.. _Creating Linux Templates:

Creating Linux Templates
------------------------

If you do not have a ready Linux template, you can build one with the ``diskimage-builder`` tool. The disk image is created with only the root user that has neither password nor SSH keys. You can use the ``user data`` and ``cloud-init`` methods to perform initial configuration tasks on VMs that will be deployed from the disk image, for example, create custom user accounts. For more options to customize a VM during boot, refer to the `cloud-init documentation <https://cloudinit.readthedocs.io/en/latest/index.html>`__.

To create a template and deploy a VM from it, do as follows:

#. Install the ``diskimage-builder`` package:

   ::

       # yum install diskimage-builder

#. For the RHEL 7 guest OS, download the cloud image from the `Red Hat Customer Portal <https://access.redhat.com/downloads/content/69/ver=/rhel—7/7.1/x86_64/product-downloads>`__ (login required) and execute:

   ::

       # export DIB_LOCAL_IMAGE=<path_to_rhel7_image>

#. Execute the following command to build a disk image with installed ``cloud-init`` for the desired Linux guest. For example:

   ::

       # disk-image-create vm centos7 -t qcow2 -o centos7

   where

   - ``centos7`` is the name of a guest OS. Can be one of the following: ``centos6``, ``centos7``, ``debian``, ``rhel7``, or ``ubuntu``. 

     By default, using the ``ubuntu`` element will create a disk image for Ubuntu 16.04. To build the Ubuntu 18.04 disk image, add the ``DIB_RELEASE=bionic`` to the command as follows: ``DIB_RELEASE=bionic disk-image-create vm ubuntu -t qcow2 -o ubuntu18``.

   - ``-o`` sets the name for the resulting disk image file.

#. Upload the created disk image using the ``vinfra`` tool to the compute cluster:

   ::

       # vinfra service compute image create centos7-image --os-distro centos7 \
       --disk-format qcow2 --file centos7.qcow2

   where 

   - ``centos7-image`` is the name of a new image.

   - ``centos7`` is the corresponding OS version. Can be one of the following: ``centos6``, ``centos7``, ``debian9``, ``rhel7``, ``ubuntu16.04``, and ``ubuntu18.04``.

   - ``centos7.qcow2`` is the QCOW2-image created on step 3.

#. Create the ``user-data`` configuration file with a custom user account:

   ::

       # cat <<EOF > user-data
       #cloud-config

       users:
         - name: user
           lock-passwd: false
           sudo: ALL=(ALL) NOPASSWD:ALL
           passwd: $6$CjI58V.q7gFvBlMU$9lvue5t8l/VD/tR9L8VTgaRnIksr7ZkSvjtxGxAelJaa.\
       WWAmJwRKLjbJwjikOSO2P5DCEYSX/Uf.MuvvhrCE/
       EOF

   where ``user`` is the name of a custom user and ``$6$CjI58V<...>`` is a hashed password for the account.

#. Launch the deployment of a VM from the disk image using the configuration file as user data:

   ::

       # vinfra service compute server create centos7-vm --flavor medium --network public \
       --user-data user-data --volume source=image,id=centos7-image,size=10

   where 

   - ``centos7-vm`` is the name of a new VM,

   - ``user-data`` is the configuration file created in step 5, 

   - ``centos7-image`` is the image added to the compute cluster in step 4.
       
   For more information on using the ``vinfra`` tool, see *Command Line Reference*.