Author: buildbot
Date: Tue Aug 13 13:11:19 2013
New Revision: 874462
Log:
Staging update by buildbot for sling
Modified:
websites/staging/sling/trunk/content/ (props changed)
websites/staging/sling/trunk/content/documentation/bundles/jconsole-hc.jpg
websites/staging/sling/trunk/content/documentation/bundles/sling-hc-plugin.jpg
websites/staging/sling/trunk/content/documentation/bundles/sling-health-check-tool.html
Propchange: websites/staging/sling/trunk/content/
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-1513104
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---
websites/staging/sling/trunk/content/documentation/bundles/sling-health-check-tool.html
(original)
+++
websites/staging/sling/trunk/content/documentation/bundles/sling-health-check-tool.html
Tue Aug 13 13:11:19 2013
@@ -85,76 +85,62 @@
<h1>Sling Health Check Tool</h1>
- <p>Based on extensible rules that check various system attributes, the
Sling Health Check Tool ("hc" in short form) is used to
-check the health of live Sling systems, based on various <em>system
attributes</em> that the rules check.</p>
-<div class="warning">
-This module is being extensively redesigned as part of SLING-2987 - the code
that is described here
-is available at
https://svn.apache.org/repos/asf/sling/tags/healthcheck-before-SLING-2987/ and
for now
-this page is out of sync with the current trunk code.
-</div>
-
-<p>The rules evaluation results are available in JSON format via HTTP
requests, as a Webconsole plugin
-and via JMX.</p>
+ <p>Based on simple <em>HealthCheck</em> OSGi services, the Sling Health
Check Tool ("hc" in short form) is used to
+check the health of live Sling systems, based on inputs like JMX MBean
attribute values, OSGi framework
+information, Sling requests status, etc.</p>
+<p>Health checks are easily extensible either by configuring the supplied
default <em>HealthCheck</em> services, or
+by implementing your own services. </p>
<p>Default rules are provided to check JMX MBeans, OSGi bundle states,
disabling of default Sling
accounts, JUnit tests results and the output of scripts written in any
language supported by Sling.</p>
-<p>Custom rules can be created by supplying <em>RuleBuilder</em> OSGi
services, see the <em>hc-sling</em> and <em>sling-demo</em> modules for
examples.</p>
<p>The source code of the hc modules is at <a
href="http://svn.apache.org/repos/asf/sling/trunk/contrib/extensions/healthcheck";>http://svn.apache.org/repos/asf/sling/trunk/contrib/extensions/healthcheck</a>.</p>
-<h2 id="example-rules">Example rules</h2>
-<p>A set of example rules is provided as <a
href="http://svn.apache.org/repos/asf/sling/trunk/contrib/extensions/healthcheck/sling-demo/src/main/resources/SLING-CONTENT/apps/hc/demo";>initial
content in the sling-demo module</a>.</p>
-<p>To test them, you need to add the required bundles to a Sling trunk
instance, as shown below, as the health check tool
-bundles are currently (July 2013) not included in the default Sling
launchpad.</p>
-<ol>
-<li>Start a standalone Sling instance from <em>launchpad/builder</em></li>
-<li>Optionally install the <em>org.apache.sling.junit.core</em> bundle,
version 1.0.8 or later, if you want to enable JUnit-based rules.</li>
-<li>Build the <em>contrib/extensions/healthcheck</em> modules.</li>
-<li>From that module, install the <em>org.apache.sling.hc.core</em> ,
<em>org.apache.sling.hc.rules</em> , <em>org.apache.sling.hc.sling</em> and
<em>org.apache.sling.hc.slingdemo</em> bundles.</li>
-<li>Open the health check webconsole at <em>/system/console/healthcheck</em>
and follow the instructions. The <em>org.apache.sling.hc.slingdemo</em> bundle
provides a set of example rules under <em>/apps/hc</em> , you can use that for
testing.</li>
-</ol>
-<p>You can also see the raw output of the rules execution servlet (as admin)
at <em>/apps/hc/demo.healthcheck.json</em>
-and the example rules content at <em>/apps/hc/demo.tidy.infinity.json</em>
.</p>
-<p>Rules can have a multi-value <em>tags</em> property that allows them to be
executed in groups. Entering <em>sling,bundles</em> as tags in the webconsole
-plugin form, or using them as selectors (
