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In this post, we will provide step-by-step set-up instructions for the collection and visualization of system logs in a DevOps cloud-native app architecture with the use of the Elastic Stack – Logstash, Elasticsearch and Kibana.
Sometimes we need to look through the logs, searching for the required lines on several servers; to do this, we log in and look for the logs repeating the same commands on the servers.
Suppose we have 3 MX servers, and some customer files a complaint on a missing message; which he sent abroad to his wife at a particular time.
Using the ELK stack, or Elastic Stack as it is also referred to (E-elasticsearch L-logstash K-kibana), we can find that message in the logs in a couple of clicks.
The part you have to replace is marked in italic.
What we use for building the centralized logging system
– Centos 7: The most recent version of the operation system
– Logstash: Server-based part for processing incoming logs
– Elasticsearch: For storing logs
– Kibana: Web interface for searching through and visualizing the logs
– Logstash Forwarder: It is installed on the servers as an agent for sending logs to a logstash server.
We will install the first three components on our collection server, and Logstash Forwarder on the servers we want to collect logs from.
Install Java 8
Java is needed for Logstash and Elasticsearch. We are going to install OpenJDK 8.
cd /opt sudo wget --no-cookies --no-check-certificate --header "Cookie: gpw_e24=http%3A%2F%2Fwww.oracle.com%2F; oraclelicense=accept-securebackup-cookie" "https://download.oracle.com/otn-pub/java/jdk/8u40-b25/jre-8u40-linux-x64.tar.gz"
Unpack
sudo tar xvf jre-8*.tar.gz
Grant the necessary rights:
sudo chown -R root: jre1.8*
Create simlinks with the use of alternatives:
sudo alternatives --install /usr/bin/java java /opt/jre1.8*/bin/java 1
Delete the downloaded archive
sudo rm /opt/jre-8*.tar.gz
Install Elasticsearch
Import Elasticsearch public GPG key:
sudo rpm --import http://packages.elasticsearch.org/GPG-KEY-elasticsearch
Create and edit the repository file for Elasticsearch:
sudo vi /etc/yum.repos.d/elasticsearch.repo
[elasticsearch-1.4] name=Elasticsearch repository for 1.4.x packages baseurl=http://packages.elasticsearch.org/elasticsearch/1.4/centos gpgcheck=1 gpgkey=http://packages.elasticsearch.org/GPG-KEY-elasticsearch enabled=1
Install Elasticsearch
sudo yum -y install elasticsearch-1.4.4
Modify the configuration file:
sudo vi /etc/elasticsearch/elasticsearch.yml
Close access to elascticsearch from the outside:
network.host: localhost
Run Elasticsearch:
sudo systemctl start elasticsearch.service
And add it to the autorun:
sudo systemctl enable elasticsearch.service
Install Kibana:
Download and unpack Kibana 4:
cd ~; wget https://download.elasticsearch.org/kibana/kibana/kibana-4.0.1-linux-x64.tar.gz; tar xvf kibana-*.tar.gz
Edit the configuration file:
vi ~/kibana-4*/config/kibana.yml
In the Kibana configuration file, find the line that determines the host and replace the IP (0.0.0.0 by default) with the IP from the localhost:
host: "localhost"
This parameter indicates that Kibana will be accessible only locally. This is good, as we will use the reverse proxy server Nginx to grant access from the outside.
