This guide describes the fastest way to install Graylog on RHEL/CentOS 7 and 8. All links and packages are present at the time of writing.

Warning: This guide does not cover security settings! The server administrator must make sure the Graylog server is not publicly exposed and is following security best practices.

Prerequisites

Hint: This guide assumes that any firewall is disabled and traffic can flow across all necessary ports.

Graylog 5.0 requires the following to maintain compatibility with its software dependencies: 

  • OpenJDK 17 (This is embedded in Graylog 5.0 and does not need to be separately installed.)
  • OpenSearch 1.x, 2.x or Elasticsearch 7.10.2
  • MongoDB 5.x or 6.x

MongoDB

Installing MongoDB on Red Hat should follow the tutorial for Red Hat from the MongoDB documentation.

Graylog 5.0 is compatible with MongoDB 5.x-6.x.

First, add the repository file /etc/yum.repos.d/mongodb-org.repo with the following contents:

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[mongodb-org-6.0]
name=MongoDB Repository
baseurl=https://repo.mongodb.org/yum/redhat/$releasever/mongodb-org/6.0/x86_64/
gpgcheck=1
enabled=1
gpgkey=https://www.mongodb.org/static/pgp/server-6.0.asc

After that, install the latest release of MongoDB:

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sudo yum install mongodb-org

Additionally, run these last steps to start MongoDB:

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sudo systemctl --type=service --state=active | grep mongod

Hint: For the following sections on OpenSearch and Elasticsearch, select which data node you will be using for your Graylog instance and complete only the requisite section.

OpenSearch

If you are using OpenSearch as your data node, then follow the steps below to install OpenSearch 2.0.1.

You may prefer to disable transparent hugepages to improve performance before installing.

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sudo echo "Description=Disable Transparent Huge Pages (THP)
DefaultDependencies=no
After=sysinit.target local-fs.target
[Service]
Type=oneshot
ExecStart=/bin/sh -c 'echo never | tee /sys/kernel/mm/transparent_hugepage/enabled > /dev/null'
[Install]
WantedBy=basic.target" | sudo tee /etc/systemd/system/disable-transparent-huge-pages.service

Then:

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sudo systemctl daemon-reload
sudo systemctl enable disable-transparent-huge-pages.service
sudo systemctl start disable-transparent-huge-pages.service

First, install the OpenSearch GPG key:

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sudo rpm --import https://artifacts.opensearch.org/publickeys/opensearch.pgp

Now, install the package:

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sudo rpm -ivh opensearch-2.0.1-linux-x64.rpm

Edit the opensearch.yml file:

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sudo nano /usr/share/opensearch/config/opensearch.yml

At a minimum the following changes are required (for a single instance install):

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cluster.name: 
path.data: /var/lib/opensearch
path.logs: /var/log/opensearch
action.auto_create_index: false
plugins.security.disabled: true
network.host: 0.0.0.0  
discovery.type: single-node

After the installation succeeds, enable the OpenSearch service.

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sudo systemctl enable opensearch

Then, start OpenSearch.

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sudo systemctl start opensearch

Finally, verify that OpenSearch has launched correctly.

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sudo systemctl status opensearch

Elasticsearch

Elasticsearch 7.10.2 is the only version that is compatible with Graylog 5.0; however, we recommend OpenSearch for new Graylog cluster installations.

The following commands will begin the installation of the open-source version of Elasticsearch. See the Elasticsearch install page for more detailed instructions.

First, install the Elasticsearch GPG key:

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rpm --import https://artifacts.elastic.co/GPG-KEY-elasticsearch

Then add the repository file /etc/yum.repos.d/elasticsearch.repo with the following contents:

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sudo rpm --import https://artifacts.elastic.co/GPG-KEY-elasticsearch

echo "[elasticsearch-7.10.2]
name=Elasticsearch repository for 7.10.2 packages
baseurl=https://artifacts.elastic.co/packages/oss-7.x/yum
gpgcheck=1
gpgkey=https://artifacts.elastic.co/GPG-KEY-elasticsearch
enabled=1
autorefresh=1
type=rpm-md" | sudo tee /etc/yum.repos.d/elasticsearch.repo

sudo yum install elasticsearch-oss

Install the 7.10.2 release with:

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sudo yum install elasticsearch-oss

Modify the Elasticsearch configuration file (/etc/elasticsearch/elasticsearch.yml), set the cluster name to graylog, and uncomment action.auto_create_index: false to enable the action:

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echo "cluster.name: graylog
action.auto_create_index: false" | sudo tee /etc/elasticsearch/elasticsearch.yml

After you have modified the configuration, you can start Elasticsearch:

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sudo systemctl daemon-reload
sudo systemctl enable elasticsearch.service
sudo systemctl restart elasticsearch.service
sudo systemctl --type=service --state=active | grep elasticsearch

Graylog

Now install the Graylog repository configuration and Graylog itself with the following commands:

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sudo rpm -Uvh https://packages.graylog2.org/repo/packages/graylog-5.0-repository_latest.rpm
sudo yum install graylog-server

If you are installing Graylog Operations, then you will use the following commands:

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sudo rpm -Uvh https://packages.graylog2.org/repo/packages/graylog-5.0-repository_latest.rpm
sudo yum install graylog-enterprise

Edit the Configuration File

Read the instructions within the configurations file and edit as needed, located at /etc/graylog/server/server.conf. Additionally add password_secret and root_password_sha2 as these are mandatory and Graylog will not start without them.

To create your root_password_sha2, run the following command:

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echo -n "Enter Password: " && head -1 </dev/stdin | tr -d '\n' | sha256sum | cut -d" " -f1

To generate a password_secret:

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pwgen -N 1 -s 96

To be able to connect to Graylog, set http_bind_address to the public host name or a public IP address of the machine with which you can connect. More information about these settings can be found in Configuring the Web Interface.

Hint: If you’re operating a single-node setup and would like to use HTTPS for the Graylog web interface and the Graylog REST API, it’s possible to use NGINX or Apache as a reverse proxy.

The last step is to enable Graylog during the operating system’s start up:

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sudo systemctl daemon-reload
sudo systemctl enable graylog-server.service
sudo systemctl start graylog-server.service
sudo systemctl --type=service --state=active | grep graylog

The next step is to ingest messages into your Graylog and extract the messages with extractors or use the Pipelines to work with the messages.

SELinux Information

Hint: We assume that you have policycoreutils-python installed to manage SELinux.

If you’re using SELinux on your system, you need to take care of the following settings:

  • Allow the web server to access the network:sudo setsebool -P httpd_can_network_connect 1
  • If the policy above does not comply with your security policy, you can also allow access to each port individually:
    • Graylog REST API and web interface:sudo semanage port -a -t http_port_t -p tcp 9000
    • Elasticsearch (only if the HTTP API is being used):sudo semanage port -a -t http_port_t -p tcp 9200
  • Allow using MongoDB’s default port (27017/tcp):sudo semanage port -a -t mongod_port_t -p tcp 27017

If you run a single server environment with NGINX or Apache proxy, enabling the Graylog REST API is enough. All other rules are only required in a multi-node setup. Having SELinux disabled during installation and enabling it later requires you to manually check the policies for MongoDB, OpenSearch, Elasticsearch, and Graylog.

Hint: Depending on your actual setup and configuration, you might need to add more SELinux rules to get to a running setup.

Further Reading

Multiple Server Setup

If you plan to have multiple server taking care of different roles in your cluster like we have in this big production setup you need to modify only a few settings. This is covered in our Multi-Node Setup guide. The Default File Location guide will give you the file you need to modify in your setup.