<em>/apps/hc/demo.healthcheck.bundles.sling.json</em> ) demonstrates this
feature.</p>
+<h2 id="whats-a-healthcheck">What's a HealthCheck ?</h2>
+<p>A <em>HealthCheck</em> is just an OSGi service that returns a
<em>Result</em>.</p>
+<p>The Result provides a <em>Status</em> (OK, WARN, CRITICAL etc.) and a
human-readable log which provides additional info, including optional DEBUG
messages
+that help troubleshooting. The Result log is not stricly tied to a logging
model, so HealthChecks are free to invent their own types of logging messages
+if needed. See the <code>org.apache.sling.hc.api.Result</code> class in the
for more details. </p>
+<p>HealthCheck services can be selected for execution based on their
<em>tags</em>. The <em>HealthCheckFilter</em> utility
+accepts positive and negative tag parameters, so that
<code>-security,sling</code> for example selects all HealthCheck
+having the <em>sling</em> tag but not the <em>security</em> tag. </p>
+<h2 id="executing-health-checks">Executing health checks</h2>
+<p>Besides executing them programatically, Health checks can be executed via a
webconsole plugin or via JMX,
+see below for more details.</p>
+<h2 id="default-healthcheck-services-and-samples">Default HealthCheck services
and samples</h2>
+<p>As of mid-August 2013, the <code>org.apache.sling.hc.samples</code> bundle
provides OSGi configurations that demonstrate the following HealthCheck
services:</p>
+<ul>
+<li><code>JmxAttributeHealthCheck</code> checks the value of a single JMX
attribute and supports ranges like <em>between 12 and 42</em>. </li>
+<li><code>SlingRequestStatusHealthCheck</code> checks the HTTP status of Sling
requests. </li>
+<li><code>ScriptableHealthCheck</code> evaluates an expression written in any
scripting language that Sling supports, and provides bindings to access JMX
attributes and OSGi bundles states. </li>
+<li><code>DefaultLoginsHealthCheck</code> can be used to verify that the
default Sling logins fail. </li>
+<li><code>CompositeHealthCheck</code> executes a set of HealthCheck selected
by tags, useful to get higher-level management views.</li>
+</ul>
+<h2 id="configuring-health-checks">Configuring health checks</h2>
+<p>Health check services are created via OSGi configurations.</p>
+<p>Here's a <code>ScriptableHealthCheck</code> example configuration provided
by the <code>org.apache.sling.hc.samples</code> bundle:</p>
+<p>PID = org.apache.sling.hc.ScriptableHealthCheck.1523a6db-12324
+ Factory PID = org.apache.sling.hc.ScriptableHealthCheck
+ hc.mbean.name = InactiveBundlesCheck
+ hc.name = No inactive bundles
+ hc.tags = [bundles, script]
+ expression = osgi.inactiveBundlesCount() == 0
+ language.extension = ecma</p>
+<p>Properties starting with the <code>hc.</code> prefix should be provided by
all HealthCheck services.</p>
<h2 id="webconsole-plugin">Webconsole plugin</h2>
-<p>As mentioned above, a webconsole plugin at
<em>/system/console/healthcheck</em> allows for executing health check rules,
optionally selected based on their
-tags and optionally showing only results from rules that have something to
report (as in "no news is good news").</p>
-<p>The screenshot below shows an example, as of svn revision 1490286.</p>
+<p>A webconsole plugin at <code>/system/console/healthcheck</code> allows for
executing health checks, optionally selected
+based on their tags.</p>
+<p>The DEBUG logs of health checks can optionally be displayed, and an option
allows for showing only health
+checks that have a non-OK status.</p>
+<p>The screenshot below shows an example, as of svn revision 1513462.</p>
<p><img alt="" src="sling-hc-plugin.jpg" /></p>
-<h2 id="jmx-interfaces">JMX interfaces</h2>
-<h3 id="accessing-and-combining-jmx-attributes-in-scripted-rules">Accessing
and combining JMX attributes in scripted rules</h3>
-<p>Although the basic <em>jmxbeans</em> rules give access to single JMX
attribute values in rules, a more powerful way to access
-JMX attributes is to use scripted rules, where mini-scripts can be written to
combine and check multiple values.</p>
-<p>The rule definition shown below, for example, checks two JMX attributes.
