Guides - Manage Configuration Profiles on a Compute Instance

A configuration profile functions as a boot loader for a Compute Instance. It controls general boot settings, including the disk the instance will boot from, the disks that will be mounted, the kernel that will be used, and the network interfaces on the instance. Multiple configuration profiles can be created, each one booting from different disks with different settings. This can allow you to try out new Linux distributions without paying for additional Compute Instances (see Deploy an Image to a Disk on an Existing Compute Instance) or to create custom software testing environments.

View Configuration Profiles

The configuration profiles for a Compute Instance can be viewed and managed from the Cloud Manager.

1. Log in to the Cloud Manager, click the Linodes link in the sidebar, and select a Compute Instance from the list.

2. Navigate to the Configurations tab to view the configuration profiles on a Compute Instance.

From here, a configuration profile can be created using the Add Configuration button. To take action on an certain configuration, locate it within the Configurations table and select from the list of actions, some or all of which may appear within the ellipsis menu:

• Boot: Boots the Compute Instance using the settings defined within the selected configuration profile. See Booting from a Configuration Profile.
• Edit: Modify the settings within a configuration profile. See Editing a Configuration Profile.
• Clone: Clones the configuration profile and the attached disks to any Compute Instance on the same account. See Cloning a Configuration Profile and the Attached Disks.
• Delete: Deletes the configuration profile. See Deleting a Configuration Profile.

Settings

When adding or editing a configuration profile on a Compute Instance, the following settings are available:

• Virtual Machine: VM mode determines whether devices inside your virtual machine are paravirtualized or fully virtualized. Here are the drivers used for various devices in each mode:

  Device	Paravirtualization	Full virtualization
  Block	VirtIO SCSI	IDE
  Network	VirtIO Net	e1000
  Serial	ttyS0	ttyS0

  Since paravirtualization offers more performant networking and disk IO, it is the recommended mode. All Linux distributions provided by Linode support paravirtualization. When installing an operating system not offered by Linode, full virtualization may be required if that OS does not include virtualization-aware drivers.

• Boot Settings:

  • Kernel: Select the version of the Linux kernel that will be used. The options include Grub 2 (for upstream or custom-compiled kernels), a specific Linode supplied kernel, or Direct Disk. For most distributions, its recommended to set this option to Grub 2. See Manage the Kernel on a Compute Instance.
  • Run Level: Adjust the run level of the OS to allow for advanced diagnostics. Recommended setting: Run Default Level.
  • Memory Limit: Limits the amount of memory that the Compute Instance can use. Recommended setting: Do not set any limits on memory usage.

• Block Device Assignment: Assigns the Compute Instance’s disks to the disk devices in Linux, making them accessible once the instance has booted up. Up to 8 disks can be assigned (/dev/sda through /dev/sdg), though it’s common to only use the first two devices: /dev/sda as the main disk and /dev/sdb as the swap disk. The Root Device is used to select the primary disk device (commonly /dev/sda), though another predefined device or custom device path can be used.

  Note

  In some Linode distribution images, block devices are assigned using UUIDs in the /etc/fstab file to support proper disk mounting. In order to see the UUID assigned to each block device, you can use the lsblk command:

  lsblk -f

  This displays block devices for your booted configuration and their current mount points:

  NAME FSTYPE FSVER LABEL       UUID                                 FSAVAIL FSUSE% MOUNTPOINTS
  sda  ext4   1.0   linode-root cfa3834a-c6ec-0c85-1b68-6345a69f3759   14.3G    20% /
  sdb  swap   1                 208b24eb-47fe-4e6b-907a-d70d24af0cf0                [SWAP]
  sdc  ext4   1.0   linode-root 72a6eb6d-941c-bf66-c5e7-636242a1efbe

• Network Interfaces: Assigns either a VLAN or the Public Internet to a network interface in Linux. There are a total of 3 available network interfaces: eth0, eth1, and eth2. If no VLANs are in use, the recommended setting is Public Internet for eth0 and None for all other interfaces. See Getting Started with VLANs.

• Filesystem / Boot Helpers: Various helper tasks that run when the Compute Instance is booted up. Recommended setting for all helpers: Enabled.

