Using the Hosts API¶
Here we will assume that we already have a
Client instance configured with the appropriate
authentication method (as demonstrated in Authenticating to Craton).
Listing Hosts¶
The Hosts API implements pagination. This means that by default, it does not return all hosts known to Craton. To ignore page limits and offsets, we can allow cratonclient to do handle pagination for us:
for host in craton.hosts.list():
print_host_info(host)
By default list() will handle
pagination for you. If, instead, you want to handle it yourself you will want
to do something akin to:
first_page_of_hosts = list(craton.hosts.list(autopaginate=False))
marker_id = first_page_of_hosts[-1].id
second_page_of_hosts = list(craton.hosts.list(
autopaginate=False,
marker=marker_id,
))
marker_id = second_page_of_hosts[-1].id
third_page_of_hosts = list(craton.hosts.list(
autopaginate=False,
marker=marker_id,
))
# etc.
A more realistic example, however, might look like this:
hosts_list = None
marker = None
while hosts_list and hosts_list is not None:
hosts_list = list(craton.hosts.list(
marker=marker,
autopaginate=False,
))
# do something with hosts_list
if hosts_list:
marker = hosts_list[-1].id
This will have the effect of stopping the while loop when you eventually
receive an empty list from craton.hosts.list(...).
Creating Hosts¶
Hosts live inside either a Region or Cell in Craton. To create a host, one needs:
- A unique name
- A unique IP address
- A “device type” (this is freeform), e.g., “server”, “container”, “nova-vm”, etc.
- A cloud ID
- A region ID
host = craton.hosts.create(
name='my-host-0',
ip_address='127.0.1.0',
device_type='server',
cloud_id=cloud_id,
region_id=region_id,
note='This is my host, there are many like it, but this is mine.',
variables={
'some-var': 'some-var-value',
},
)
Using a Host’s Variables¶
Once we have a host we can introspect its variables like so:
host = craton.hosts.get(host_id)
host_vars = host.variables.get()
To update them:
updated_vars = {
'var-a': 'new-var-a',
'var-b': 'new-var-b',
'updated-var': 'updated value',
}
host.variables.update(**updated_vars)
To delete them:
host.variables.delete('var-a', 'var-b', 'updated-var')
Updating a Host¶
We can update a host’s attributes (but not its variables) like so:
craton.hosts.update(
host_id,
name='new name',
note='Updated note.',
)
Most attributes that you can specify on creation can also be specified for updating the host as well.