The graylog-ctl script

Some packages of Graylog (for example the virtual machine appliances) ship with a pre-installed graylog-ctl script to allow you easy configuration of certain settings.


graylog-ctl is only available in the virtual machine appliances, but not in the tar-ball (for manual setup), operating system packages, or configuration management scripts (Puppet, Chef, Ansible).

Configuration commands

The following commands are changing the configuration of Graylog:

Command Description
sudo graylog-ctl set-admin-password <password>
Set a new admin password
sudo graylog-ctl set-admin-username <username>
Set a different username for the admin user
sudo graylog-ctl set-email-config
<smtp server> [--port=<smtp port>
--web-url=<graylog web-interface url>
--no-tls --no-ssl]
Configure SMTP settings to send alert mails
sudo graylog-ctl set-timezone <zone acronym>

Set Graylog’s time zone from a list of valid time zones. Make sure system time is also set correctly with sudo dpkg-reconfigure tzdata.
sudo graylog-ctl enforce-ssl
Enforce HTTPS for the web interface
sudo graylog-ctl set-node-id <id>
Override random server node id
sudo graylog-ctl set-server-secret <secret>
Override server secret used for encryption
sudo graylog-ctl disable-internal-logging
Disable sending internal logs (e. g. nginx) from the VM to Graylog. Reboot is needed for activation!
sudo graylog-ctl set-external-ip
http[s]://<public IP>:port/
Configure an external IP in the Nginx proxy. This is needed to connect the web interface to the REST API e.g. in NAT’d networks or on AWS.
sudo graylog-ctl set-listen-address
--service <web|rest|transport|endpoint>
--address http://<host>:port
Set the listen address for the web interface, REST API, and the transport URI. As well as the endpoint uri that is used by the web browser to connect to the API. Can be used to deal with additional network interfaces.
sudo graylog-ctl local-connect
Bind all services but the web interface to
sudo graylog-ctl set-mongodb-password [-a|-g]
-u <username> -p <password>
Activate MongoDB authentication and set a password for an admin or unprivileged service user
sudo graylog-ctl backup-etcd
Backup the cluster configuration stored in etcd. See also the restore notes.

Commands for multi node setups:

Command Description
sudo graylog-ctl set-cluster-master <IP of master node>
Set IP address of node where others can fetch cluster configuration from
sudo graylog-ctl reconfigure-as-backend
Run Graylog server and Elasticsearch on this node
sudo graylog-ctl reconfigure-as-datanode
Run Elasticsearch on this node only
sudo graylog-ctl reconfigure-as-server
Run Graylog server on this node only

General commands:

Command Description
sudo graylog-ctl cleanse
Delete all graylog data, and start from scratch
sudo graylog-ctl graceful-kill
Attempt a graceful stop, then SIGKILL the entire process group
sudo graylog-ctl hup
Send the services a HUP signal
sudo graylog-ctl int
Send the services an INT signal
sudo graylog-ctl term
Send the services a TERM signal
sudo graylog-ctl kill
Send the services a KILL signal
sudo graylog-ctl list-servers
List all Graylog servers in your cluster
sudo graylog-ctl status
Show the status of all the services
sudo graylog-ctl start
Start services if they are down, and restart them if they stop
sudo graylog-ctl stop
Stop the services, and do not restart them
sudo graylog-ctl restart
Stop the services if they are running, then start them again
sudo graylog-ctl once
Start the services if they are down. Do not restart them if they stop
sudo graylog-ctl uninstall
Kill all processes and uninstall the process supervisor (data will be preserved)
sudo graylog-ctl tail
Watch the service logs of all enabled services
sudo graylog-ctl tail <service name>
Watch the logs of just one service, name can be ‘server’, ‘elasticsearch’, ‘mongodb’, ‘nginx’, ‘etcd’
sudo graylog-ctl show-config
Show the service configuration
sudo graylog-ctl reconfigure
Reconfigure the application


After using a command that changes the application configuration re-run sudo graylog-ctl reconfigure to actually enable the changes.

Multi VM setup

At some point it make sense to not run all services on a single VM anymore. For performance reasons you might want to add more Elasticsearch nodes to the cluster or even add a second Graylog server. This can be achieved by changing IP addresses in the Graylog configuration files by hand or use our canned configurations which come with the graylog-ctl command.

