wait-for-it

A Golang package to wait on the availability of a TCP host and port.
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Table of Contents

• About the Project
  • Built With
• Getting Started
  • Prerequisites
  • Installation
• Usage
• Roadmap
• Contributing
• License
• Contributors

About The Project

This package is adapted from vishnubob/wait-for-it, a popular project used to wait for TCP connections until a service is up. This is commonly used in docker-compose files to make one service wait for another, for example, to make a web server wait for a mysql database.

Since vishnubob/wait-for-it is a bash script, it does not work directly with minimal containers like scratch, which are commonly used to run binaries.

With the help of this package, you can generate a binary, which can run inside minimal Docker containers and wait for a TCP connection such as a mysql database. You can find an example here: csivitu/bl0b.

Built With

• Go

Getting Started

A amd64 (64-bit) executables for linux, darwin, and windows are available in the GitHub releases.

If you want to build a binary for a different Operating System / Architecture, you can follow the procedure below.

Prerequisites

The only prerequisite is golang which you can get here.

• go

Installation

1. Get the package using go install.

go install github.com/roerohan/wait-for-it

Alternatively, you can follow these steps:

1. Clone the repository.

git clone https://github.com/roerohan/wait-for-it

2. Build a go binary from source.

cd wait-for-it
go build -o ./bin/wait-for-it

3. Use the binary inside the bin folder.

./bin/wait-for-it google.com:80 -- echo "It works\!"

Usage

The usage is similar to vishnubob/wait-for-it.

Use wait-for-it -h to display the following list.

Usage of wait-for-it:
  -q    Quiet, don't output any status messages
  -s    Only execute subcommand if the test succeeds
  -t int
        Timeout in seconds, zero for no timeout (default 15)
  -w host:port
        Services to be waiting for, in the form host:port

You can run any executable after passing --, like in the examples below.

Examples:

1. Waiting for multiple services in parallel.

wait-for-it -w google.com:80 -w localhost:27017 -t 30 -- echo "Waiting for 30 seconds for google.com:80 and localhost:27017"

2. Strict mode will not execute the subcommand only if TCP connection was successful.

$ wait-for-it -w abcd:80 -s -t 5 -- echo "Done\!"
wait-for-it: waiting 5 seconds for abcd:80
wait-for-it: timeout occured after waiting for 5 seconds
wait-for-it: strict mode, refusing to execute subprocess

Roadmap

See the open issues for a list of proposed features (and known issues).

Contributing

Contributions are what make the open source community such an amazing place to be learn, inspire, and create. Any contributions you make are greatly appreciated.

1. Fork the Project
2. Create your Feature Branch (git checkout -b feature/AmazingFeature)
3. Commit your Changes (git commit -m 'feat: Add some AmazingFeature')
4. Push to the Branch (git push origin feature/AmazingFeature)
5. Open a Pull Request

You are requested to follow the contribution guidelines specified in CONTRIBUTING.md while contributing to the project 😄.

License

Distributed under the MIT License. See LICENSE for more information.