wait-for

A simple CLI to wait for a service to be available before executing a command.

wait-for is a Rust rewrite of the popular eficode/wait-for shell script. It provides a reliable way to wait for network services to become available, which is especially useful in Docker Compose setups and CI/CD pipelines.

Features

• Self-contained: No external dependencies like netcat or wget required
• Cross-platform: Single binary for Linux, macOS, and Windows
• Fast: Written in Rust for optimal performance
• Docker-friendly: Perfect for container orchestration scenarios
• CI/CD ready: Seamlessly integrates with any build pipeline

Installation

Using Cargo

cargo install wait-for-rs

Download Binary

Download pre-compiled binaries from the GitHub Releases page.

Docker Usage

# Copy the binary into your Docker image
COPY wait-for /usr/local/bin/wait-for
RUN chmod +x /usr/local/bin/wait-for

# Use it in your entrypoint
ENTRYPOINT ["wait-for", "db:5432", "--", "./start-app.sh"]

Usage

Basic Examples

Wait for a TCP service:

wait-for db:5432

Wait for an HTTP service:

wait-for https://api.example.com/health

Execute a command after service is ready:

wait-for redis:6379 -- ./run-tests.sh

With custom timeout:

wait-for -t 30 postgres:5432 -- python manage.py migrate

Silent mode:

wait-for -q api:8080 -- curl http://api:8080/status

Docker Compose Example

version: "3.8"
services:
  db:
    image: postgres:13
    environment:
      POSTGRES_PASSWORD: password

  web:
    image: myapp:latest
    depends_on:
      - db
    command: ["wait-for", "db:5432", "--", "python", "manage.py", "runserver"]

CI/CD Pipeline Examples

GitHub Actions

- name: Wait for test database
  run: wait-for localhost:5432 -- npm run test

GitLab CI

test:
  script:
    - wait-for redis:6379 -- pytest tests/

Command Line Reference

A simple CLI to wait for a service to be available before executing a command

Usage: wait-for [OPTIONS] <TARGET> [COMMAND]...

Arguments:
  <TARGET>      Service to wait for (host:port or URL)
  [COMMAND]...  Command to execute after successful wait

Options:
  -t, --timeout <TIMEOUT>  Timeout in seconds (0 for no timeout) [default: 15]
  -q, --quiet              Quiet mode - suppress output
  -h, --help               Print help
  -V, --version            Print version

Target Formats

• TCP: host:port (e.g., localhost:3306, redis:6379)
• HTTP/HTTPS: Full URL (e.g., https://api.example.com/health, http://localhost:8080/ready)

Exit Codes

• 0: Service is available (and command executed successfully if provided)
• 1: Timeout reached or connection failed
• Other: Exit code of the executed command (if provided)

Examples by Use Case

Database Initialization

# Wait for PostgreSQL and run migrations
wait-for postgres:5432 -- python manage.py migrate

# Wait for MySQL and seed data
wait-for mysql:3306 -- npm run db:seed

Microservices

# Wait for API service before running tests
wait-for api:8080 -- npm run integration-tests

# Chain multiple service dependencies
wait-for redis:6379 && wait-for postgres:5432 -- ./start-worker.sh

Health Checks

# Wait for HTTP health endpoint
wait-for https://api.example.com/health -- curl -f https://api.example.com/data

# Custom timeout for slow services
wait-for -t 60 elasticsearch:9200 -- python index_data.py

Building from Source

git clone https://github.com/poi2/wait-for-rs.git
cd wait-for-rs
cargo build --release

The binary will be available at target/release/wait-for.

Comparison with Original wait-for

Contributing

Contributions are welcome! Please feel free to submit a Pull Request.

License

This project is dual-licensed under either:

• MIT License (LICENSE-MIT or http://opensource.org/licenses/MIT)
• Apache License, Version 2.0 (LICENSE-APACHE or http://www.apache.org/licenses/LICENSE-2.0)

at your option.

Acknowledgments

• Inspired by eficode/wait-for
• Built with clap for CLI parsing
• HTTP client powered by reqwest