort sizing for recommendations:

• S — isolated change, single file
• M — multi-file change, requires testing
• L — architectural change, requires team alignment