How To Install ElasticSearch,Logstash and Kibana(ELK Stack)on CentOS 7

墨蓝 2022-05-31 01:59 238阅读 0赞

## Prerequisites ##

To complete this tutorial, you will require root access to an CentOS 7 VPS. Instructions to set that up can be found here (steps 3 and 4): [Initial Server Setup with CentOS 7][].

If you would prefer to use Ubuntu instead, check out this tutorial: [How To Install ELK on Ubuntu 14.04][].

The amount of CPU, RAM, and storage that your ELK Server will require depends on the volume of logs that you intend to gather. For this tutorial, we will be using a VPS with the following specs for our ELK Server:

*  OS: CentOS 7
 *  RAM: 4GB
 *  CPU: 2

In addition to your ELK Server, you will want to have a few other servers that you will gather logs from.

Let's get started on setting up our ELK Server!

## Install Java 8 ##

Elasticsearch and Logstash require Java, so we will install that now. We will install a recent version of Oracle Java 8 because that is what Elasticsearch recommends. It should, however, work fine with OpenJDK, if you decide to go that route. Following the steps in this section means that you accept the Oracle Binary License Agreement for Java SE.

Change to your home directory and download the Oracle Java 8 (Update 73, the latest at the time of this writing) JDK RPM with these commands:

cd ~ 
       wget --no-cookies --no-check-certificate --header "Cookie: gpw_e24=http%3A%2F%2Fwww.oracle.com%2F; oraclelicense=accept-securebackup-cookie" "http://download.oracle.com/otn-pub/java/jdk/8u73-b02/jdk-8u73-linux-x64.rpm"

Then install the RPM with this yum command (if you downloaded a different release, substitute the filename here):

sudo yum -y localinstall jdk-8u73-linux-x64.rpm

Now Java should be installed at `/usr/java/jdk1.8.0_73/jre/bin/java`, and linked from `/usr/bin/java`.

You may delete the archive file that you downloaded earlier:

rm ~/jdk-8u*-linux-x64.rpm

Now that Java 8 is installed, let's install ElasticSearch.

## Install Elasticsearch ##

Elasticsearch can be installed with a package manager by adding Elastic's package repository.

Run the following command to import the Elasticsearch public GPG key into rpm:

sudo rpm --import http://packages.elastic.co/GPG-KEY-elasticsearch

Create a new yum repository file for Elasticsearch. Note that this is a single command:

echo '[elasticsearch-2.x] 
       name=Elasticsearch repository for 2.x packages 
       baseurl=http://packages.elastic.co/elasticsearch/2.x/centos 
       gpgcheck=1 
       gpgkey=http://packages.elastic.co/GPG-KEY-elasticsearch 
       enabled=1 
       ' | sudo tee /etc/yum.repos.d/elasticsearch.repo

Install Elasticsearch with this command:

sudo yum -y install elasticsearch

Elasticsearch is now installed. Let's edit the configuration:

sudo vi /etc/elasticsearch/elasticsearch.yml

You will want to restrict outside access to your Elasticsearch instance (port 9200), so outsiders can't read your data or shutdown your Elasticsearch cluster through the HTTP API. Find the line that specifies`network.host`, uncomment it, and replace its value with "localhost" so it looks like this:

elasticsearch.yml excerpt (updated)

network.host: localhost

Save and exit `elasticsearch.yml`.

Now start Elasticsearch:

sudo systemctl start elasticsearch

Then run the following command to start Elasticsearch automatically on boot up:

sudo systemctl enable elasticsearch

Now that Elasticsearch is up and running, let's install Kibana.

## Install Kibana ##

The Kibana package shares the same GPG Key as Elasticsearch, and we already installed that public key.

Create and edit a new yum repository file for Kibana:

sudo vi /etc/yum.repos.d/kibana.repo

Add the following repository configuration:

/etc/yum.repos.d/kibana.repo

[kibana-4.4] 
       name=Kibana repository for 4.4.x packages 
       baseurl=http://packages.elastic.co/kibana/4.4/centos 
       gpgcheck=1 
       gpgkey=http://packages.elastic.co/GPG-KEY-elasticsearch 
       enabled=1

Save and exit.

