Mattermost is an open source, self-hosted Slack-alternative. As an alternative to proprietary SaaS messaging, Mattermost brings all your team communication into one place, making it searchable and accessible anywhere.

Mattermost is included as a template on OrionVM for quick and easy deployment. This section will guide you through the process of provisioning a Mattermost instance as well as basic configuration so you can get started using it immediately!

Creating Your Mattermost Instance

You create a Mattermost instance from a template, much like an Ubuntu or CentOS instance. From the Dashboard screen, click the Launch Instance button, which will redirect you to the Instances screen.

On the Instances screen the New Instance panel will display. Under the second column labeled Disks, under New Instance Boot Disk select Mattermost from the dropdown list. Feel free to rename the instance by clicking the pencil icon next to the name at the top.

The suggested minimum specs for a Mattermost instance for 250-500 users are as follows:

  • 2 vCPU
  • 4GB RAM
  • 100 GB Boot Disk
  • 1 Public IP Address

To allocate 2 vCPU's and 4GB of RAM at the same time the Performance Tier must be set to High CPU. Please also ensure that you have at least one Public IP address allocated under Networking.

Once you have defined your requirements, click Create and Start to create and start the instance.

On the Instances screen, for the Mattermost instance you just created, copy the Public IP and paste it into the URL bar of a new tab in your browser, followed by ":8065". For example, if your IP address is you would type "" into the URL bar and press enter.

You will now be redirected to the signup page for the first user. Fill in the email, username and password fields as instructed and click Create Account.

As no teams currently exist, you will be prompted to create one. Click Create a new team then specify the Team Name and Team URL when prompted.

You will then be redirected to the Town Square text channel logged in as the user just created.

Inviting Users

In the Town Square text channel, click the Invite others to this team link to bring up the Team Invite Link window. Send this link to the people you would like to invite to your Mattermost team.

When the recipient inputs the address into their browser they will be prompted to create an account in a similar way to when you created the first user.

Once both users are created and connected you should now be able to chat!

Sending Files Through Mattermost

To attach a file to a message in Mattermost click the Paperclip to the right of the message input box. A file browser window will then display through which you can select your file.

If the file attached is an image, a preview of the image will display next to your message text, which can be sent together by pressing enter.