Wait for service(s) to be available before executing a command.
wait-for-it is a script that will wait on the availability of one or more TCP services (i.e. host:port) before executing a user-defined command.
It is useful for synchronizing the spin-up of interdependent services, such as linked docker containers.
Check out the wait-for-it docs
$ pip install wait-for-it
Usage: wait-for-it [OPTIONS] [COMMANDS]...
Wait for service(s) to be available before executing a command.
Options:
-h, --help Show this message and exit.
-v, --version Show the version and exit.
-q, --quiet Do not output any status messages
-s, --service host:port Services to test, in the format host:port
-t, --timeout seconds Timeout in seconds, 0 for no timeout [default: 15]
Test to see if we can access port 80 on www.google.com, and if it is available, echo the message google is up:
$ wait-for-it \
--service www.google.com:80 \
-- echo "google is up"waiting 15 seconds for www.google.com:80
www.google.com:80 is available after 0 seconds
google is up
You can set your own timeout with the -t or --timeout option. Setting the timeout value to 0 will disable the timeout:
$ wait-for-it \
--service www.google.com:80 \
--timeout 0 \
-- echo "google is up"waiting for www.google.com:80 without a timeout
www.google.com:80 is available after 0 seconds
google is up
Multiple services can be tested by adding additional -s or --service options:
$ wait-for-it \
--service www.google.com:80 \
--service www.bing.com:80 \
--service www.duckduckgo.com:80 \
-- echo "google, bing, and duckduckgo are up"waiting 15 seconds for www.google.com:80
www.google.com:80 is available after 0 seconds
waiting 15 seconds for www.bing.com:80
www.bing.com:80 is available after 0 seconds
waiting 15 seconds for www.duckduckgo.com:80
www.duckduckgo.com:80 is available after 0 seconds
google, bing, and duckduckgo are up
Status message output can be suppressed with the -q or --quiet option:
$ wait-for-it \
--quiet \
--service www.google.com:80 \
-- echo "google is up"google is up
MIT © Travis Clarke