Install Kibana with this command:

sudo yum -y install kibana

Open the Kibana configuration file for editing:

sudo vi /opt/kibana/config/kibana.yml

In the Kibana configuration file, find the line that specifies `server.host`, and replace the IP address ("0.0.0.0" by default) with "localhost":

kibana.yml excerpt (updated)

server.host: "localhost"

Save and exit. This setting makes it so Kibana will only be accessible to the localhost. This is fine because we will install an Nginx reverse proxy, on the same server, to allow external access.

Now start the Kibana service, and enable it:

sudo systemctl start kibana 
       sudo chkconfig kibana on

Before we can use the Kibana web interface, we have to set up a reverse proxy. Let's do that now, with Nginx.

## Install Nginx ##

Because we configured Kibana to listen on `localhost`, we must set up a reverse proxy to allow external access to it. We will use Nginx for this purpose.

Note: If you already have an Nginx instance that you want to use, feel free to use that instead. Just make sure to configure Kibana so it is reachable by your Nginx server (you probably want to change the `host`value, in `/opt/kibana/config/kibana.yml`, to your Kibana server's private IP address). Also, it is recommended that you enable SSL/TLS.

Add the EPEL repository to yum:

sudo yum -y install epel-release

Now use yum to install Nginx and httpd-tools:

sudo yum -y install nginx httpd-tools

Use htpasswd to create an admin user, called "kibanaadmin" (you should use another name), that can access the Kibana web interface:

sudo htpasswd -c /etc/nginx/htpasswd.users kibanaadmin

Enter a password at the prompt. Remember this login, as you will need it to access the Kibana web interface.

Now open the Nginx configuration file in your favorite editor. We will use vi:

sudo vi /etc/nginx/nginx.conf

Find the default server block (starts with `server {`), the last configuration block in the file, and delete it. When you are done, the last two lines in the file should look like this:

nginx.conf excerpt

include /etc/nginx/conf.d/*.conf;
    }

Save and exit.

Now we will create an Nginx server block in a new file:

sudo vi /etc/nginx/conf.d/kibana.conf

Paste the following code block into the file. Be sure to update the `server_name` to match your server's name:

/etc/nginx/conf.d/kibana.conf

server { 
       listen 80; 
       
       server_name example.com; 
       
       auth_basic "Restricted Access"; 
       auth_basic_user_file /etc/nginx/htpasswd.users; 
       
       location / { 
       proxy_pass http://localhost:5601; 
       proxy_http_version 1.1; 
       proxy_set_header Upgrade $http_upgrade; 
       proxy_set_header Connection 'upgrade'; 
       proxy_set_header Host $host; 
       proxy_cache_bypass $http_upgrade; 
       } 
       }

Save and exit. This configures Nginx to direct your server's HTTP traffic to the Kibana application, which is listening on `localhost:5601`. Also, Nginx will use the `htpasswd.users` file, that we created earlier, and require basic authentication.

Now start and enable Nginx to put our changes into effect:

sudo systemctl start nginx 
       sudo systemctl enable nginx

Note: This tutorial assumes that SELinux is disabled. If this is not the case, you may need to run the following command for Kibana to work properly: `sudo setsebool -P httpd_can_network_connect 1`

Kibana is now accessible via your FQDN or the public IP address of your ELK Server i.e.[http://elk\\\_server\\\_public\\\_ip/][http_elk_server_public_ip]. If you go there in a web browser, after entering the "kibanaadmin" credentials, you should see a Kibana welcome page which will ask you to configure an index pattern. Let's get back to that later, after we install all of the other components.

## Install Logstash ##

The Logstash package shares the same GPG Key as Elasticsearch, and we already installed that public key, so let's create and edit a new Yum repository file for Logstash:

sudo vi /etc/yum.repos.d/logstash.repo

Add the following repository configuration:

/etc/yum.repos.d/logstash.repo

[logstash-2.2] 
       name=logstash repository for 2.2 packages 
       baseurl=http://packages.elasticsearch.org/logstash/2.2/centos 
       gpgcheck=1 
       gpgkey=http://packages.elasticsearch.org/GPG-KEY-elasticsearch 
       enabled=1

Save and exit.