The idea is to have one VM which is a central point for other VMs to fetch all needed configuration settings to join the cluster. Typically the first VM you spin up is used for this task. Automatically an instance of etcd is started and filled with the necessary settings for other hosts.

For example, to create a small cluster with a dedicated Graylog server node and another for Elasticsearch, spin up two VMs from the same Graylog image. On the first one start only Graylog and MongoDB:

vm1> sudo graylog-ctl set-admin-password sEcReT
vm1> sudo graylog-ctl reconfigure-as-server

On the second VM start only Elasticsearch. Before doing so set the IP of the first VM to fetch the configuration data from there:

vm2> sudo graylog-ctl set-cluster-master <ip-of-vm1>
vm2> sudo graylog-ctl reconfigure-as-datanode

vm1> sudo graylog-ctl reconfigure-as-server

This results in a perfectly fine dual VM setup. However if you want to scale this setup out by adding an additional Elasticsearch node, you can proceed in the same way:

vm3> sudo graylog-ctl set-cluster-master <ip-of-vm1>
vm3> sudo graylog-ctl reconfigure-as-datanode

vm1> sudo graylog-ctl reconfigure-as-server
vm2> sudo graylog-ctl reconfigure-as-datanode

Verify that all nodes are working as a cluster by going to the Kopf plugin on one of the Elasticsearch nodes open http://vm2:9200/_plugin/kopf/#!/nodes.

Important: In case you want to add a second Graylog server you have to set the same server secret on all machines. The secret is stored in the file /etc/graylog/graylog-secrets and can be applied to other hosts with the set-server-secret sub-command.

The following configuration modes do exist:

Command Services
sudo graylog-ctl reconfigure Regenerate configuration files based on /etc/graylog/graylog-services.json
sudo graylog-ctl reconfigure-as-server Run Graylog, web and MongoDB (no Elasticsearch)
sudo graylog-ctl reconfigure-as-backend Run Graylog, Elasticsearch and MongoDB (no nginx for web interface access)
sudo graylog-ctl reconfigure-as-datanode Run only Elasticsearch
sudo graylog-ctl enable-all-services Run all services on this box

A server with only the web interface running is not supported as of Graylog 2.0. The web interface is now included in the server process. But you can create your own service combinations by editing the file /etc/graylog/graylog-services.json by hand and enable or disable single services. Just run graylog-ctl reconfigure afterwards.

Extend disk space

All data of the appliance setup is stored in /var/opt/graylog/data. In order to extend the disk space mount a second (virtual) hard drive into this directory.


Make sure to move old data to the new drive before and give the graylog user permissions to read and write here.

Example procedure for the Graylog virtual appliance


These steps require basic knowledge in using Linux and the common shell programs.

  • Shutdown the virtual machine as preparation for creating a consistent snapshot.

  • Take a snapshot of the virtual machine in case something goes wrong.

  • Attach an additional hard drive to the virtual machine.

  • Start the virtual machine again.

  • Stop all services to prevent disk access:

    $ sudo graylog-ctl stop
  • Check for the logical name of the new hard drive. Usually this is /dev/sdb:

    $ sudo lshw -class disk
  • Partition and format new disk:

    $ sudo parted -a optimal /dev/sdb mklabel gpt
    # A reboot may be necessary at this point so that the updated GPT is being recognized by the operating system
    $ sudo parted -a optimal -- /dev/sdb unit compact mkpart primary ext3 "1" "-1"
    $ sudo mkfs.ext4 /dev/sdb1
  • Mount disk into temporary directory /mnt/tmp:

    $ sudo mkdir /mnt/tmp
    $ sudo mount /dev/sdb1 /mnt/tmp
  • Copy current data to new disk:

    $ sudo cp -ax /var/opt/graylog/data/* /mnt/tmp/
  • Compare both folders:

    # Output should be: Only in /mnt/tmp: lost+found
    $ sudo diff -qr --suppress-common-lines /var/opt/graylog/data /mnt/tmp
  • Delete old data:

