A tool to wait for services and execute command. Useful for Docker containers that depend on slow to start services (like almost everything).


Keywords
wait, port, service, docker, unix, domain, socket, tcp, waiter, holdup, hold-up, dockerize, healthcheck, http, python, wait-for-it
License
BSD-2-Clause
Install
pip install holdup==1.0.0

Documentation

Overview

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A tool to wait for services and execute command. Useful for Docker containers that depend on slow to start services (like almost everything).

  • Free software: BSD 2-Clause License

Installation

Currently holdup is only published to PyPI and hub.docker.com.

To install from PyPI:

pip install holdup

It has no dependencies except the optional PostgreSQL check support, which you'd install with:

pip install 'holdup[pg]'

You can also install the in-development version with:

pip install https://github.com/ionelmc/python-holdup/archive/master.zip

Alternate installation (Docker image)

Example:

docker run --rm ionelmc/holdup tcp://foobar:1234

Note that this will have some limitations:

  • executing the command is pretty pointless because holdup will run in its own container
  • you'll probably need extra network configuration to be able to access services
  • you won't be able to use docker run inside a container without exposing a docker daemon in said container

Usage

usage: holdup [-h] [-t SECONDS] [-T SECONDS] [-i SECONDS] [-n] service [service ...] [-- command [arg [arg ...]]]

Wait for services to be ready and optionally exec command.

positional arguments:
service
A service to wait for. Supported protocols: "tcp://host:port/", "path:///path/to/something", "unix:///path/to/domain.sock", "eval://expr", "pg://user:password@host:port/dbname" ("postgres" and "postgresql" also allowed), "http://urn", "https://urn", "https+insecure://urn" (status 200 expected for http*). Join protocols with a comma to make holdup exit at the first passing one, eg: "tcp://host:1,host:2" or "tcp://host:1,tcp://host:2" are equivalent and mean any that pass.
command
An optional command to exec.
optional arguments:
-h, --help show this help message and exit
-t SECONDS, --timeout SECONDS
  Time to wait for services to be ready. Default: 60.0
-T SECONDS, --check-timeout SECONDS
  Time to wait for a single check. Default: 1.0
-i SECONDS, --interval SECONDS
  How often to check. Default: 0.2
-v, --verbose Verbose mode.
--verbose-passwords
  Disable PostgreSQL/HTTP password masking.
-n, --no-abort Ignore failed services. This makes holdup return 0 exit code regardless of services actually responding.
--insecure Disable SSL Certificate verification for HTTPS services.
--version display the version of the holdup package and its location, then exit.

Example:

holdup tcp://foobar:1234 -- django-admin ...

Documentation

https://python-holdup.readthedocs.io/

Development

To run all the tests run:

tox

Note, to combine the coverage data from all the tox environments run:

Windows
set PYTEST_ADDOPTS=--cov-append
tox
Other
PYTEST_ADDOPTS=--cov-append tox