Install Logstash with this command:

sudo yum -y install logstash

Logstash is installed but it is not configured yet.

## Generate SSL Certificates ##

Since we are going to use Filebeat to ship logs from our Client Servers to our ELK Server, we need to create an SSL certificate and key pair. The certificate is used by Filebeat to verify the identity of ELK Server. Create the directories that will store the certificate and private key with the following commands:

Now you have two options for generating your SSL certificates. If you have a DNS setup that will allow your client servers to resolve the IP address of the ELK Server, use Option 2. Otherwise, Option 1 will allow you to use IP addresses.

### Option 1: IP Address ###

If you don't have a DNS setup—that would allow your servers, that you will gather logs from, to resolve the IP address of your ELK Server—you will have to add your ELK Server's private IP address to the`subjectAltName` (SAN) field of the SSL certificate that we are about to generate. To do so, open the OpenSSL configuration file:

sudo vi /etc/pki/tls/openssl.cnf

Find the `[ v3_ca ]` section in the file, and add this line under it (substituting in the ELK Server's private IP address):

openssl.cnf excerpt

subjectAltName = IP: ELK_server_private_ip

Save and exit.

Now generate the SSL certificate and private key in the appropriate locations (/etc/pki/tls/), with the following commands:

cd /etc/pki/tls 
       sudo openssl req -config /etc/pki/tls/openssl.cnf -x509 -days 3650 -batch -nodes -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. If you went with this option, skip option 2 and move on to Configure Logstash.

### Option 2: FQDN (DNS) ###

If you have a DNS setup with your private networking, you should create an A record that contains the ELK Server's private IP address—this domain name will be used in the next command, to generate the SSL certificate. Alternatively, you can use a record that points to the server's public IP address. Just be sure that your servers (the ones that you will be gathering logs from) will be able to resolve the domain name to your ELK Server.

Now generate the SSL certificate and private key, in the appropriate locations (/etc/pki/tls/...), with the following command (substitute in the FQDN of the ELK Server):

cd /etc/pki/tls 
       sudo openssl req -subj '/CN=ELK_server_fqdn/' -x509 -days 3650 -batch -nodes -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 ##

Logstash configuration files are in the JSON-format, and reside in /etc/logstash/conf.d. The configuration consists of three sections: inputs, filters, and outputs.

Let's create a configuration file called `02-beats-input.conf` and set up our "filebeat" input:

sudo vi /etc/logstash/conf.d/02-beats-input.conf

Insert the following input configuration:

02-beats-input.conf

input { 
       beats { 
       port => 5044 
       ssl => true 
       ssl_certificate => "/etc/pki/tls/certs/logstash-forwarder.crt" 
       ssl_key => "/etc/pki/tls/private/logstash-forwarder.key" 
       } 
       }

Save and quit. This specifies a `beats` input that will listen on tcp port `5044`, and it will use the SSL certificate and private key that we created earlier.

Now let's create a configuration file called `10-syslog-filter.conf`, where we will add a filter for syslog messages:

sudo vi /etc/logstash/conf.d/10-syslog-filter.conf

Insert the following syslog filter configuration:

10-syslog-filter.conf

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" ] 
       } 
       } 
       }

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

Lastly, we will create a configuration file called `30-elasticsearch-output.conf`:

sudo vi /etc/logstash/conf.d/30-elasticsearch-output.conf

Insert the following output configuration:

/etc/logstash/conf.d/30-elasticsearch-output.conf

output { 
       elasticsearch { 
       hosts => ["localhost:9200"] 
       sniffing => true 
       manage_template => false 
       index => "%{[@metadata][beat]}-%{+YYYY.MM.dd}" 
       document_type => "%{[@metadata][type]}" 
       } 
       }

Save and exit. This output basically configures Logstash to store the beats data in Elasticsearch which is running at `localhost:9200`, in an index named after the beat used (filebeat, in our case).