    $ sudo rm -rf /var/opt/graylog/data/*
  • Mount new disk into /var/opt/graylog/data directory:

    $ sudo umount /mnt/tmp
    $ sudo mount /dev/sdb1 /var/opt/graylog/data
  • Make change permanent by adding an entry to /etc/fstab:

    $ echo '/dev/sdb1 /var/opt/graylog/data ext4 defaults 0 0' | sudo tee -a /etc/fstab
  • Reboot virtual machine:

    $ sudo shutdown -r now

Install Graylog plugins

The Graylog plugin directory is located in /opt/graylog/plugin/. Just drop a JAR file there and restart the server with sudo graylog-ctl restart graylog-server to load the plugin.

Install Elasticsearch plugins

Elasticsearch comes with a helper program to install additional plugins you can call it like this sudo JAVA_HOME=/opt/graylog/embedded/jre /opt/graylog/elasticsearch/bin/plugin

Install custom SSL certificates

During the first reconfigure run self signed SSL certificates are generated. You can replace this certificate with your own to prevent security warnings in your browser. Just drop the key and combined certificate file here: /opt/graylog/conf/nginx/ca/graylog.crt respectively /opt/graylog/conf/nginx/ca/graylog.key. Afterwards restart nginx with sudo graylog-ctl restart nginx.

Assign a static IP

Per default the appliance make use of DHCP to setup the network. If you want to access Graylog under a static IP please follow these instructions:

$ sudo ifdown eth0

Edit the file /etc/network/interfaces like this (just the important lines):

auto eth0
  iface eth0 inet static
  address <static IP address>
  netmask <netmask>
  gateway <default gateway>
  pre-up sleep 2

Activate the new IP and reconfigure Graylog to make use of it:

$ sudo ifup eth0
$ sudo graylog-ctl reconfigure

Wait some time until all services are restarted and running again. Afterwards you should be able to access Graylog with the new IP.

Upgrade Graylog


The Graylog omnibus package does not support unattended upgrading from Graylog 1.x to Graylog 2.x!


The Graylog omnibus package 2.3.0 and later, which contains Elasticsearch 5.5.0, can not be used in environments which have been running the Graylog omnibus package 1.x before and which still have indices created by Elasticsearch before version 2.0.0!

Always perform a full backup or snapshot of the appliance before proceeding. Only upgrade if the release notes say the next version is a drop-in replacement. Choose the Graylog version you want to install from the list of Omnibus packages . graylog_latest.deb always links to the newest version:

$ wget
$ sudo graylog-ctl stop
$ sudo dpkg -G -i graylog_latest.deb
$ sudo graylog-ctl backup-etcd
$ sudo graylog-ctl reconfigure
$ sudo reboot


In case the etcd service won’t start after the upgrade, an error is shown like:

Connection refused - connect(2) for "" port 4001``

Please flush and restore the etcd database like it’s shown in the restore notes.

Migrate manually from 1.x to 2.x

To update a 1.x appliance to 2.x the administrator has to purge the Graylog installation, migrate the stored log data and install the new version as Omnibus package. Before upgrading read the upgrade notes. This procedure can potentially delete log data or configuration settings. So it’s absolutely necessary to perform a backup or a snapshot before!

Stop all services but Elasticsearch:

$ sudo -s
$ graylog-ctl stop graylog-web
$ graylog-ctl stop graylog-server
$ graylog-ctl stop mongodb
$ graylog-ctl stop nginx
$ graylog-ctl stop etcd

Check for index range types. The output of this command should be {}, if not read these notes for how to fix this:

$ curl -XGET <appliance_IP>:9200/_all/_mapping/index_range; echo

Delete the Graylog index template:

$ curl -X DELETE <appliance_IP>:9200/_template/graylog-internal

Migrate appliance configuration:

$ cd /etc
$ mv graylog graylog2.2
$ vi graylog2.2/graylog-secrets.json

# Remove the graylog_web section
},  << don't forget the comma!
"graylog_web": {
  "secret_token": "3552c87f3e3..."

$ vi graylog2.2/graylog-services.json

# Remove the graylog_web section
}, << don't forget the comma!
"graylog_web": {
  "enabled": true

$ vi graylog2.2/graylog-settings.json

# Remove "rotation_size", "rotation_time", "indices"
"enforce_ssl": false,
"rotation_size": 1073741824,
"rotation_time": 0,
"indices": 10,
"journal_size": 1,

