attempt - a CLI for retrying fallible commands

attempt allows you to retry fallible commands with a delay.

How do I use it?

attempt [BACKOFF] [OPTIONS] [COMMAND]...

# Rerun database migrations if the server was not ready
attempt --retry-if-contains "server not ready" sqlx migrate

# Use an exponential backoff
attempt exponential --retry-if-contains "server not ready" sqlx migrate

What can I do with it?

• Wait for a service to start when you aren't restricted to bash
• Write robust scripts accessing resources which may become temporarily unavailable
• Bodge flaky programs into working

Key features

• Simple.
  • The featureset is small but flexible enough to covers most usecases.
  • The codebase can be audited in an afternoon.
• Robust.
  • It provides the tools you need to implement fault tolerance, like timeouts, jitter, and exponential backoff.
  • The test suite is extensive and contains both end-to-end and unit tests.
• Free forever.
  • The codebase is in the public domain.
  • All future versions will be released under the same license.

Documentation

• See the usage instructions to get a quick start
• The scripting guide has advice about using attempt in scripts
• Read the user manual for full documentation
• Run attempt --help for quick access to documentation
  • Note that you need to specify a strategy to see it's parameters, eg attempt exponential --help

Known issues

• attempt assumes that the child command's output will be UTF-8 encoded. If any output predicates are used on a program that outputs invalid UTF-8, attempt will crash.
• attempt --help will not reflect that the fixed strategy will be used if no strategy is specified.

Installation

Cargo:

cargo install attempt-cli

Homebrew:

brew install attempt-cli