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https://github.com/jeffbski/wait-on

wait-on is a cross-platform command line utility and Node.js API which will wait for files, ports, sockets, and http(s) resources to become available
https://github.com/jeffbski/wait-on

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wait-on is a cross-platform command line utility and Node.js API which will wait for files, ports, sockets, and http(s) resources to become available

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# wait-on - wait for files, ports, sockets, http(s) resources



wait-on is a cross-platform command line utility which will wait for files, ports, sockets, and http(s) resources to become available (or not available using reverse mode). Functionality is also available via a Node.js API. Cross-platform - runs everywhere Node.js runs (linux, unix, mac OS X, windows)



wait-on will wait for period of time for a file to stop growing before triggering availability which is good for monitoring files that are being built. Likewise wait-on will wait for period of time for other resources to remain available before triggering success.



For http(s) resources wait-on will check that the requests are returning 2XX (success) to HEAD or GET requests (after following any redirects).



wait-on can also be used in reverse mode which waits for resources to NOT be available. This is useful in waiting for services to shutdown before continuing. (Thanks @skarbovskiy for adding this feature)



[![CI](https://github.com/jeffbski/wait-on/actions/workflows/node.js.yml/badge.svg)](https://github.com/jeffbski/wait-on/actions/workflows/node.js.yml)



## Installation



Latest wait-on version 7+ requires Node.js 12+

wait-on versions 4-6 requires Node.js 10+



(Node.js v8 users can use [email protected], v4 users can still use [email protected], and older Node.js

engines, use [email protected])



```bash

npm install wait-on # local version

OR

npm install -g wait-on # global version

```



## Usage



Use from command line or using Node.js programmatic API.



### CLI Usage



Assuming NEXT_CMD is the command to run when resources are available, then wait-on will wait and then exit with a successful exit code (0) once all resources are available, causing NEXT_CMD to be run.



wait-on can also be used in reverse mode, which waits for resources to NOT be available. This is useful in waiting for services to shutdown before continuing. (Thanks @skarbovskiy for adding)



If wait-on is interrupted before all resources are available, it will exit with a non-zero exit code and thus NEXT_CMD will not be run.



```bash

wait-on file1 && NEXT_CMD # wait for file1, then exec NEXT_CMD

wait-on f1 f2 && NEXT_CMD # wait for both f1 and f2, the exec NEXT_CMD

wait-on http://localhost:8000/foo && NEXT_CMD # wait for http 2XX HEAD

wait-on https://myserver/foo && NEXT_CMD # wait for https 2XX HEAD

wait-on http-get://localhost:8000/foo && NEXT_CMD # wait for http 2XX GET

wait-on https-get://myserver/foo && NEXT_CMD # wait for https 2XX GET

wait-on tcp:4000 && NEXT_CMD # wait for service to listen on a TCP port

wait-on socket:/path/mysock # wait for service to listen on domain socket

wait-on http://unix:/var/SOCKPATH:http://server/a/foo # wait for http HEAD on domain socket

wait-on http-get://unix:/var/SOCKPATH:http://server/a/foo # wait for http GET on domain socket

```



```

Usage: wait-on {OPTIONS} resource [...resource]



Description:



     wait-on is a command line utility which will wait for files, ports,

     sockets, and http(s) resources to become available (or not available

     using reverse flag). Exits with  success code (0) when all resources

     are ready. Non-zero exit code if interrupted or timed out.



     Options may also be specified in a config file (js or json). For

     example --config configFile.js would result in configFile.js being

     required and the resulting object will be merged with any

     command line options before wait-on is called. See exampleConfig.js



     In shell combine with && to conditionally run another command

     once resources are available. ex: wait-on f1 && NEXT_CMD



     resources types are defined by their prefix, if no prefix is

     present, the resource is assumed to be of type 'file'. Resources

     can also be provided in the config file.



     resource prefixes are:



       file:      - regular file (also default type). ex: file:/path/to/file

       http:      - HTTP HEAD returns 2XX response. ex: http://m.com:90/foo

       https:     - HTTPS HEAD returns 2XX response. ex: https://my/bar

       http-get:  - HTTP GET returns 2XX response. ex: http://m.com:90/foo

       https-get: - HTTPS GET returns 2XX response. ex: https://my/bar

       tcp:       - TCP port is listening. ex: 1.2.3.4:9000 or foo.com:700

       socket:    - Domain Socket is listening. ex: socket:/path/to/sock

                    For http over socket, use http://unix:SOCK_PATH:URL_PATH

                    like http://unix:/path/to/sock:http://server/foo/bar or

                         http-get://unix:/path/to/sock:http://server/foo/bar



Standard Options:



 -c, --config



  js or json config file, useful for http(s) options and resources



 -d, --delay



  Initial delay before checking for resources in ms, default 0



 --httpTimeout



  Maximum time in ms to wait for an HTTP HEAD/GET request, default 0

  which results in using the OS default



-i, --interval



  Interval to poll resources in ms, default 250ms



 -l, --log



  Log resources begin waited on and when complete or errored



 -r, --reverse



  Reverse operation, wait for resources to NOT be available



 -s, --simultaneous



  Simultaneous / Concurrent connections to a resource, default Infinity

  Setting this to 1 would delay new requests until previous one has completed.

  Used to limit the number of connections attempted to a resource at a time.



 -t, --timeout



  Maximum time in ms to wait before exiting with failure (1) code,

  default Infinity

  Use postfix 'ms', 's', 'm' or 'h' to change the unit.



  --tcpTimeout



  Maximum time in ms for tcp connect, default 300ms

  Use postfix 'ms', 's', 'm' or 'h' to change the unit.



  --httpTimeout



  Maximum time to wait for the HTTP request, default Infinity

  Use postfix 'ms', 's', 'm' or 'h' to change the unit.



 -v, --verbose



  Enable debug output to stdout



 -w, --window



  Stability window, the time in ms defining the window of time that

  resource needs to have not changed (file size or availability) before

  signalling success, default 750ms. If less than interval, it will be

  reset to the value of interval. This is only used for files, other

  resources are considered available on first detection.



 -h, --help



  Show this message

