SampleMonitorEntity

SampleMonitorEntity.java

package io.cloudsoft.ibm.mms.amp.util;

import brooklyn.config.ConfigKey;
import brooklyn.enricher.Enrichers;
import brooklyn.entity.basic.AbstractEntity;
import brooklyn.entity.basic.Attributes;
import brooklyn.entity.basic.ConfigKeys;
import brooklyn.event.AttributeSensor;
import brooklyn.event.basic.Sensors;
import brooklyn.event.feed.http.HttpFeed;
import brooklyn.event.feed.http.HttpPollConfig;
import brooklyn.event.feed.http.HttpValueFunctions;
import brooklyn.util.flags.SetFromFlag;
import brooklyn.util.guava.Functionals;
import brooklyn.util.guava.IfFunctions;
import brooklyn.util.math.MathPredicates;
import brooklyn.util.time.Duration;

import com.google.api.client.repackaged.com.google.common.base.Preconditions;
import com.google.common.base.Functions;

/**
 * Sample entity which represents an external resource, in this case a Github repository
 * specified by its URL, reporting the number of repositories
 * <p>
 * Can deploy to Brooklyn with a JAR containing this placed in the lib/dropins/ directory.
 * (Alternatively you can use the brooklyn maven archetype to create your own distributable,
 * or build as an OSGi bundle and add to the Brooklyn catalog pointing to the OSGi bundle with a URL.
 * <p>
 * The following YAML will then deploy it:
<code>

services:
- type: io.cloudsoft.ibm.mms.amp.util.SampleMonitorEntity
  name: Cloudsoft Repo
  brooklyn.config:
    sample.targetUrl: https://api.github.com/orgs/cloudsoft
    sample.minReposRequired: 500

# but note, the github rate limit is very low, 60 reqs / hour
</code>   
 */
public class SampleMonitorEntity extends AbstractEntity {

    @SetFromFlag("target_url")
    ConfigKey<String> TARGET_URL = ConfigKeys.newStringConfigKey("sample.targetUrl", "The target URL"
        // optional default value
        , "https://api.github.com/orgs/apache"
        );
    
    @SetFromFlag("min_repos_required")
    ConfigKey<Integer> MIN_REPOS_REQUIRED = ConfigKeys.newIntegerConfigKey("sample.minReposRequired", "Number of repositories required for service to be happy",
        2);
    
    AttributeSensor<String> REPO_NAME = Sensors.newStringSensor("sample.repoName");
    AttributeSensor<Integer> REPO_COUNT = Sensors.newIntegerSensor("sample.repoCount");
    AttributeSensor<Boolean> SERVICE_IS_HAPPY = Sensors.newBooleanSensor("sample.happy");
    
    @Override
    public void init() {
        super.init();
        connectSensors();
    }

    private void connectSensors() {
        String url = getConfig(TARGET_URL);
        Preconditions.checkNotNull(url, "Must supply: "+TARGET_URL);
        
        HttpFeed.builder().baseUri(url)
            .entity(this)
            .period(Duration.FIVE_MINUTES)
            
            .poll(HttpPollConfig.forSensor(REPO_NAME)
                .onSuccess(HttpValueFunctions.<String>jsonContentsFromPath("name"))
                )
            .poll(HttpPollConfig.forSensor(REPO_COUNT)
                .onSuccess(HttpValueFunctions.<Integer>jsonContentsFromPath("public_repos"))
                .onFailureOrException(Functions.<Integer>constant(null))
                )
                
            .poll(HttpPollConfig.forSensor(SERVICE_IS_HAPPY)
                .onSuccess(Functionals.chain(HttpValueFunctions.<Integer>jsonContentsFromPath("public_repos"),
                    Functions.forPredicate(MathPredicates.greaterThan(6))))
                .onFailureOrException(Functions.constant(false))
                )
                
            .build();
        
        // update the "service_up" status, using the build in "not-up-indicators", based on service_is_happy
        addEnricher(
            Enrichers.builder().updatingMap(Attributes.SERVICE_NOT_UP_INDICATORS).from(SERVICE_IS_HAPPY)
                .computing(IfFunctions.ifNotEquals(true).value("Not enough repos here!").defaultValue(null))
                .build());
    }
    
}

SampleMonitorEntity.yaml

# simply drop this into the "add application" -> "yaml" tab of a running brooklyn instance
# (no setup needed - but use a recent snapshot version, >= Sept 2014)

services:
- type: brooklyn.entity.basic.BasicEntity
  name: Sample REST Monitor
  entity.initializers:
  - type: brooklyn.entity.software.http.HttpRequestSensor
    brooklyn.config:
      name: sample.repoCount
      period: 5m
      uri: https://api.github.com/orgs/apache
      jsonPath: public_repos