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https://issues.apache.org/jira/browse/CLOUDSTACK-3471

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Introduction

As of cloudstack 4.3 there is no api that can aggregate log messages by the job id. Since logging is a typically a service that can be and is usually available outside the IaaS core, it was felt that instead of integrating this as an api within cloudstack, it would be better to provide a generic logsearch service that could be invoked by cloudstack to retrieve log messages. We describe the mechanism on how to achieve this in what follows.

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In this configuration any linux user template can be used to spawn elasticsearch nodes. The number of such nodes should be configurable via a global parameter. One of the node will be designated as the master node, which will also run the redis instance.

Logstash Configuration on the log shipping layer.

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input {
  redis {
    host => "<host>"
    # these settings should match the output of the agent
    data_type => "list"
    key => "logstash"
    # We use the 'json' codec here because we expect to read
    # json events from redis.
    codec => json
  }
}
filter
{
        grok
        {
                match => [ "message","%{YEAR:year}-%{MONTHNUM:month}-%{MONTHDAY}[T ]%{HOUR}:?%{MINUTE}:?%{SECOND}[T ]INFO%{GREEDYDATA}job[\-]+%{INT:jobid}\s*=\s*\[\s*%{UUID:uuid}\s*\]%{GREEDYDATA}"]
                named_captures_only => true
        }
}
output
{
  stdout { debug => true debug_format => "json"}
  elasticsearch {
        host => "<host>"
  }
}

Steps in setting up the service:

1. Deploy a vm intance from any existing linux based user template
2. setup logstash on this guest instance
   1. There is a an apt repository and a yum repository from which logstash can be deployed.
3. setup elasticsearch on this guest instance
   1. There is a an apt repository and a yum repository from which logstash can be deployed.
4. Setup redis on this guest instance
   1. For yum : This is available from the REMI repository
   2. For apt : This is available from thethe  ppa:rwky/redis
5. Create a template from this virtual machine
6. Subsequently this template can be used to spawn elasticsearch master and slave nodes.

Config for example elasticsearch cluster:

This will help configuring unicast discovery of master nodes. Multicast discovery can also be used but is not described here. By default all nodes are enabled to function as master. The actual master is elected through a elasticsearch master election process.

On each elasticsearch node:

• Edit the file /etc/elasticsearch/elasticsearch.yml, replace host1, host2 and so on with the actual ip address of the nodes.

discovery.zen.ping.unicast.hosts: ["host1", "host2"]

• Edit the file /etc/elasticsearch/elasticsearch.yml, replace host1 with the nodes ip address

network.publish_host: host1

Automation:

The following two scripts can automate steps 1 to 5 for the above process.

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This script takes all the paramters in a setup config file. The only line param this requires is the config file. Default setup.conf is adequately commented
to describe the required params.

 ~# ./setup_es_template.sh --config setup.conf

Default setup.conf:

#########################################################################################################
#This is the base template which will be used to provision a guest with logstash,elasticsearch and redis
templateid=

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#The yum repo url for elasticsearch
elasticsearch_baseurl="http://packages.elasticsearch.org/elasticsearch/10.090/centos"

#Description for elasticsearch software
elasticsearch_desc="Elasticsearch repository for 1 0.090.x packages"

#The gpg key for repo
elasticsearch_gpgkey="http://packages.elasticsearch.org/GPG-KEY-elasticsearch"
#The elasticsearch reponame
elasticsearch_reponame="\[elasticsearch-10.090\]"

#The epel repo rpm
epelrpm=http://dl.fedoraproject.org/pub/epel/6/x86_64/epel-release-6-8.noarch.rpm
#The remi repo rpm
remirpm=http://rpms.famillecollet.com/enterprise/remi-release-6.rpm

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import org.apache.commons.httpclient.HttpStatus;
import org.apache.http.entity.StringEntity;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.HttpResponse;
import org.apache.http.impl.client.DefaultHttpClient;
import java.io.*;
class SampleSearch
{
        public static void main(String []args)
        {
                try{
                DefaultHttpClient httpClient = new DefaultHttpClient();
                String url  = "http://192.168.56.100:9200/_search" ;
                StringEntity data = new StringEntity("{ \"query\": { \"query_string\": { \"query\": \"2005\", \"fields\" : [\"jobid\"] } } }");
                HttpPost request  = new HttpPost(url);
                request.addHeader("content-type", "application/x-www-form-urlencoded");
                request.setEntity(data);
                HttpResponse response = httpClient.execute(request);
                         if(response.toString().contains("200 OK"))
                        {
                                InputStream is = response.getEntity().getContent();
                                BufferedReader in = new BufferedReader(new InputStreamReader(is));
                                String line = null;
                                StringBuilder responseData = new StringBuilder();
                                while((line = in.readLine()) != null)
                                {
                                        responseData.append(line);
                                }
                                System.out.println("RESPONSE : " + responseData.toString());
                        }
                }
                catch(Exception exp)
                {
                        System.out.println("Error ocurred:" + exp.toString());
                }
        }
}

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