is_ready

is_ready is a self-contained program designed to wait until multiple addresses become accessible. Its purpose is to coordinate the startup of interconnected services, such as Docker containers that rely on one another. This tool does not rely on any external dependencies and can be executed as a standalone binary.

Table of Contents

• Why
• Examples
• Installation & Usage
  • Use inside Docker
  • Use as a Docker container
• License

Why

There are alternative solutions like wait-for-it and wait-for. The key differentiating factor of is_ready compared to alternative solutions is its ability to wait for the availability of multiple addresses, not only one. Finally, unlike other options, is_ready stands out as a self-contained binary, eliminating the need for any external dependencies.

Examples

$ is_ready --help

Usage: is_ready [OPTIONS] --addr <ADDRESS> -- <COMMAND>...

Arguments:
  <COMMAND>...

Options:
  -t, --timeout <TIMEOUT>  [default: 30]
  -a, --addr <ADDRESS>
  -q, --quiet              Suppress output
  -h, --help               Print help
  -V, --version            Print version


$ is_ready \
    --timeout 10 \
    --addr github.com:80 \
    --addr google.com:80 \
    -- echo "The addresses are available"

Connected to google.com:80 successfully
Connected to github.com:80 successfully
The addresses are available

Installation & Usage

is_ready is optimized for running in a Docker container, and it is ideal to wait for the availability of other services such as databases, caches, or other services.

Use inside Docker

Example using the Docker Image:

# Set the version you want to download
ARG IS_READY_VERSION=1.0.2
FROM ghcr.io/stavrospanakakis/is_ready:$IS_READY_VERSION AS is_ready

FROM alpine:3.19

RUN apk add --no-cache curl

# Download the binary
COPY --from=is_ready /is_ready /usr/local/bin/is_ready

...
...

Example using curl:

FROM alpine:3.19

RUN apk add --no-cache curl

# Set the version you want to download
ENV IS_READY_VERSION=v1.0.2

# Download the binary
RUN curl -L https://github.com/Stavrospanakakis/is_ready/releases/download/${IS_READY_VERSION}/is_ready_${IS_READY_VERSION}_x86_64-unknown-linux-musl.tar.gz | tar xzf - -C /usr/local/bin

...
...

Example Docker Compose:

version: '3'
services:
  mysql:
    image: mysql:8.0
  
  app:
    build: .
    command: is_ready --timeout 10 --addr mysql:3306 -- echo "MySQL is ready"

Use as a Docker container

is_ready can be also used as a Docker container using the ghcr.io/stavrospanakakis/is_ready image from GitHub Container Registry.

$ VERSION=1.0.2
$ docker run --rm ghcr.io/stavrospanakakis/is_ready:$VERSION --version
is_ready 1.0.2

License

MIT