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Subject svn commit: r1513470 - in /sling/site/trunk/content/documentation/bundles: jconsole-hc.jpg sling-hc-plugin.jpg sling-health-check-tool.mdtext
Date Tue, 13 Aug 2013 13:11:10 GMT
Author: bdelacretaz
Date: Tue Aug 13 13:11:10 2013
New Revision: 1513470

SLING-2987 - rewrite according to redesign


Modified: sling/site/trunk/content/documentation/bundles/jconsole-hc.jpg
Binary files - no diff available.

Modified: sling/site/trunk/content/documentation/bundles/sling-hc-plugin.jpg
Binary files - no diff available.

Modified: sling/site/trunk/content/documentation/bundles/sling-health-check-tool.mdtext
--- sling/site/trunk/content/documentation/bundles/sling-health-check-tool.mdtext (original)
+++ sling/site/trunk/content/documentation/bundles/sling-health-check-tool.mdtext Tue Aug
13 13:11:10 2013
@@ -1,91 +1,77 @@
 Title: Sling Health Check Tool
-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 _system attributes_ that the rules
+Based on simple _HealthCheck_ 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.
-<div class="warning">
-This module is being extensively redesigned as part of SLING-2987 - the code that is described
-is available at
and for now
-this page is out of sync with the current trunk code.
-The rules evaluation results are available in JSON format via HTTP requests, as a Webconsole
-and via JMX.
+Health checks are easily extensible either by configuring the supplied default _HealthCheck_
services, or
+by implementing your own services.  
 Default rules are provided to check JMX MBeans, OSGi bundle states, disabling of default
 accounts, JUnit tests results and the output of scripts written in any language supported
by Sling.
-Custom rules can be created by supplying _RuleBuilder_ OSGi services, see the _hc-sling_
and _sling-demo_ modules for examples.
 The source code of the hc modules is at [](
-## Example rules
-A set of example rules is provided as [initial content in the sling-demo module][1].
-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.
-1. Start a standalone Sling instance from _launchpad/builder_
-1. Optionally install the bundle, version 1.0.8 or later, if
you want to enable JUnit-based rules.
-1. Build the _contrib/extensions/healthcheck_ modules.
-1. From that module, install the ,
, and bundles.
-1. Open the health check webconsole at _/system/console/healthcheck_ and follow the instructions.
The bundle provides a set of example rules under _/apps/hc_
, you can use that for testing.
+## What's a HealthCheck ?
-You can also see the raw output of the rules execution servlet (as admin) at _/apps/hc/demo.healthcheck.json_

-and the example rules content at _/apps/hc/demo.tidy.infinity.json_ .
+A _HealthCheck_ is just an OSGi service that returns a _Result_.
-Rules can have a multi-value _tags_ property that allows them to be executed in groups. Entering
_sling,bundles_ as tags in the webconsole 
-plugin form, or using them as selectors ( _/apps/hc/
) demonstrates this feature.
+The Result provides a _Status_ (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 `` class in the for more details. 
+HealthCheck services can be selected for execution based on their _tags_. The _HealthCheckFilter_
+accepts positive and negative tag parameters, so that `-security,sling` for example selects
all HealthCheck
+having the _sling_ tag but not the _security_ tag. 
+## Executing health checks
+Besides executing them programatically, Health checks can be executed via a webconsole plugin
or via JMX, 
+see below for more details.
+## Default HealthCheck services and samples
+As of mid-August 2013, the `` bundle provides OSGi configurations
that demonstrate the following HealthCheck services:
+ * `JmxAttributeHealthCheck` checks the value of a single JMX attribute and supports ranges
like _between 12 and 42_.  
+ * `SlingRequestStatusHealthCheck` checks the HTTP status of Sling requests.  
+ * `ScriptableHealthCheck` evaluates an expression written in any scripting language that
Sling supports, and provides bindings to access JMX attributes and OSGi bundles states. 
+ * `DefaultLoginsHealthCheck` can be used to verify that the default Sling logins fail. 

+ * `CompositeHealthCheck` executes a set of HealthCheck selected by tags, useful to get higher-level
management views.
+## Configuring health checks
+Health check services are created via OSGi configurations.
+Here's a `ScriptableHealthCheck` example configuration provided by the ``
+  PID =
+  Factory PID =
+ = InactiveBundlesCheck
+ = No inactive bundles
+  hc.tags = [bundles, script]
+  expression = osgi.inactiveBundlesCount() == 0 
+  language.extension = ecma
+Properties starting with the `hc.` prefix should be provided by all HealthCheck services.
 ## Webconsole plugin
-As mentioned above, a webconsole plugin at _/system/console/healthcheck_ 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").
+A webconsole plugin at `/system/console/healthcheck` allows for executing health checks,
optionally selected
+based on their tags.
-The screenshot below shows an example, as of svn revision 1490286.
+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.
+The screenshot below shows an example, as of svn revision 1513462.
-## JMX interfaces
+## JMX access to health checks
+A JMX MBean is created for each HealthCheck, which gives access to the `Result` and the log,
as shown
+on the screenshot below.   
+The MBean name defaults to the `` service property of the _HealthCheck_, but if an
+`` property is provided it is used instead. That property can include a a slash

+(as in `composite/security`) to define the MBean service name, which by default is _HealthCheck_.
-### Accessing and combining JMX attributes in scripted rules
-Although the basic _jmxbeans_ 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.
-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.

-    {
-        "sling:resourceType" : "sling/healthcheck/rules",
-        "namespace": "script",
-        "ruleName": "Example javascript expression that combines two JMX attributes",
-        "qualifier": "ecma",
-        "expression": 
-            'jmx.attribute("java.lang:type=ClassLoading", "LoadedClassCount") > 100 
-            && jmx.attribute("osgi.core:type=framework,version=1.5","FrameworkStartLevel")
> 1',
-        "tags" : ["script","javascript", "jmx" ],
-        "jcr:primaryType": "nt:unstructured"
-    } 
-### JMX access to Health Check Rules results
-Creating OSGi configurations causes the results
of health 
-check rules to be made available via JMX MBeans in the JMX
-The slingdemo module provides an [example configuration][2], which is used in the screenshot
-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 JMX tree root,  and an optional set of rules tags to select
which rules 
-to include.
-Multiple _RulesMBeans_ 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.
+The example configurations of the `` bundle demonstrate the various
-## Known issues
-See [SLING-2822]( for details.
-  [1]:
-  [2]:

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