# Installing ELK (CentOS)

This is a short step-by-step guide on installing ElasticSearch LogStash and Kibana Stack on a CentOS environment to gather and analyze logs.

## I. Install JDK

```
rpm -ivh https://dl.dropboxusercontent.com/u/5756075/jdk-7u45-linux-x64.rpm
```

## II. Install & Configure ElasticSearch

### Add repository

```
rpm --import http://packages.elasticsearch.org/GPG-KEY-elasticsearch
cat > /etc/yum.repos.d/elasticsearch.repo <<EOF
[elasticsearch-1.3]
name=Elasticsearch repository for 1.3.x packages
baseurl=http://packages.elasticsearch.org/elasticsearch/1.3/centos
gpgcheck=1
gpgkey=http://packages.elasticsearch.org/GPG-KEY-elasticsearch
enabled=1
EOF
```

### Install ElasticSearch

```
yum -y install elasticsearch
```

### Configure ElasticSearch

1. Increase the openfile limits to elasticsearch by:

    ```
    echo 'elasticsearch soft nofile 32000' >> /etc/security/limits.conf
    echo 'elasticsearch hard nofile 32000' >> /etc/security/limits.conf
    ```

2. Configure elasticsearch data storage path

    ```
    echo 'path.data: /data/es/logs' >> /etc/elasticsearch/elasticsearch.yml
    mkdir -p /data/es/logs
    chown -R elasticsearch:elasticsearch /data/es/logs
    ```

3. Disallow elasticsearch process from swapping (try to lock the process address space into RAM)

    ```
    sed -i "s|^# bootstrap.mlockall:.*$|bootstrap.mlockall: true|" /etc/elasticsearch/elasticsearch.yml
    ```

4. Change the JVM Size

    ```
    sed -i "s|^#ES_HEAP_SIZE=.*$|ES_HEAP_SIZE=4g|" /etc/sysconfig/elasticsearch
    ```

    > NOTE: Make sure you have enough RAM on the machine before bumping up the value of the ElasticSearch Deamon's JVM Heap Size and make changes accordingly.

5. Start ElasticSearch

    ```
    service elasticsearch start
    ```

## III. Install & Configure Kibana

1. Download Kibana

    ```
    cd /opt
    wget https://download.elasticsearch.org/kibana/kibana/kibana-3.1.0.tar.gz
    tar xzf kibana-3.1.0.tar.gz
    ln -s kibana-3.1.0 kibana
    ```

2. Install Nginx

    ```
    rpm -Uvh http://download.fedoraproject.org/pub/epel/6/i386/epel-release-6-8.noarch.rpm
    yum -y install nginx
    ```

3. Configure Nginx to server kibana

    ```
    mkdir -p /usr/share/nginx/kibana3
    cp -R /opt/kibana/* /usr/share/nginx/kibana3/
    ```

4. Download sample nginx config:

    ```
    cd ~; curl -OL https://raw.githubusercontent.com/elasticsearch/kibana/kibana3/sample/nginx.conf
    sed -i "s|kibana.myhost.org|$(hostname -f)|" nginx.conf
    sed -i "s|root.*/usr/share/kibana3;|root /usr/share/nginx/kibana3;|" nginx.conf
    cp ~/nginx.conf /etc/nginx/conf.d/default.conf
    ```

    > NOTE: If you don't find the sample `nginx.conf` try this: https://github.com/elasticsearch/kibana/blob/kibana3/sample/nginx.conf, it generally should be laying around in some other branch of kibana.

5. Install apache2-utils to generate username and password pair

    ```
    yum -y install httpd-tools-2.2.15
    htpasswd -c /etc/nginx/conf.d/$(hostname -f).htpasswd admin
    ```

6. Start nginx for serving kibana and to make sure that kibana is available after reboot's

    ```
    service nginx start
    chkconfig nginx on
    ```

## IV. Install & Configure LogStash

### Add Repository

```
cat > /etc/yum.repos.d/logstash.repo <<EOF
[logstash-1.4]
name=logstash repository for 1.4.x packages
baseurl=http://packages.elasticsearch.org/logstash/1.4/centos
gpgcheck=1
gpgkey=http://packages.elasticsearch.org/GPG-KEY-elasticsearch
enabled=1
EOF
```

### Install logstash

```
yum -y install logstash logstash-contrib
```

### Generating SSL Certificates
Since we are going to use Logstash Forwarder to ship logs from our Servers to our Logstash Server, we need to create an SSL certificate and key pair. The certificate is used by the Logstash Forwarder to verify the identity of Logstash Server.