```



### Node.js API usage



```javascript

var waitOn = require('wait-on');

var opts = {

  resources: [

    'file1',

    'http://foo.com:8000/bar',

    'https://my.com/cat',

    'http-get://foo.com:8000/bar',

    'https-get://my.com/cat',

    'tcp:foo.com:8000',

    'socket:/my/sock',

    'http://unix:/my/sock:http://server/my/url',

    'http-get://unix:/my/sock:http://server/my/url'

  ],

  delay: 1000, // initial delay in ms, default 0

  interval: 100, // poll interval in ms, default 250ms

  simultaneous: 1, // limit to 1 connection per resource at a time

  timeout: 30000, // timeout in ms, default Infinity

  tcpTimeout: 1000, // tcp timeout in ms, default 300ms

  window: 1000, // stabilization time in ms, default 750ms



  // http options

  ca: [

    /* strings or binaries */

  ],

  cert: [

    /* strings or binaries */

  ],

  key: [

    /* strings or binaries */

  ],

  passphrase: 'yourpassphrase',

  proxy: false /* OR proxy config as defined in axios.

  If not set axios detects proxy from env vars http_proxy and https_proxy

  https://github.com/axios/axios#config-defaults

  {

    host: '127.0.0.1',

    port: 9000,

    auth: {

      username: 'mikeymike',

      password: 'rapunz3l'

    }

  } */,

  auth: {

    user: 'theuser', // or username

    pass: 'thepassword' // or password

  },

  strictSSL: false,

  followRedirect: true,

  headers: {

    'x-custom': 'headers'

  },

  validateStatus: function (status) {

    return status >= 200 && status < 300; // default if not provided

  }

};



// Usage with callback function

waitOn(opts, function (err) {

  if (err) {

    return handleError(err);

  }

  // once here, all resources are available

});



// Usage with promises

waitOn(opts)

  .then(function () {

    // once here, all resources are available

  })

  .catch(function (err) {

    handleError(err);

  });



// Usage with async await

try {

  await waitOn(opts);

  // once here, all resources are available

} catch (err) {

  handleError(err);

}

```



waitOn(opts, [cb]) - function which triggers resource checks



- opts.resources - array of string resources to wait for. prefix determines the type of resource with the default type of `file:`

- opts.delay - optional initial delay in ms, default 0

- opts.interval - optional poll resource interval in ms, default 250ms

- opts.log - optional flag which outputs to stdout, remaining resources waited on and when complete or errored

- opts.resources - optional array of string resources to wait for if none are specified via command line

- opts.reverse - optional flag to reverse operation so checks are for resources being NOT available, default false

- opts.simultaneous - optional count to limit concurrent connections per resource at a time, setting to 1 waits for previous connection to succeed, fail, or timeout before sending another, default infinity

- opts.timeout - optional timeout in ms, default Infinity. Aborts with error.

- opts.tcpTimeout - optional tcp timeout in ms, default 300ms

- opts.verbose - optional flag which outputs debug output, default false

- opts.window - optional stabilization time in ms, default 750ms. Waits this amount of time for file sizes to stabilize or other resource availability to remain unchanged.

- http(s) specific options, see https://nodejs.org/api/tls.html#tls_tls_connect_options_callback for specific details



  - opts.ca: [ /* strings or binaries */ ],

  - opts.cert: [ /* strings or binaries */ ],

  - opts.key: [ /* strings or binaries */ ],

  - opts.passphrase: 'yourpassphrase',

  - opts.proxy: undefined, false, or object as defined in axios. Default is undefined. If not set axios detects proxy from env vars http_proxy and https_proxy. https://github.com/axios/axios#config-defaults



```js

  // example proxy object

  {

    host: '127.0.0.1',

    port: 9000,

    auth: {

      username: 'mikeymike',

      password: 'rapunz3l'

    }

  }

```



- opts.auth: { user, pass }

- opts.strictSSL: false,

- opts.followRedirect: false, // defaults to true

- opts.headers: { 'x-custom': 'headers' },



- cb(err) - if err is provided then, resource checks did not succeed



## Goals



- simple command line utility and Node.js API for waiting for resources

- wait for files to stabilize

- wait for http(s) resources to return 2XX in response to HEAD request

- wait for http(s) resources to return 2XX in response to GET request

- wait for services to be listening on tcp ports

- wait for services to be listening on unix domain sockets

- configurable initial delay, poll interval, stabilization window, timeout

- command line utility returns success code (0) when resources are availble

- command line utility that can also wait for resources to not be available using reverse flag. This is useful for waiting for services to shutdown before continuing.

- cross platform - runs anywhere Node.js runs (linux, unix, mac OS X, windows)



## Why



I frequently need to wait on build tasks to complete or services to be available before starting next command, so this project makes that easier and is portable to everywhere Node.js runs.



## Get involved



If you have input or ideas or would like to get involved, you may:



- contact me via twitter @jeffbski - 

- open an issue on github to begin a discussion - 

- fork the repo and send a pull request (ideally with tests) - 



## License



- [MIT license](http://github.com/jeffbski/wait-on/raw/master/LICENSE)