Migrate appliance data:

$ cd /var/opt
$ mv graylog graylog2.2
$ mv graylog2.2/data/elasticsearch/graylog2 graylog2.2/data/elasticsearch/graylog

Delete old Graylog version and install new Omnibus package:

$ wget
$ apt-get purge graylog
$ dpkg -i graylog_2.2.1-1_amd64.deb

Move directories back:

$ cd /etc
$ mv graylog2.2 graylog
$ cd /var/opt/
$ mv graylog2.2 graylog

Reconfigure and Reboot:

$ graylog-ctl reconfigure
$ reboot

Graylog should now be updated and old data still available.


The index retention configuration moved from the Graylog configuration file to the web interface. After the first start go to ‘System -> Indices -> Update configuration’ to re-enable your settings.

Advanced Settings

To change certain parameters used by graylog-ctl during a reconfigure run you can override all default parameters found in the attributes file.

If you want to change the username used by Graylog for example, edit the file /etc/graylog/graylog-settings.json like this:

"custom_attributes": {
  "user": {
    "username": "log-user"

Afterwards run sudo graylog-ctl reconfigure and sudo graylog-ctl restart. The first command renders all changed configuration files and the later makes sure that all services restart to activate the change.

There are a couple of other use cases of this, e.g. change the default data directories used by Graylog to /data (make sure this is writeable by the graylog user):

"custom_attributes": {
    "elasticsearch": {
      "data_directory": "/data/elasticsearch"
    "mongodb": {
      "data_directory": "/data/mongodb"
    "etcd": {
      "data_directory": "/data/etcd"
    "graylog-server": {
      "journal_directory": "/data/journal"

Or change the default memory settings used by Graylog or Elasticsearch:

"custom_attributes": {
     "graylog-server": {
       "memory": "1700m"
     "elasticsearch": {
       "memory": "2200m"

Again, run reconfigure and restart afterwards to activate the changes.

Securing an appliance

Even though the Graylog appliances are not meant for production use there are still two commands you can use to increase the security of an installation. With graylog-ctl local-connect only the web interface is reachable from the outside. All other services are listening on the local loopback device. This is only useful when you run the appliance as a single node. Clustered setups are not possible anymore. But data stored in MongoDB or Elastcsearch are protected from direct external access.

The other one is graylog-ctl set-mongodb-password. This command enables authentication for MongoDB and creates or updates a database user. First an admin user should be created. This user is needed for database maintenance and future password changes. Afterwards an unprivileged service user can be created for Graylog. The procedure works like this:

$ graylog-ctl set-mongodb-password -a -u admin -p someAdminPassword123
$ graylog-ctl set-mongodb-password -g -u graylog -p someGraylogServicePassword
$ graylog-ctl reconfigure

MongoDB and the Graylog server will be restarted with activated authentication. The username and password needs to be set on every Graylog node to make a cluster work. Login to another Graylog server and only set the service user:

$ graylog-ctl set-cluster-master
$ graylog-ctl set-mongodb-password -g -u graylog -p someGraylogServicePassword
$ graylog-ctl reconfigure-as-server

Since the pre-build appliances are based on standard Ubuntu-Linux, tools like iptables/SELinux/AppArmor can be used additionally. But to explain all available countermeasurements would go beyond this documentation.

Restore cluster configuration

With graylog-ctl backup-etcd a backup of the cluster configuration of a multi node setup can be created. In order to restore this backup copy the wal-file back to the data directory:

$ graylog-ctl stop etcd
$ rm -r /var/opt/graylog/data/etcd/member/*
$ cp /var/opt/graylog/backup/etcd/<timestamp>/member/wal /var/opt/graylog/data/etcd/member/
$ chown -R graylog.graylog /var/opt/graylog/data/etcd/member/wal
$ su -c '/opt/graylog/embedded/sbin/etcd -data-dir=/var/opt/graylog/data/etcd -force-new-cluster' graylog
$ graylog-ctl start etcd