Install a custom kernel¶

You can install a custom kernel in a bootstrap image. For example, you can install the latest Ubuntu kernel or an older version of the kernel intended to fix regressions.

Install the latest kernel¶

To install the latest lts-trusty kernel, you do not need to make any customization. Simply run the bootstrap builder with the default parameters and the latest lts-trusty kernel available in the repositories will be fetched.

To install the latest kernel:

1. Install the kernel different from lts-trusty

2. Open and edit configuration file adding the new repository:

   $ vim /etc/fuel-bootstrap-cli/fuel_bootstrap_cli.yaml
   

   ...
   - name: wily1
     priority: 1001
     section: "main restricted universe multiverse"
     suite: wily
     type: deb
     uri: "http://cz.archive.ubuntu.com/ubuntu/"
   - name: wily2
     priority: 1001
     section: "main restricted universe multiverse"
     suite: wily-updates
     type: deb
     uri: "http://cz.archive.ubuntu.com/ubuntu/"
   ...
   

3. Build and activate a bootstrap image specifying a kernel flavor:

   $ fuel-bootstrap --verbose --debug build --label 'with_wily_kernel' --activate --kernel-flavor linux-image-generic-lts-wily
   

4. Reboot the discovered node:

   $ ssh 10.109.0.3
   

5. Verify if the node applied the kernel succesfully:

   1. View infomation about the installed kernel image:

      # dpkg -l | grep wily
      

      System response:

      ii  linux-image-generic-lts-wily       4.2.0.27.21  amd64   Generic Linux kernel image
      

   2. View infomation about the current kernel:

      # uname  -a
      

      System response:

      Linux bootstrap 4.2.0-27-generic #32~14.04.1-Ubuntu SMP Fri Jan 22 15:32:26 UTC 2016 x86_64 x86_64 x86_64 GNU/Linux
      

Install an old kernel¶

For code stability, security, or other reasons, you may not want to install the latest kernel as described above.

To install an old version of kernel:

1. Verify the version of lts-vivid meta-package:

   apt-cache show linux-image-generic-lts-vivid | grep -i Depends
   

   Example of system response:

   Depends: linux-image-3.19.0-47-generic, linux-image-extra-3.19.0-47-generic, linux-firmware
   

2. Prepare a bash script with the kernel version you want to install. For example:

   $ cat /root/user_script.sh
   

   System response:

   #!/bin/bash
   
   echo "START user-script"
   apt-get remove -y linux-image-generic-lts* linux-image-*
   apt-get purge -y linux-image-generic-lts* linux-image-*
   
   rm -f /boot/vmlinuz*
   rm -f /boot/initrd*
   
   apt-get install -y linux-image-3.19.0-25-generic linux-image-extra-3.19.0-25-generic
   echo "END user-script"
   

   This bash script installs the linux-image-3.19.0-25-generic kernel.

3. Build and activate a bootstrap image including the custom script you created before:

   $ fuel-bootstrap build --verbose --debug --activate --label 'old_kernel' --script /root/user_script.sh
   

   System response:

   ...
   Copy user-script /root/user_script.sh into chroot:/tmp/tmplGugKE.fuel-agent-image
   Make user-script /tmp/tmplGugKE.fuel-agent-image/user_script.sh executable
   Trying to execute command: chroot /tmp/tmplGugKE.fuel-agent-image /bin/bash -c /user_script.sh
   ...
   Bootstrap image 244782c1-7343-43f7-9ee3-8989c252eb2e has been built
   ...
   Bootstrap image 244782c1-7343-43f7-9ee3-8989c252eb2e has been activated.
   

4. Reboot the discovered node:

   $ ssh 10.109.0.3
   

5. Verify if the node applied the kernel succesfully:

   1. View infomation about the current kernel:

      # uname  -a
      

      System response:

      Linux bootstrap 3.19.0-25-generic #26~14.04.1-Ubuntu SMP Fri Jul 24 21:16:20 UTC 2015 x86_64 x86_64 x86_64 GNU/Linux
      

   2. View infomation about the installed kernel image:

      # dpkg -l | grep image
      

      System response:

      ii  linux-image-3.19.0-25-generic  3.19.0-25.26~14.04.1  amd64  Linux kernel image for version 3.19.0 on 64 bit x86 SMP
      ii  linux-image-extra-3.19.0-25-generic 3.19.0-25.26~14.04.1   amd64  Linux kernel extra modules for version 3.19.0 on 64 bit x86 SMP
      

   3. Verify that the runtime_uuid value of the activated bootstrap image has been updated in the nailgun-agent configuration file:

      # cat /etc/nailgun-agent/config.yaml
      

      System response:

      {runtime_uuid: 244782c1-7343-43f7-9ee3-8989c252eb2e}