/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The SF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing,
* software distributed under the License is distributed on an
* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
* KIND, either express or implied. See the License for the
* specific language governing permissions and limitations under the License.
*/
package org.apache.sling.hc.core.impl;
import java.util.HashSet;
import java.util.Set;
import javax.script.Bindings;
import javax.script.ScriptEngine;
import javax.script.ScriptEngineManager;
import org.apache.felix.scr.annotations.Activate;
import org.apache.felix.scr.annotations.Component;
import org.apache.felix.scr.annotations.ConfigurationPolicy;
import org.apache.felix.scr.annotations.Properties;
import org.apache.felix.scr.annotations.Property;
import org.apache.felix.scr.annotations.PropertyUnbounded;
import org.apache.felix.scr.annotations.Reference;
import org.apache.felix.scr.annotations.ReferenceCardinality;
import org.apache.felix.scr.annotations.ReferencePolicy;
import org.apache.felix.scr.annotations.Service;
import org.apache.sling.commons.osgi.PropertiesUtil;
import org.apache.sling.hc.api.HealthCheck;
import org.apache.sling.hc.api.Result;
import org.apache.sling.hc.util.FormattingResultLog;
import org.apache.sling.scripting.api.BindingsValuesProvider;
import org.osgi.service.component.ComponentContext;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/** {@link HealthCheck} that checks a scriptable expression */
@Component(
configurationFactory=true,
policy=ConfigurationPolicy.REQUIRE,
metatype=true,
label="Apache Sling Scriptable Health Check",
description="Uses scripted expressions to verify multiple JMX attributes or other values.")
@Properties({
@Property(name=HealthCheck.NAME,
label="Name",
description="Name of this health check."),
@Property(name=HealthCheck.TAGS, unbounded=PropertyUnbounded.ARRAY,
label="Tags",
description="List of tags for this health check, used to select " +
"subsets of health checks for execution e.g. by a composite health check."),
@Property(name=HealthCheck.MBEAN_NAME,
label="MBean Name",
description="Name of the MBean to create for this health check. If empty, no MBean is registered.")
})
@Service(value=HealthCheck.class)
public class ScriptableHealthCheck implements HealthCheck {
private final Logger log = LoggerFactory.getLogger(getClass());
private String expression;
private String languageExtension;
private static final String DEFAULT_LANGUAGE_EXTENSION = "ecma";
@Property(label="Expression",
description="The value of this expression must be \"true\" for this check to be successful.")
public static final String PROP_EXPRESSION = "expression";
@Property(value=DEFAULT_LANGUAGE_EXTENSION,
label="Language Extension",
description="File extension of the language to use to evaluate the " +
"expression, for example \"ecma\" or \"groovy\", asssuming the corresponding script engine " +
"is available. By default \"ecma\" is used.")
public static final String PROP_LANGUAGE_EXTENSION = "language.extension";
@Reference
private ScriptEngineManager scriptEngineManager;
@Reference(
cardinality=ReferenceCardinality.OPTIONAL_MULTIPLE,
policy=ReferencePolicy.DYNAMIC,
referenceInterface=BindingsValuesProvider.class,
target="(context=healthcheck)")
private final Set<BindingsValuesProvider> bindingsValuesProviders = new HashSet<BindingsValuesProvider>();
@Activate
protected void activate(ComponentContext ctx) {
expression = PropertiesUtil.toString(ctx.getProperties().get(PROP_EXPRESSION), "");
languageExtension = PropertiesUtil.toString(ctx.getProperties().get(PROP_LANGUAGE_EXTENSION), DEFAULT_LANGUAGE_EXTENSION);
log.debug("Activated scriptable health check name={}, languageExtension={}, expression={}",
new Object[] {ctx.getProperties().get(HealthCheck.NAME),
languageExtension, expression});
}
@Override
public Result execute() {
final FormattingResultLog resultLog = new FormattingResultLog();
resultLog.debug("Checking expression [{}], language extension=[{}]", expression, languageExtension);
try {
final ScriptEngine engine = scriptEngineManager.getEngineByExtension(languageExtension);
if (engine == null) {
resultLog.healthCheckError("No ScriptEngine available for extension {}", languageExtension);
} else {
// Set Bindings, with our ResultLog as a binding first, so that other bindings can use it
final Bindings b = engine.createBindings();
b.put(FormattingResultLog.class.getName(), resultLog);
synchronized (bindingsValuesProviders) {
for(BindingsValuesProvider bvp : bindingsValuesProviders) {
log.debug("Adding Bindings provided by {}", bvp);
bvp.addBindings(b);
}
}
log.debug("All Bindings added: {}", b.keySet());
final Object value = engine.eval(expression, b);
if(value!=null && "true".equals(value.toString().toLowerCase())) {
resultLog.debug("Expression [{}] evaluates to true as expected", expression);
} else {
resultLog.warn("Expression [{}] does not evaluate to true as expected, value=[{}]", expression, value);
}
}
} catch (final Exception e) {
resultLog.healthCheckError(
"Exception while evaluating expression [{}] with language extension [{}]: {}",
expression, languageExtension, e);
}
return new Result(resultLog);
}
public void bindBindingsValuesProvider(BindingsValuesProvider bvp) {
synchronized (bindingsValuesProviders) {
bindingsValuesProviders.add(bvp);
}
log.debug("{} registered: {}", bvp, bindingsValuesProviders);
}
public void unbindBindingsValuesProvider(BindingsValuesProvider bvp) {
synchronized (bindingsValuesProviders) {
bindingsValuesProviders.remove(bvp);
}
log.debug("{} unregistered: {}", bvp, bindingsValuesProviders);
}
}