`wait-for-it.sh` is a pure bash script that will wait on the availability of a host and TCP port. It is useful for synchronizing the spin-up of interdependent services, such as linked docker containers. Since it is a pure bash script, it does not have any external dependencies.
For example, let's test to see if we can access port 80 on www.google.com, and if it is available, echo the message `google is up`.
```
```sh
$ ./wait-for-it.sh www.google.com:80 -- echo "google is up"
wait-for-it.sh: waiting 15 seconds for www.google.com:80
wait-for-it.sh: www.google.com:80 is available after 0 seconds
@ -29,7 +29,7 @@ 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:
```
```sh
$ ./wait-for-it.sh -t 0 www.google.com:80 -- echo "google is up"
wait-for-it.sh: waiting for www.google.com:80 without a timeout
wait-for-it.sh: www.google.com:80 is available after 0 seconds
@ -38,7 +38,7 @@ google is up
The subcommand will be executed regardless if the service is up or not. If you wish to execute the subcommand only if the service is up, add the `--strict` argument. In this example, we will test port 81 on www.google.com which will fail:
```
```sh
$ ./wait-for-it.sh www.google.com:81 --timeout=1 --strict -- echo "google is up"
wait-for-it.sh: waiting 1 seconds for www.google.com:81
wait-for-it.sh: timeout occurred after waiting 1 seconds for www.google.com:81
If you don't want to execute a subcommand, leave off the `--` argument. This way, you can test the exit condition of `wait-for-it.sh` in your own scripts, and determine how to proceed:
```
```sh
$ ./wait-for-it.sh www.google.com:80
wait-for-it.sh: waiting 15 seconds for www.google.com:80
wait-for-it.sh: www.google.com:80 is available after 0 seconds
Christopher Fenner
4 years ago
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