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# wait-for-it
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`wait-for-it.sh` is a pure bash script that will wait on the availability of a
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host and TCP port. It is useful for synchronizing the spin-up of
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interdependent services, such as linked docker containers. Since it is a pure
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bash script, it does not have any external dependencies.
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## Usage
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```text
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wait-for-it.sh host:port [-s] [-t timeout] [-- command args]
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-h HOST | --host=HOST Host or IP under test
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-p PORT | --port=PORT TCP port under test
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Alternatively, you specify the host and port as host:port
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-s | --strict Only execute subcommand if the test succeeds
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-q | --quiet Don't output any status messages
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-t TIMEOUT | --timeout=TIMEOUT
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Timeout in seconds, zero for no timeout
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-- COMMAND ARGS Execute command with args after the test finishes
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```
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## Examples
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For example, let's test to see if we can access port 80 on `www.google.com`,
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and if it is available, echo the message `google is up`.
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```text
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$ ./wait-for-it.sh www.google.com:80 -- echo "google is up"
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wait-for-it.sh: waiting 15 seconds for www.google.com:80
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wait-for-it.sh: www.google.com:80 is available after 0 seconds
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google is up
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```
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You can set your own timeout with the `-t` or `--timeout=` option. Setting
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the timeout value to 0 will disable the timeout:
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```text
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$ ./wait-for-it.sh -t 0 www.google.com:80 -- echo "google is up"
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wait-for-it.sh: waiting for www.google.com:80 without a timeout
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wait-for-it.sh: www.google.com:80 is available after 0 seconds
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google is up
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```
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The subcommand will be executed regardless if the service is up or not. If you
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wish to execute the subcommand only if the service is up, add the `--strict`
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argument. In this example, we will test port 81 on `www.google.com` which will
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fail:
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```text
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$ ./wait-for-it.sh www.google.com:81 --timeout=1 --strict -- echo "google is up"
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wait-for-it.sh: waiting 1 seconds for www.google.com:81
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wait-for-it.sh: timeout occurred after waiting 1 seconds for www.google.com:81
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wait-for-it.sh: strict mode, refusing to execute subprocess
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```
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If you don't want to execute a subcommand, leave off the `--` argument. This
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way, you can test the exit condition of `wait-for-it.sh` in your own scripts,
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and determine how to proceed:
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```text
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$ ./wait-for-it.sh www.google.com:80
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wait-for-it.sh: waiting 15 seconds for www.google.com:80
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wait-for-it.sh: www.google.com:80 is available after 0 seconds
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$ echo $?
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0
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$ ./wait-for-it.sh www.google.com:81
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wait-for-it.sh: waiting 15 seconds for www.google.com:81
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wait-for-it.sh: timeout occurred after waiting 15 seconds for www.google.com:81
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$ echo $?
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124
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```
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## Community
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*Debian*: There is a [Debian package](https://tracker.debian.org/pkg/wait-for-it).
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