production ready enhancements

[hoangsonww]

This pull request introduces a full production-ready DevOps and developer workflow for the Post Analyzer Webserver. It adds comprehensive CI/CD automation, Docker support, environment-based configuration, and developer tooling to streamline development, testing, deployment, and migration.

CI/CD & Automation:

• Adds a complete GitHub Actions pipeline for linting, testing (including PostgreSQL integration), building, Docker image creation, security scanning, and deployment.
• Introduces a Makefile with commands for building, testing, formatting, linting, Docker operations, database management, and more to standardize local development workflows.

Productionization & Deployment:

• Provides a multi-stage Dockerfile for secure, reproducible builds and deployment, including non-root execution, health checks, and asset management.
• Adds a .env.example file with all necessary configuration options for different environments (development, staging, production), supporting both file and PostgreSQL storage.

Migration & Documentation:

• Supplies a detailed migration guide (MIGRATION_GUIDE.md) to help users upgrade from v1.0 to a production-ready v2.0, covering architecture changes, configuration, data migration, troubleshooting, and feature comparisons.

---

CI/CD and Developer Workflow

• Added .github/workflows/ci-cd.yml for automated linting, testing (with PostgreSQL), build, Docker image creation/push, security scanning, and deployment via GitHub Actions.
• Introduced a comprehensive Makefile for standardized local development, including commands for build, test, lint, Docker, database, and environment setup.

Productionization and Deployment

• Added a multi-stage Dockerfile for secure, minimal, and production-ready builds, including non-root user, health checks, and asset copying.
• Provided .env.example to document and facilitate environment-based configuration for all deployment scenarios.

Migration and Documentation

• Created MIGRATION_GUIDE.md with step-by-step instructions for upgrading, configuration, troubleshooting, and a feature matrix comparing v1.0 and v2.0.

[github-advanced-security]

This pull request sets up GitHub code scanning for this repository. Once the scans have completed and the checks have passed, the analysis results for this pull request branch will appear on this overview. Once you merge this pull request, the 'Security' tab will show more code scanning analysis results (for example, for the default branch). Depending on your configuration and choice of analysis tool, future pull requests will be annotated with code scanning analysis results. For more information about GitHub code scanning, check out the documentation.

[gemini-code-assist]

Summary of Changes

Hello @hoangsonww, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request significantly upgrades the Post Analyzer Webserver to a production-ready state. It introduces a robust DevOps and developer workflow, including automated CI/CD, Dockerization, and environment-based configuration. The application's architecture has been modularized, enhancing its API capabilities with new endpoints for managing and analyzing posts, and improving observability through structured logging and Prometheus metrics. Comprehensive documentation and a migration guide are also provided to facilitate adoption and maintenance.

Highlights

• Comprehensive CI/CD & Automation: Introduced a full GitHub Actions pipeline for linting, testing (with PostgreSQL), building, Docker image creation, security scanning, and deployment. A Makefile standardizes local development workflows.
• Production-Ready Deployment: Added a multi-stage Dockerfile for secure, reproducible builds and deployments, including non-root execution and health checks. Environment-based configuration is managed via a .env.example file.
• Enhanced API Capabilities: Implemented new REST API endpoints for full CRUD operations, bulk post creation, data export (JSON/CSV), and character frequency analytics, complete with detailed API_DOCUMENTATION.md and api-docs.yaml.
• Architectural Overhaul & Observability: Refactored the application into modular packages with a storage abstraction layer, comprehensive middleware stack, structured JSON logging, Prometheus metrics, and request tracing.
• Migration & Documentation: Provided a detailed MIGRATION_GUIDE.md to assist users in upgrading from v1.0 to v2.0, covering architectural changes, configuration, data migration, and a feature comparison matrix. A new README_PRODUCTION.md outlines the production-ready features.
• Improved Web Interface: The home.html template has been updated to support client-side character frequency analysis, providing a more interactive user experience.

Ignored Files

• Ignored by pattern: .github/workflows/** (1)
  • .github/workflows/ci-cd.yml

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[gemini-code-assist]

Code Review

This is an impressive pull request that significantly matures the application towards a production-ready state. The introduction of a proper project structure, Docker support, CI/CD, configuration management, and observability features like logging and metrics are all excellent additions. The code is well-organized and follows many Go best practices. My review focuses on several critical and high-severity issues related to concurrency safety, performance, and security that should be addressed before this can be considered truly production-ready. I've also included several medium-severity suggestions to further improve code quality, consistency, and maintainability.

