Running Flatcar Container Linux on a Vultr VPS

    These instructions will walk you through running a single Flatcar Container Linux node. This guide assumes:

    • You have an account at Vultr.com .
    • You have a public + private key combination generated. Here’s a helpful guide if you need to generate these keys: How to set up SSH keys .

    The simplest option to boot up Flatcar Container Linux is to select the “Flatcar Container Linux Stable” operating system from Vultr’s default offerings. However, most deployments require a custom cloud-config, which can only be achieved in Vultr with an iPXE script. The remainder of this article describes this process.

    Cloud-config

    First, you’ll need to make a shell script containing your cloud-config available at a public URL:

    cloud-config-bootstrap.sh:

    #!/bin/bash
    
    cat > "cloud-config.yaml" <<EOF
    #cloud-config
    
    ssh_authorized_keys:
      - ssh-rsa ...
    EOF
    
    sudo flatcar-install -d /dev/vda -c cloud-config.yaml
    sudo reboot
    

    Please be sure to check out Using Cloud-Config .

    You must add to your ssh public key to your cloud-config’s ssh authorized keys so you’ll be able to log in.

    Choosing a channel

    Flatcar Container Linux is designed to be updated automatically with different schedules per channel. You can disable this feature , although we don’t recommend it. Read the release notes for specific features and bug fixes.

    The Alpha channel closely tracks master and is released frequently. The newest versions of system libraries and utilities will be available for testing. The current version is Flatcar Container Linux 3874.0.0.

    A sample script will look like this:

    #!ipxe
    
    # Location of your shell script.
    set cloud-config-url http://example.com/cloud-config-bootstrap.sh
    
    set base-url https://alpha.release.flatcar-linux.net/amd64-usr/current
    kernel ${base-url}/flatcar_production_pxe.vmlinuz cloud-config-url=${cloud-config-url}
    initrd ${base-url}/flatcar_production_pxe_image.cpio.gz
    boot
    

    The Beta channel consists of promoted Alpha releases. The current version is Flatcar Container Linux 3850.1.0.

    A sample script will look like this:

    #!ipxe
    
    # Location of your shell script.
    set cloud-config-url http://example.com/cloud-config-bootstrap.sh
    
    set base-url https://beta.release.flatcar-linux.net/amd64-usr/current
    kernel ${base-url}/flatcar_production_pxe.vmlinuz cloud-config-url=${cloud-config-url}
    initrd ${base-url}/flatcar_production_pxe_image.cpio.gz
    boot

    The Stable channel should be used by production clusters. Versions of Flatcar Container Linux are battle-tested within the Beta and Alpha channels before being promoted. The current version is Flatcar Container Linux 3815.2.0.

    A sample script will look like this:

    #!ipxe
    
    # Location of your shell script.
    set cloud-config-url http://example.com/cloud-config-bootstrap.sh
    
    set base-url https://stable.release.flatcar-linux.net/amd64-usr/current
    kernel ${base-url}/flatcar_production_pxe.vmlinuz cloud-config-url=${cloud-config-url}
    initrd ${base-url}/flatcar_production_pxe_image.cpio.gz
    boot

    Go to My Servers > Startup Scripts > Add Startup Script, select type “PXE”, and input your script. Be sure to replace the cloud-config-url with that of the shell script you created above.

    Additional reading can be found at Booting Flatcar Container Linux with iPXE and Embedded scripts for iPXE .

    Create the VPS

    Create a new VPS (any server type and location of your choice), and then:

    1. For the “Operating System” select “Custom”
    2. Select “iPXE Custom Script” and the script you created above.
    3. Click “Place Order”

    Once you receive the “Subscription Activated” email the VPS will be ready to use.

    Accessing the VPS

    You can now log in to Flatcar Container Linux using the associated private key on your local computer. You may need to specify its location using -i LOCATION. If you need additional details on how to specify the location of your private key file see here .

    SSH to the IP of your VPS, and specify the “core” user: ssh core@IP

    $ ssh core@IP
    The authenticity of host 'IP (2a02:1348:17c:423d:24:19ff:fef1:8f6)' can't be established.
    RSA key fingerprint is 99:a5:13:60:07:5d:ac:eb:4b:f2:cb:c9:b2🆎d7:21.
    Are you sure you want to continue connecting (yes/no)? yes
    Warning: Permanently added '[IP]' (ED25519) to the list of known hosts.
    Enter passphrase for key '/home/user/.ssh/id_rsa':
    Flatcar Container Linux stable (557.2.0)
    core@localhost ~ $
    

    Using Flatcar Container Linux

    Now that you have a machine booted it is time to play around. Check out the Flatcar Container Linux Quickstart guide or dig into more specific topics .