Claude Code
integration
Docker Compose Services Fail to Connect Due to Wrong Names
Your Docker Compose setup generated by Claude Code has services that fail to connect to each other. The application container can't reach the database, the backend can't connect to Redis, or the worker can't find the message broker. Everything works when running services individually but fails in Docker Compose.
Docker Compose creates a network where services can reach each other by their service name. When the application code uses 'localhost' or hardcoded IPs instead of service names, or when service names in docker-compose.yml don't match what the application expects, connections fail.
This is especially frustrating because the error messages often just say 'connection refused' or 'host not found' without indicating that the issue is a name mismatch.
Error Messages You Might See
Error: connect ECONNREFUSED 127.0.0.1:5432
psql: could not connect to server: Connection refused
redis.exceptions.ConnectionError: Error connecting to redis:6379
getaddrinfo ENOTFOUND database
Name or service not known
Common Causes
- Using localhost instead of service name — Application code connects to localhost:5432 but the database is in a separate container reachable by its service name
- Service name mismatch — docker-compose.yml defines the service as 'postgres' but the app config references 'db' or 'database'
- Missing depends_on — The app container starts before the database is ready to accept connections
- Wrong port mapping confusion — Using the host-mapped port (5433) instead of the container's internal port (5432)
- Custom network not shared — Services in different docker-compose files or custom networks can't see each other
How to Fix It
- Replace localhost with service names — Change database URLs from localhost:5432 to postgres:5432 (matching the service name in docker-compose.yml)
- Use environment variables for hostnames — Define DB_HOST, REDIS_HOST as environment variables in docker-compose.yml pointing to the correct service names
- Add proper health checks — Use healthcheck in docker-compose.yml and depends_on with condition: service_healthy to wait for dependencies
- Use internal container ports — Between containers, always use the internal port (5432), not the host-mapped port (5433:5432)
- Verify with docker compose exec — Shell into a container and try to ping or connect to the service name to debug networking
Real developers can help you.
Krishna Sai Kuncha
Experienced Professional Full stack Developer with 8+ years of experience across react, python, js, ts, golang and react-native. Developed inhouse websearch tooling for AI before websearch was solved : )
Sage Fulcher
Hey I'm Sage! Im a Boston area software engineer who grew up in South Florida. Ive worked at a ton of cool places like a telehealth kidney care startup that took part in a billion dollar merger (Cricket health/Interwell health), a boutique design agency where I got to work on a ton of exciting startups including a photography education app, a collegiate Esports league and more (Philosophie), a data analytics as a service startup in Cambridge (MA) as well as at Phillips and MIT Lincoln Lab where I designed and developed novel network security visualizations and analytics. I've been writing code and furiously devoted to using computers to make people’s lives easier for about 17 years. My degree is in making computers make pretty lights and sounds. Outside of work I love hip hop, the Celtics, professional wrestling, magic the gathering, photography, drumming, and guitars (both making and playing them)
BurnHavoc
Been around fixing other peoples code for 20 years.
Taufan
I’m a product-focused engineer and tech leader who builds scalable systems and turns ideas into production-ready platforms.
Over the past years, I’ve worked across startups and fast-moving teams, leading backend architecture, improving system reliability, and shipping products used by thousands of users. My strength is not just writing code — but connecting product vision, technical execution, and business impact.
Rudra Bhikadiya
I build and fix web apps across Next.js, Node.js, and DBs.
Comfortable jumping into messy code, broken APIs, and mysterious bugs.
If your project works in theory but not in reality, I help close that gap.
Richard McSorley
Full-Stack Software Engineer with 8+ years building high-performance applications for enterprise clients. Shipped production systems at Walmart (4,000+ stores), Cigna (20M+ users), and Arkansas Blue Cross. 5 patents in retail/supply chain tech. Currently focused on AI integrations, automation tools, and TypeScript-first architectures.
Basel Issmail
’m a Senior Full-Stack Developer and Tech Lead with experience designing and building scalable web platforms. I work across the full development lifecycle, from translating business requirements into technical architecture to delivering reliable production systems.
My work focuses on modern web technologies, including TypeScript, Angular, Node.js, and cloud-based architectures. I enjoy solving complex technical problems and helping teams turn product ideas and prototypes into working platforms that can grow and scale.
In addition to development, I often collaborate closely with product managers, business analysts, designers, and QA teams to ensure that solutions align with both technical and business goals.
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Mehdi Ben Haddou
- Founder of Chessigma (1M+ users) & many small projects
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Jacek Rozanski
Senior PHP/Symfony developer and DevOps engineer with 20+ years of professional experience, running opcode.pl (web development agency, est. 2004).
Day job: I'm the sole backend developer at merketing company where I own and maintain 11 PHP/Symfony microservices on AWS (ECS Fargate, RDS, S3, CloudFront), handle the full CI/CD pipeline (Bitbucket Pipelines, Docker), and manage monitoring with Sentry and CloudWatch. These services handle high request volumes in production every month.
What I bring to AI-built apps:
- I audit and fix security issues (OWASP methodology), performance bottlenecks, and architectural problems in codebases generated by Cursor, Claude Code, Lovable, Bolt, and v0
- I refactor AI-generated prototypes into production-grade applications with proper error handling, testing, and clean architecture (SOLID, DDD, hexagonal architecture)
- I set up the infrastructure AI tools don't touch: AWS hosting, CI/CD pipelines, automated deployments, database optimization, monitoring, and alerting
- I integrate external services: payment providers, email systems, partner APIs, SSO/auth
Tech stack: PHP 8.x, Symfony, React, Next.js, PostgreSQL, MySQL, Docker, AWS (ECS, RDS, S3, SQS/SNS, CloudFront), Terraform, Supabase. I also use AI tools daily (Claude Code, Cursor) in my own workflow, so I understand both the strengths and the gaps in AI-generated code.
Based in Poland (CET timezone). Available for async work and calls during EU/US business hours.
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Get HelpFrequently Asked Questions
Why can't my app container connect to the database using localhost?
In Docker Compose, each service runs in its own container with its own network namespace. localhost refers to the container itself, not other containers. Use the service name defined in docker-compose.yml (e.g., 'postgres') as the hostname.
How do I wait for the database to be ready before starting my app?
Use depends_on with a health check. Define a healthcheck on the database service (e.g., pg_isready) and set depends_on: postgres: condition: service_healthy on your app service.