If you want to add filters for other applications that use the Filebeat input, be sure to name the files so they sort between the input and the output configuration (i.e. between 02- and 30-).

Test your Logstash configuration with this command:

sudo service logstash configtest

It should display `Configuration OK` if there are no syntax errors. Otherwise, try and read the error output to see what's wrong with your Logstash configuration.

Restart and enable Logstash to put our configuration changes into effect:

sudo systemctl restart logstash 
       sudo chkconfig logstash on

Next, we'll load the sample Kibana dashboards.

## Load Kibana Dashboards ##

Elastic provides several sample Kibana dashboards and Beats index patterns that can help you get started with Kibana. Although we won't use the dashboards in this tutorial, we'll load them anyway so we can use the Filebeat index pattern that it includes.

First, download the sample dashboards archive to your home directory:

cd ~ 
       curl -L -O https://download.elastic.co/beats/dashboards/beats-dashboards-1.1.0.zip

Install the `unzip` package with this command:

sudo yum -y install unzip

Next, extract the contents of the archive:

unzip beats-dashboards-*.zip

And load the sample dashboards, visualizations and Beats index patterns into Elasticsearch with these commands:

cd beats-dashboards-* 
       ./load.sh

These are the index patterns that we just loaded:

*  \[packetbeat-\]YYYY.MM.DD
 *  \[topbeat-\]YYYY.MM.DD
 *  \[filebeat-\]YYYY.MM.DD
 *  \[winlogbeat-\]YYYY.MM.DD

When we start using Kibana, we will select the Filebeat index pattern as our default.

## Load Filebeat Index Template in Elasticsearch ##

Because we are planning on using Filebeat to ship logs to Elasticsearch, we should load a Filebeat index template. The index template will configure Elasticsearch to analyze incoming Filebeat fields in an intelligent way.

First, download the Filebeat index template to your home directory:

cd ~ 
       curl -O https://gist.githubusercontent.com/thisismitch/3429023e8438cc25b86c/raw/d8c479e2a1adcea8b1fe86570e42abab0f10f364/filebeat-index-template.json

Then load the template with this command:

curl -XPUT 'http://localhost:9200/_template/filebeat?pretty' -d@filebeat-index-template.json

If the template loaded properly, you should see a message like this:

Output:
     
      {
      "acknowledged" : true
    }

Now that our ELK Server is ready to receive Filebeat data, let's move onto setting up Filebeat on each client server.

## Set Up Filebeat (Add Client Servers) ##

Do these steps for each CentOS or RHEL 7 server that you want to send logs to your ELK Server. For instructions on installing Filebeat on Debian-based Linux distributions (e.g. Ubuntu, Debian, etc.), refer to the [Set Up Filebeat (Add Client Servers) section][Set Up Filebeat _Add Client Servers_ section] of the Ubuntu variation of this tutorial.

### Copy SSL Certificate ###

On your ELK Server, copy the SSL certificate—created in the prerequisite tutorial—to your Client Server(substitute the client server's address, and your own login):

scp /etc/pki/tls/certs/logstash-forwarder.crt user@client_server_private_address:/tmp

After providing your login's credentials, ensure that the certificate copy was successful. It is required for communication between the client servers and the ELK Server.

Now, on your Client Server, copy the ELK Server's SSL certificate into the appropriate location (/etc/pki/tls/certs):

sudo mkdir -p /etc/pki/tls/certs 
       sudo cp /tmp/logstash-forwarder.crt /etc/pki/tls/certs/

Now we will install the Topbeat package.

### Install Filebeat Package ###

On Client Server, create run the following command to import the Elasticsearch public GPG key into rpm:

sudo rpm --import http://packages.elastic.co/GPG-KEY-elasticsearch

Create and edit a new yum repository file for Filebeat:

sudo vi /etc/yum.repos.d/elastic-beats.repo

Add the following repository configuration:

/etc/yum.repos.d/elastic-beats.repo

[beats] 
       name=Elastic Beats Repository 
       baseurl=https://packages.elastic.co/beats/yum/el/$basearch 
       enabled=1 
       gpgkey=https://packages.elastic.co/GPG-KEY-elasticsearch 
       gpgcheck=1

Save and exit.