  • Enable distro helper: Helps maintain correct inittab/upstart console device.
  • Disable updatedb: Disables updatedb cron job to avoid disk thrashing.
  • Enable modules.dep helper: Creates a module dependency file for the kernel you run.
  • Auto-mount devtmpfs: Controls if pv_ops kernels auto-mount devtmpfs at boot.
  • Auto-configure networking: Automatically configures static networking. See Network Helper.

Create a Configuration Profile

Making a new configuration profile allows you to create a new and separate boot configuration for your system. You can specify boot settings and disks to mount. Here’s how to create a new configuration profile:

1. Within the Cloud Manager, view the Configuration Profiles for your desired Compute Instance. See View Configuration Profiles.

2. Select the Add a Configuration link. The Add Configuration form appears:

3. Enter the Label for the new configuration, as well as an optional Comment.

4. Complete the remainder of the form, referencing the Settings section above for additional details and recommended values. For most basic configurations, it’s recommended to adjust the following settings:

   • Kernel: Select Grub 2.
   • Block Device Assignments: Set /dev/sda to the disk you want to use as the primary disk (and boot disk) and set /dev/sdb to the swap disk.

5. Click Add Configuration to create the new configuration profile.

Edit a Configuration Profile

You can edit existing configuration profiles to change boot settings, set other disks to mount, and more. Here’s how to edit a configuration profile:

1. Within the Cloud Manager, view the Configuration Profiles for your desired Compute Instance. See View Configuration Profiles.

2. Within the Configurations table, locate the configuration profile you wish to modify and click the corresponding Edit button, which may also appear within the ellipsis menu. This displays the Edit Configuration form.

3. Adjust any settings as needed, referencing the Settings section above for additional details and recommended values.

4. Once finished, click Save Changes.

The changes to the configuration profile have been saved. You may need to reboot your Compute Instance to activate the changes.

Boot from a Configuration Profile

You can create and store many different configuration profiles in the Cloud Manager, but you can only boot your Compute Instance from one configuration profile at a time. Here’s how to select a configuration profile and boot your instance from it:

1. Within the Cloud Manager, view the Configuration Profiles for your desired Compute Instance. See View Configuration Profiles.

2. Within the Configurations table, locate the configuration profile you wish to modify and click the corresponding Boot button, which may also appear within the ellipsis menu.

3. A confirmation dialog window will appear. Click Boot to confirm.

4. The Compute Instance will boot (or reboot) using the selected configuration profile. The progress of the boot can be viewed from the instance’s status.

You have successfully selected and booted your Compute Instance from a configuration profile.

Determine Which Configuration Profile Was Used

When a Compute Instance is powered on or rebooted, it uses the settings stored within a configuration profile. You can determine which configuration profile was used by looking at the event history. Events are visible within the Activity Feed tab for a particular Compute Instance or within the main Events page for the account.

1. Log in to the Cloud Manager, click the Linodes link in the sidebar, and select a Compute Instance from the list.

2. Navigate to the Activity Feed tab to view all events for the instance.

3. Locate the particular boot or reboot event and review the text. The configuration profile used during that boot will be mentioned here.

   Sometimes the boot or reboot event doesn’t list a configuration profile, such as when the Lassie Shutdown Watchdog initiates the event. In this case, look at the most recent reboot or boot event which does include the configuration profile that was used.

Clone a Configuration Profile and the Attached Disks

A configuration profile, along with any attached disks, can be duplicated to any other Compute Instance on the account. See Cloning to an Existing Compute Instance for instructions.

Delete a Configuration Profile

You can remove a configuration profile from the Cloud Manager at any time. Here’s how:

1. Within the Cloud Manager, view the Configuration Profiles for your desired Compute Instance. See View Configuration Profiles.

2. Within the Configurations table, locate the configuration profile you wish to modify and click the corresponding Delete button, which may also appear within the ellipsis menu.

3. A confirmation dialog window will appear. Click Delete to confirm.

4. The Compute Instance will boot (or reboot) using the selected configuration profile. The progress of the boot can be viewed from the instance’s status.