Overview#

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

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

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: 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 ...

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