Install Filebeat with this command:

sudo yum -y install filebeat

Filebeat is installed but it is not configured yet.

### Configure Filebeat ###

Now we will configure Filebeat to connect to Logstash on our ELK Server. This section will step you through modifying the example configuration file that comes with Filebeat. When you complete the steps, you should have a file that looks something like [this][].

On Client Server, create and edit Filebeat configuration file:

sudo vi /etc/filebeat/filebeat.yml

Note: Filebeat's configuration file is in YAML format, which means that indentation is very important! Be sure to use the same number of spaces that are indicated in these instructions.

Near the top of the file, you will see the `prospectors` section, which is where you can define prospectorsthat specify which log files should be shipped and how they should be handled. Each prospector is indicated by the `-` character.

We'll modify the existing prospector to send `secure` and `messages` logs to Logstash. Under `paths`, comment out the `- /var/log/*.log` file. This will prevent Filebeat from sending every `.log` in that directory to Logstash. Then add new entries for `syslog` and `auth.log`. It should look something like this when you're done:

filebeat.yml excerpt 1 of 5

...
          paths:
     - /var/log/secure
     - /var/log/messages
    #        - /var/log/*.log
    ...

Then find the line that specifies `document_type:`, uncomment it and change its value to "syslog". It should look like this after the modification:

filebeat.yml excerpt 2 of 5

...
          document_type: syslog
    ...

This specifies that the logs in this prospector are of type syslog (which is the type that our Logstash filter is looking for).

If you want to send other files to your ELK server, or make any changes to how Filebeat handles your logs, feel free to modify or add prospector entries.

Next, under the `output` section, find the line that says `elasticsearch:`, which indicates the Elasticsearch output section (which we are not going to use). Delete or comment out the entire Elasticsearch output section (up to the line that says `logstash:`).

Find the commented out Logstash output section, indicated by the line that says `#logstash:`, and uncomment it by deleting the preceding `#`. In this section, uncomment the `hosts: ["localhost:5044"]`line. Change `localhost` to the private IP address (or hostname, if you went with that option) of your ELK server:

filebeat.yml excerpt 3 of 5

### Logstash as output
      logstash:
        # The Logstash hosts
        hosts: ["ELK_server_private_IP:5044"]

This configures Filebeat to connect to Logstash on your ELK Server at port 5044 (the port that we specified an input for earlier).

Directly under the `hosts` entry, and with the same indentation, add this line:

filebeat.yml excerpt 4 of 5

bulk_max_size: 1024

Next, find the `tls` section, and uncomment it. Then uncomment the line that specifies`certificate_authorities`, and change its value to `["/etc/pki/tls/certs/logstash-forwarder.crt"]`. It should look something like this:

filebeat.yml excerpt 5 of 5

...
     tls:
          # List of root certificates for HTTPS server verifications
          certificate_authorities: ["/etc/pki/tls/certs/logstash-forwarder.crt"]

This configures Filebeat to use the SSL certificate that we created on the ELK Server.

Save and quit.

Now start and enable Filebeat to put our changes into place:

sudo systemctl start filebeat 
       sudo systemctl enable filebeat

Again, if you're not sure if your Filebeat configuration is correct, compare it against this [example Filebeat configuration][this].

Now Filebeat is sending your syslog `messages` and `secure` files to your ELK Server! Repeat this section for all of the other servers that you wish to gather logs for.

## Test Filebeat Installation ##

If your ELK stack is setup properly, Filebeat (on your client server) should be shipping your logs to Logstash on your ELK server. Logstash should be loading the Filebeat data into Elasticsearch in an date-stamped index, `filebeat-YYYY.MM.DD`.