[gemini-code-assist]

The MemoryCache is not safe for concurrent use. The data map is accessed and modified from multiple goroutines (HTTP handlers, cleanup goroutine) without any synchronization. This will lead to race conditions. You must add a mutex to protect access to the map.

Suggested change

	type MemoryCache struct {
	data map[string]cacheEntry
	}
	type MemoryCache struct {
	data map[string]cacheEntry
	mu sync.RWMutex
	}

[gemini-code-assist]

To fix the race condition, you need to use a read lock here to allow for concurrent reads.

func (c *MemoryCache) Get(ctx context.Context, key string, value interface{}) error {
	c.mu.RLock()
	defer c.mu.RUnlock()
	entry, exists := c.data[key]

[gemini-code-assist]

To fix the race condition, you need to use a write lock here as you are modifying the map.

func (c *MemoryCache) Set(ctx context.Context, key string, value interface{}, ttl time.Duration) error {
	c.mu.Lock()
	defer c.mu.Unlock()
	data, err := json.Marshal(value)
	if err != nil {
		return err
	}

[gemini-code-assist]

This implementation of GetAll is highly inefficient for a production system. It fetches all posts from the database into memory and then performs filtering, sorting, and pagination. For a large dataset, this will cause excessive memory usage and slow performance. These operations should be pushed down to the database layer to be executed as part of the SQL query (using WHERE, ORDER BY, LIMIT, and OFFSET clauses).

[gemini-code-assist]

Hardcoding secrets like database passwords in docker-compose.yml is a security risk. It's better to use environment variable substitution and define the actual values in a local .env file, which is already git-ignored. This applies to DB_PASSWORD and GF_SECURITY_ADMIN_PASSWORD as well.

      POSTGRES_PASSWORD: ${POSTGRES_PASSWORD}

[gemini-code-assist]

The responseWriter struct and its methods are nearly identical to metricsResponseWriter in internal/metrics/metrics.go. This code duplication should be refactored. Consider creating a single, shared response writer wrapper that can be used by both the logging and metrics middlewares, or have one middleware wrap the other's response writer.

[gemini-code-assist]

While this custom router works for the current needs, it's manually parsing paths and dispatching methods, which can become complex and error-prone as the API grows. For a production-ready application, it is strongly recommended to use a well-established, battle-tested routing library like chi or gorilla/mux. They provide more robust and feature-rich routing, parameter extraction, and middleware management.

[gemini-code-assist]

This implementation of getSliceEnv doesn't handle whitespace around commas. For an input like "a, b, c", it will produce ["a", " b", " c"]. A more robust implementation would be to split the string by the comma and then trim whitespace from each part.

func getSliceEnv(key string, defaultValue []string) []string {
	if value := os.Getenv(key); value != "" {
		parts := strings.Split(value, ",")
		result := make([]string, 0, len(parts))
		for _, p := range parts {
			trimmed := strings.TrimSpace(p)
			if trimmed != "" {
				result = append(result, trimmed)
			}
		}
		if len(result) > 0 {
			return result
		}
	}
	return defaultValue
}

[gemini-code-assist]

Using disable for DB_SSL_MODE is insecure for production environments, as it allows for unencrypted database connections. It's good for local development, but you should add a comment strongly recommending the use of require or verify-full in production to prevent man-in-the-middle attacks.

DB_SSL_MODE=disable # Use 'require' or 'verify-full' in production

[gemini-code-assist]

The Go code example for createPost ignores multiple potential errors (from json.Marshal, http.Post, and json.NewDecoder). While this is example code, it sets a bad precedent for API consumers. The example should demonstrate proper error handling to be more robust and educational.

func createPost(post Post) (*Post, error) {
    data, err := json.Marshal(post)
    if err != nil {
        return nil, err
    }
    resp, err := http.Post(baseURL+"/posts", "application/json", bytes.NewBuffer(data))
    if err != nil {
        return nil, err
    }
    defer resp.Body.Close()

    if resp.StatusCode != http.StatusCreated {
        return nil, fmt.Errorf("bad status: %s", resp.Status)
    }

    var result struct {
        Data Post `json:"data"`
    }
    if err := json.NewDecoder(resp.Body).Decode(&result); err != nil {
        return nil, err
    }
    return &result.Data, nil
}