sudo mkdir -p /opt/kibana
And relocate the unpacked files there:
sudo cp -R ~/kibana-4*/* /opt/kibana/
Kibana is run as /opt/kibana/bin/kibana, but we will run it as a service. Create Kibana Systemd:
sudo vi /etc/systemd/system/kibana4.service
[Service] ExecStart=/opt/kibana/bin/kibana Restart=always StandardOutput=syslog StandardError=syslog SyslogIdentifier=kibana4 User=root Group=root Environment=NODE_ENV=production [Install] WantedBy=multi-user.target
Now, run it and add it to the autorun
sudo systemctl start kibana4
sudo systemctl enable kibana4Set epel repository
sudo yum -y install epel-release
Install Nginx
sudo yum -y install nginx httpd-tools
Using htpasswd, create a user and a password
sudo htpasswd -c /etc/nginx/htpasswd.users kibanaadmin
Now, edit the main configuration nginx.com:
sudo vi /etc/nginx/nginx.conf
Find and delete the whole section server{}. Two lines should remain at the end
include /etc/nginx/conf.d/*.conf; }
Now, create the configuration file nginx for kibana4
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; } }
Run Nginx:
sudo systemctl start nginx
sudo systemctl enable nginxNow, Kibana is accessible at https://FQDN/
Install Logstash:
Create the repository file for Logstash:
sudo vi /etc/yum.repos.d/logstash.repo [logstash-1.5] name=logstash repository for 1.5.x packages baseurl=http://packages.elasticsearch.org/logstash/1.5/centos gpgcheck=1 gpgkey=http://packages.elasticsearch.org/GPG-KEY-elasticsearch enabled=1
Save and exit
Install Logstash:
sudo yum -y install logstash
Generate SSL certificates
Generate certificates for checking server authenticity
cd /etc/pki/tls sudo openssl req -subj '/CN=logstash_server_fqdn/' -x509 -days 3650 -batch -nodes -newkey rsa:2048 -keyout private/logstash-forwarder.key -out certs/logstash-forwarder.crt
The file logstash-forwarder.crt should be copied to all servers, which will send logs to the Logstash server
Configure Logstash:
The configuration files for Logstash are written in json format and are located at /etc/logstash/conf.d. Configuration includes 3 sections: inputs, filters, and outputs.
Create file 01-lumberjack-input.conf and set up “lumberjack” input (the protocol used by Logstash and Logstash Forwarder to communicate)
sudo vi /etc/logstash/conf.d/01-lumberjack-input.conf input { lumberjack { port => 5000 type => "logs" ssl_certificate => "/etc/pki/tls/certs/logstash-forwarder.crt" ssl_key => "/etc/pki/tls/private/logstash-forwarder.key" } }
Save and exit. It was noted here that lumberjack will listen to TCP port 5000 and will use the certificates we had generated before.
Now, create a file named 10-syslog.conf, and add it to the settings of syslog messages filtration:
sudo vi /etc/logstash/conf.d/10-syslog.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 exit
Create the last file 30-lumberjack-output.conf:
sudo vi /etc/logstash/conf.d/30-lumberjack-output.conf output { elasticsearch { host => localhost } stdout { codec => rubydebug } }
Restart Logstash:
sudo service logstash restartNow that Logstash is set up, we go to Logstash Forwarder
Set up Logstash Forwarder
Copy the SSL certificate to the server where Logstash Forwarder will work
scp /etc/pki/tls/certs/logstash-forwarder.crt [email protected]_private_IP:/tmp
Download the key:
sudo rpm --import http://packages.elasticsearch.org/GPG-KEY-elasticsearch
Create the repository configuration file:
sudo vi /etc/yum.repos.d/logstash-forwarder.repo
Creating repo for Logstash Forwarder
[logstash-forwarder] name=logstash-forwarder repository baseurl=http://packages.elasticsearch.org/logstashforwarder/centos gpgcheck=1 gpgkey=http://packages.elasticsearch.org/GPG-KEY-elasticsearch enabled=1
Install Logstash Forwarder
sudo yum -y install logstash-forwarder
Copy the certificates to the required location:
sudo cp /tmp/logstash-forwarder.crt /etc/pki/tls/certs/
Let’s get to setting it up:
sudo vi /etc/logstash-forwarder.conf
"servers": [ "logstash_server_private_IP:5000" ], "timeout": 15, "ssl ca": "/etc/pki/tls/certs/logstash-forwarder.crt" Между квадратнымы скобками вставляем { "paths": [ "/var/log/messages", "/var/log/secure" ], "fields": { "type": "syslog" } }
Add Logstash Forwarder to the autorun and run it:
sudo service logstash-forwarder restart
Now, Logstash Forwarder will send logs to your Logstash server.
Enter kibana, open Dashboard, and enjoy the view.
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