cloudbridge/docs/topics/launch.rst

Launching instances
===================
Before being able to run below commands, you will need a ``provider`` object
(see `this page <setup.html>`_).

Common launch data
------------------
Before launching an instance, you need to decide what image to launch
as well as what type of instance. We will create those objects here. The
specified image ID is a base Ubuntu image on AWS so feel free to change it as
desired. For instance type, we're going to let CloudBridge figure out what's
the appropriate name on a given provider for an instance with at least 2 CPUs
and 4 GB RAM.

.. code-block:: python

    img = provider.compute.images.get('ami-f4cc1de2')  # Ubuntu 16.04 on AWS
    inst_type = sorted([t for t in provider.compute.instance_types.list()
                        if t.vcpus >= 2 and t.ram >= 4],
                       key=lambda x: x.vcpus*x.ram)[0]

When launching an instance, you can also specify several optional arguments
such as the security group, a key pair, or instance user data. To allow you to
connect to the launched instances, we will also supply those parameters (note
that we're making an assumption here these resources exist; if you don't have
those resources under your account, take a look at the
`Getting Started <../getting_started.html>`_ guide).

.. code-block:: python

    kp = provider.security.key_pairs.find(name='cloudbridge_intro')[0]
    sg = provider.security.security_groups.list()[0]

Launch an instance
------------------
Once we have all the desired pieces, we'll use them to launch an instance:

.. code-block:: python

    inst = provider.compute.instances.create(
        name='CloudBridge-VPC', image=img, instance_type=inst_type,
        key_pair=kp, security_groups=[sg])

Private networking
~~~~~~~~~~~~~~~~~~
Private networking gives you control over the networking setup for your
instance(s) and is considered the preferred method for launching instances. To
launch an instance with an explicit private network, supply a subnet within
a network as an additional argument to the ``create`` method:

.. code-block:: python

    provider.network.list()  # Find a desired network ID
    net = provider.network.get('desired network ID')
    sn = net.subnets()[0]  # Get a handle on the desired subnet to launch with
    inst = provider.compute.instances.create(
        name='CloudBridge-VPC', image=img, instance_type=inst_type,
        subnet=sn, key_pair=kp, security_groups=[sg])

For more information on how to create and setup a private network, take a look
at `Networking <./networking.html>`_.

Block device mapping
~~~~~~~~~~~~~~~~~~~~
Optionally, you may want to provide a block device mapping at launch,
specifying volume or ephemeral storage mappings for the instance. While volumes
can also be attached and mapped after instance boot using the volume service,
specifying block device mappings at launch time is especially useful when it is
necessary to resize the root volume.

The code below demonstrates how to resize the root volume. For more information,
refer to :class:`.LaunchConfig`.

.. code-block:: python

    lc = provider.compute.instances.create_launch_config()
    lc.add_volume_device(source=img, size=11, is_root=True)
    inst = provider.compute.instances.create(
        name='CloudBridge-BDM', image=img,  instance_type=inst_type,
        launch_config=lc, key_pair=kp, security_groups=[sg])

where ``img`` is the :class:`.Image` object to use for the root volume.

After launch
------------
After an instance has launched, you can access its properties:

.. code-block:: python

    # Wait until ready
    inst.wait_till_ready()  # This is a blocking call
    inst.state
    # 'running'

Depending on the provider's networking setup, it may be necessary to explicitly
assign a floating IP address to your instance. This can be done as follows:

.. code-block:: python

    # List all the IP addresses and find the desired one
    provider.network.floating_ips()
    # Assign the desired IP to the instance
    inst.add_floating_ip('149.165.168.143')
    inst.refresh()
    inst.public_ips
    # [u'149.165.168.143']