On your ELK Server, verify that Elasticsearch is indeed receiving the data by querying for the Filebeat index with this command:

curl -XGET 'http://localhost:9200/filebeat-*/_search?pretty'

You should see a bunch of output that looks like this:

Sample Output:
     
      ...
    {
          "_index" : "filebeat-2016.01.29",
          "_type" : "log",
          "_id" : "AVKO98yuaHvsHQLa53HE",
          "_score" : 1.0,
          "_source":{"message":"Feb  3 14:34:00 rails sshd[963]: Server listening on :: port 22.","@version":"1","@timestamp":"2016-01-29T19:59:09.145Z","beat":{"hostname":"topbeat-u-03","name":"topbeat-u-03"},"count":1,"fields":null,"input_type":"log","offset":70,"source":"/var/log/auth.log","type":"log","host":"topbeat-u-03"}
        }
    ...

If your output shows 0 total hits, Elasticsearch is not loading any logs under the index you searched for, and you should review your setup for errors. If you received the expected output, continue to the next step.

## Connect to Kibana ##

When you are finished setting up Filebeat on all of the servers that you want to gather logs for, let's look at Kibana, the web interface that we installed earlier.

In a web browser, go to the FQDN or public IP address of your ELK Server. After entering the "kibanaadmin" credentials, you should see a page prompting you to configure a default index pattern:

![Create index][]

Go ahead and select \[filebeat\]-YYY.MM.DD from the Index Patterns menu (left side), then click the Star (Set as default index) button to set the Filebeat index as the default.

Now click the Discover link in the top navigation bar. By default, this will show you all of the log data over the last 15 minutes. You should see a histogram with log events, with log messages below:

![Discover page][]

Right now, there won't be much in there because you are only gathering syslogs from your client servers. Here, you can search and browse through your logs. You can also customize your dashboard.

Try the following things:

*  Search for "root" to see if anyone is trying to log into your servers as root
 *  Search for a particular hostname (search for `host: "hostname"`)
 *  Change the time frame by selecting an area on the histogram or from the menu above
 *  Click on messages below the histogram to see how the data is being filtered

Kibana has many other features, such as graphing and filtering, so feel free to poke around!

## Conclusion ##

Now that your syslogs are centralized via Elasticsearch and Logstash, and you are able to visualize them with Kibana, you should be off to a good start with centralizing all of your important logs. Remember that you can send pretty much any type of log or indexed data to Logstash, but the data becomes even more useful if it is parsed and structured with grok.

To improve your new ELK stack, you should look into gathering and filtering your other logs with Logstash, and [creating Kibana dashboards][]. You may also want to [gather system metrics by using Topbeat][] with your ELK stack. All of these topics are covered in the other tutorials in this series.

[Initial Server Setup with CentOS 7]: https://www.digitalocean.com/community/tutorials/initial-server-setup-with-centos-7
[How To Install ELK on Ubuntu 14.04]: https://www.digitalocean.com/community/tutorials/how-to-install-elasticsearch-logstash-and-kibana-elk-stack-on-ubuntu-14-04
[http_elk_server_public_ip]: http://elk%5C_server%5C_public%5C_ip/
[Set Up Filebeat _Add Client Servers_ section]: https://www.digitalocean.com/community/tutorials/how-to-install-elasticsearch-logstash-and-kibana-elk-stack-on-ubuntu-14-04#set-up-filebeat%28add-client-servers%29
[this]: https://gist.githubusercontent.com/thisismitch/3429023e8438cc25b86c/raw/de660ffdd3decacdcaf88109e5683e1eef75c01f/filebeat.yml-centos
[Create index]: https://assets.digitalocean.com/articles/elk/1-filebeat-index.gif
[Discover page]: https://assets.digitalocean.com/articles/elk/2-filebeat-discover.png
[creating Kibana dashboards]: https://www.digitalocean.com/community/tutorials/how-to-use-kibana-dashboards-and-visualizations
[gather system metrics by using Topbeat]: https://www.digitalocean.com/community/tutorials/how-to-gather-infrastructure-metrics-with-topbeat-and-elk-on-centos-7