Generate the SSL certificate and private key, in the appropriate locations (/etc/pki/tls/...), with the following command:

```
cd /etc/pki/tls; sudo openssl req -x509 -batch -nodes -days 3650 -newkey rsa:2048 -keyout private/logstash-forwarder.key -out certs/logstash-forwarder.crt
```

The `logstash-forwarder.crt` file will be copied to all of the servers that will send logs to Logstash but we will do that a little later. Let's complete our Logstash configuration.

### Configure logstash

```
cat > /etc/logstash/conf.d/01-lumberjack-input.conf <<EOF
input {
  lumberjack {
    port => 5000
    type => "logs"
    ssl_certificate => "/etc/pki/tls/certs/logstash-forwarder.crt"
    ssl_key => "/etc/pki/tls/private/logstash-forwarder.key"
  }
}
EOF
```

This specifies a lumberjack input that will listen on tcp port 5000, and it will use the SSL certificate and private key that we created earlier.

Now lets create another config file, where we will add a filter for syslog messages:

```
cat > /etc/logstash/conf.d/10-syslog.conf <<EOF
filter {
  if [type] == "syslog" {
    grok {
      match => { "message" => "%{SYSLOGTIMESTAMP:syslog_timestamp} %{SYSLOGHOST:syslog_hostname} %{DATA:syslog_program}(?:\[%{POSINT:syslog_pid}\])?: %{GREEDYDATA:syslog_message}" }
      add_field => [ "received_at", "%{@timestamp}" ]
      add_field => [ "received_from", "%{host}" ]
    }
    syslog_pri { }
    date {
      match => [ "syslog_timestamp", "MMM  d HH:mm:ss", "MMM dd HH:mm:ss" ]
    }
  }
}
EOF
```

This filter looks for logs that are labeled as "syslog" type (by a Logstash Forwarder), and it will try to use "grok" to parse incoming syslog logs to make it structured and query-able.

Now lets create another config file to tell logstash to store logs in elasticsearch.

```
cat > /etc/logstash/conf.d/30-lumberjack-output.conf <<EOF
output {
  elasticsearch { host => localhost }
  stdout { codec => rubydebug }
}
EOF
```

### Start logstash

```
service logstash start
```

## V. Setup Logstash Forwarder

Note: Do these steps for each server that you want to send logs to your Logstash Server.

### Copy SSL certificate to logstash forwarder agents from logstash server:

```
scp /etc/pki/tls/certs/logstash-forwarder.crt [user]@[server]:/tmp
```

> NOTE: Replace [user] and [server] with the username you have access to ssh into the logstash agents and the server with hostname/ip-address of logstash agent

### Install logstash forwarder

```
rpm -ivh http://packages.elasticsearch.org/logstashforwarder/centos/logstash-forwarder-0.3.1-1.x86_64.rpm
```

### Install logstash forwarder init script

```
cd /etc/init.d/; sudo curl -o logstash-forwarder http://logstashbook.com/code/4/logstash_forwarder_redhat_init
chmod +x logstash-forwarder
```

```
cat > /etc/sysconfig/logstash-forwarder <<EOF
LOGSTASH_FORWARDER_OPTIONS="-config /etc/logstash-forwarder -spool-size 100"
EOF
```

```
cp /tmp/logstash-forwarder.crt /etc/pki/tls/certs
```

### Configure logstash forwarder

```
LS_SERVER=[LOGSTASH_SERVER_FQDN]
cat > /etc/logstash-forwarder <<EOF
{
  "network": {
    "servers": [ "${LS_SERVER}:5000" ],
    "timeout": 15,
    "ssl ca": "/etc/pki/tls/certs/logstash-forwarder.crt"
  },
  "files": [
    {
      "paths": [
        "/var/log/messages",
        "/var/log/secure"
       ],
      "fields": { "type": "syslog" }
    }
   ]
}
EOF
```

> NOTE: Be sure to replace [LOGSTASH_SERVER_FQDN] with the FQDN of your logstash server