nielsperetzke
/
healthchecks


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								{% block title %}Documentation - healthchecks.io{% endblock %}


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								<div class="row"><div class="col-sm-12">


								<h2>Summary</h2>

								<p>

								Each check you create in <a href="{% url 'hc-index' %}">My Checks</a>

								page has an unique "ping" URL. Whenever you access this URL,

								the "Last Ping" value of corresponding check is updated.

								</p>

								<p>When a certain amount of time passes since last received ping, the

								check is considered "late", and Health Checks sends an email alert.

								It is all very simple, really.</p>


								<h2>Executing a Ping</h2>

								<p>

								    At the end of your batch job, add a bit of code to request

								    your ping URL.

								</p>

								<ul>

								    <li>HTTP and HTTPS protocols both are fine</li>

								    <li>Request method can be GET, POST or HEAD</li>

								    <li>Both IPv4 and IPv6 work</li>

								    <li>It does not matter what request headers you send</li>

								    <li>You can leave request body empty or put anything in it, it's all good</li>

								</ul>


								<p>The response will have status code "200 OK" and response body will be a

								short and simple string "OK".</p>


								<p>

								    Here are examples of executing pings from different environments.

								</p>


								<h3>Crontab</h3>


								<p>

								When using cron, probably the easiest is to append a <code>curl</code>

								or <code>wget</code> call after your command. The scheduled time comes,

								and your command runs. After it completes, the healthchecks.io check

								gets pinged.

								</p>


								{% include "front/snippets/crontab.html" %}


								<p>With this simple modification, you monitor several failure

								scenarios:</p>


								<ul>

								    <li>The whole machine has stopped working (power outage, janitor stumbles on wires, VPS provider problems, etc.) </li>

								    <li>cron daemon is not running, or has invalid configuration</li>

								    <li>cron does start your task, but the task exits with non-zero exit code</li>

								</ul>


								<p>Either way, when your task doesn't finish successfully, you will soon

								know about it.</p>


								<h3>Bash or a shell script</h3>


								<p>Both <code>curl</code> and <code>wget</code> examples accomplish the same

								thing: they fire off a HTTP GET method.</p>


								<p>

								    If using <code>curl</code>, make sure it is installed on your target system.

								    Ubuntu, for example, does not have curl installed out of the box.

								</p>


								{% include "front/snippets/bash.html" %}


								<h3>Python</h3>

								{% include "front/snippets/python.html" %}


								<h3>Node</h3>

								{% include "front/snippets/node.html" %}


								<h3>PHP</h3>

								{% include "front/snippets/php.html" %}


								<h3>Browser</h3>

								<p>

								    healthchecks.io includes <code>Access-Control-Allow-Origin:*</code>

								    CORS header in its ping responses, so cross-domain AJAX requests

								    should work.

								</p>

								{% include "front/snippets/browser.html" %}


								<h3>Email</h3>

								<p>

								    As an alternative to HTTP/HTTPS requests,

								    you can "ping" this check by sending an

								    email message to <a href="mailto:{{ check.email }}">{{ check.email }}</a>

								</p>

								<p>

								    This is useful for end-to-end testing weekly email delivery.

								</p>

								<p>

								    An example scenario: you have a cron job which runs weekly and

								    sends weekly email reports to a list of e-mail addresses. You have already

								    set up a check to get alerted when your cron job fails to run.

								    But what you ultimately want to check is your emails <em>get sent and

								    get delivered</em>.

								</p>

								<p>

								    The solution: set up another check, and add its

								    @hchk.io address to your list of recipient email addresses. Set its

								    Period to 1 week. As long as your weekly email script runs correctly,

								    the check will be regularly pinged and will stay up.

								</p>


								<h2>When Alerts Are Sent</h2>

								<p>

								    Each check has a configurable <strong>Period</strong> parameter, with the default value of one day.

								    For periodic tasks, this is the expected time gap between two runs.

								</p>

								<p>

								    Additionally, each check has a <strong>Grace</strong> parameter, with default value of one hour.

								    You can use this parameter to account for run time variance of tasks.

								    For example, if a backup task completes in 50 seconds one day, and

								    completes in 60 seconds the following day, you might not want to get

								    alerted because the backups are 10 seconds late.

								</p>

								<p>Each check can be in one of the following states:</p>


								<table class="table">

								    <tr>

								        <td>

								            <span class="glyphicon glyphicon-question-sign new"></span>

								        </td>

								        <td>

								            <strong>New.</strong>

								            A check that has been created, but has not received any pings yet.

								        </td>

								    </tr>

								    <tr>

								        <td>

								            <span class="glyphicon glyphicon-ok-sign up"></span>

								        </td>

								        <td>

								            <strong>Up.</strong>

								            Time since last ping has not exceeded <strong>Period</strong>.

								        </td>

								    </tr>

								    <tr>

								        <td>

								            <span class="glyphicon glyphicon-exclamation-sign grace"></span>

								        </td>

								        <td>

								            <strong>Late.</strong>

								            Time since last ping has exceeded <strong>Period</strong>,

								            but has not yet exceeded <strong>Period</strong> + <strong>Grace</strong>.

								        </td>

								    </tr>

								    <tr>

								        <td>

								            <span class="glyphicon glyphicon-exclamation-sign down"></span>

								        </td>

								        <td>

								            <strong>Down.</strong>

								            Time since last ping has exceeded <strong>Period</strong> + <strong>Grace</strong>.

								            When check goes from "Late" to "Down", healthchecks.io

								            sends you an alert.

								        </td>

								    </tr>

								</table>


								</div></div>

								{% endblock %}