Such scripted rules can be written in any scripting language
-that Sling supports, selected by an extension (ecma, groovy etc.) specified in
the rule qualifier. </p>
-<div class="codehilite"><pre><span class="p">{</span>
- "<span class="n">sling</span><span class="p">:</span><span
class="n">resourceType</span>" <span class="p">:</span> "<span
class="n">sling</span><span class="o">/</span><span
class="n">healthcheck</span><span class="o">/</span><span
class="n">rules</span>"<span class="p">,</span>
- "<span class="n">namespace</span>"<span class="p">:</span>
"<span class="n">script</span>"<span class="p">,</span>
- "<span class="n">ruleName</span>"<span class="p">:</span>
"<span class="n">Example</span> <span class="n">javascript</span> <span
class="n">expression</span> <span class="n">that</span> <span
class="n">combines</span> <span class="n">two</span> <span class="n">JMX</span>
<span class="n">attributes</span>"<span class="p">,</span>
- "<span class="n">qualifier</span>"<span class="p">:</span>
"<span class="n">ecma</span>"<span class="p">,</span>
- "<span class="n">expression</span>"<span class="p">:</span>
- <span
class="s">'jmx.attribute("java.lang:type=ClassLoading",
"LoadedClassCount") > 100 </span>
-<span class="s"> &&
jmx.attribute("osgi.core:type=framework,version=1.5","FrameworkStartLevel")
> 1'</span><span class="p">,</span>
- "<span class="n">tags</span>" <span class="p">:</span> <span
class="p">[</span>"<span class="n">script</span>"<span
class="p">,</span>"<span class="n">javascript</span>"<span
class="p">,</span> "<span class="n">jmx</span>" <span
class="p">],</span>
- "<span class="n">jcr</span><span class="p">:</span><span
class="n">primaryType</span>"<span class="p">:</span> "<span
class="n">nt</span><span class="p">:</span><span
class="n">unstructured</span>"
-<span class="p">}</span>
-</pre></div>
-
-
-<h3 id="jmx-access-to-health-check-rules-results">JMX access to Health Check
Rules results</h3>
-<p>Creating <em>org.apache.sling.hc.sling.impl.RulesMBeans</em> OSGi
configurations causes the results of health
-check rules to be made available via JMX MBeans in the
<em>org.apache.sling.healthcheck</em> JMX tree.</p>
-<p>The slingdemo module provides an <a
href="http://svn.apache.org/repos/asf/sling/trunk/contrib/extensions/healthcheck/sling-demo/src/main/resources/SLING-CONTENT/apps/hc/install/org.apache.sling.hc.sling.impl.RulesMBeans-1.json";>example
configuration</a>, which is used in the screenshot below.</p>
-<p>To create such a configuration you need to specify the root path where rule
definitions are found in the
-repository, an optional MBean name that's used to name this set of rules below
the
-<em>org.apache.sling.healthcheck</em> JMX tree root, and an optional set of
rules tags to select which rules
-to include.</p>
-<p>Multiple <em>RulesMBeans</em> configurations can be used to provide various
views on the health check rules.
-This can cause a rule to appear in multiple places in the JMX tree, which is
not really a problem as the rule
-data is read-only.</p>
+<h2 id="jmx-access-to-health-checks">JMX access to health checks</h2>
+<p>A JMX MBean is created for each HealthCheck, which gives access to the
<code>Result</code> and the log, as shown
+on the screenshot below. </p>
+<p>The MBean name defaults to the <code>hc.name</code> service property of the
<em>HealthCheck</em>, but if an
+<code>hc.mbean.name</code> property is provided it is used instead. That
property can include a a slash
+(as in <code>composite/security</code>) to define the MBean service name,
which by default is <em>HealthCheck</em>.</p>
+<p>The example configurations of the <code>org.apache.sling.hc.samples</code>
bundle demonstrate the various features.</p>
<p><img alt="" src="jconsole-hc.jpg" /></p>
-<h2 id="known-issues">Known issues</h2>
-<p>See <a
href="https://issues.apache.org/jira/browse/SLING-2822";>SLING-2822</a> for
details.</p>
<div class="timestamp" style="margin-top: 30px; font-size: 80%;
text-align: right;">
- Rev. 1512255 by bdelacretaz on Fri, 9 Aug 2013 11:14:51 +0000
+ Rev. 1513470 by bdelacretaz on Tue, 13 Aug 2013 13:11:10 +0000
</div>
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