ecommun / owncloud_ynh

servers.md 6.32 KB

Working with Servers

A server is a virtual machine instance that is managed by OpenStack Nova, the Compute service. One advantage of using OpenStack is that the virtualization layer makes it easy to create and discard servers as needed.

The Server object, generated by the Compute::server() method, is used to work with servers. You can create, update, or delete servers, and you can perform various actions on the server, such as creating a backup image, resizing it, or rebooting it.

To create an empty server:

$serv = $compute->server(); // assumes that $compute exists

To retrieve the data on an existing server:

$serv = $compute->server('9bfd203a-0695-410d-99a9-66c4194c967b');

Creating, updating, or deleting a server

Creating a new server

A server requires both a Flavor object and an Image object to be created. In addition, a server requires a name. You can easily create a new server by setting the proper values and calling the create() method:

$server = $compute->server();
$server->name = 'Small Server';
$server->flavor = $compute->flavor(2);
$server->image = $compute->image('c195ef3b-9195-4474-b6f7-16e5bd86acd0');
$server->create();

As a shortcut, you can also pass these parameters to the create() method in an associative array:

$server = $compute->server();
$server->create(array(
    'name' => 'Small Server',
    'flavor' => $compute->Flavor(2),
    'image' => $compute->Image('c195ef3b-9195-4474-b6f7-16e5bd86acd0')
));

Note that when the create() request completes, the server is not actually created. Instead, the completion of the request indicates that the server build has been initiated in the Compute instance. Server builds typically take 1-5 minutes to complete (depending upon the size of the server). However, the initial response will return the server's ID as well as the assigned root password:

// assuming we've created $server, above
printf("ID is %s, root password is %s\n",
    $server->id, $server->adminPass);

(Note: it is not recommended that you print out the root password because of security risks. This is only provided as an example.)

When you create a new server on the Rackspace public cloud, you can also associate it with one or more isolated networks. For more information, see Working with Cloud Networks.

Rebuilding an existing server

"Rebuilding" a server is nearly identical to creating one; you must supply an Image object. You can also change the server's name as part of the rebuild. The primary difference between a create and a rebuild is that, in the rebuild, the server's IP address(es) are retained (when the server is created, new IP addresses are assigned).

To rebuild a server:

$server = $compute->server('abaf0...');     // existing server
$server->rebuild(array(
    'adminPass' => 'REPLACE THIS WITH THE SERVER ROOT PASSWORD',
    'name' => 'A Bigger Server', // name is not required on rebuild
    'image' => $compute->image('c195ef3b-9195-4474-b6f7-16e5bd86acd0')));

Updating a server

The update() method is very similar to create() except that the only attributes of a server that you are permitted to update are its name and the access IP addresses.

$compute = $cloud->compute();
$server = $compute->server('908c5617-26c2-4535-99a9-3f20e4b74835');
$server->update(array('accessIPv4'=>'50.57.94.244'));

Deleting a server

The delete() method is short and sweet: it immediately initiates the deletion of the server. Note that this is a destructive mechanism and it is unlikely that the server can be recovered. Example:

$compute = $cloud->compute();
$server = $compute->server('908c5617-26c2-4535-99a9-3f20e4b74835');
$server->delete();  // BAM! bye-bye

Server actions

You can perform various actions on a server, such as rebooting it, resizing it, or changing the root password.

Setting the root password

Use the setPassword() method to change the root user's password:

$server->setPassword('new password');

Note that it may take a few second for the new password to take effect. Also, password restrictions (such as the minimum number of characters, numbers of punctuation characters, and so forth) are enforced by the operating system and are not always detectable by the Compute service. This means that, even though the setPassword() method succeeds, the password may not be changed, and there may not be any feedback to that effect.

To reboot the server

You can perform either a hard reboot (this is like pulling the power cord and then restarting) or a soft reboot (initiated by the operating system and generally less disruptive than a hard reboot). A hard reboot is performed by default:

$server->reboot();                                  // hard reboot
$server->reboot(ServerState::REBOOT_STATE_HARD);    // also a hard reboot
$server->reboot(ServerState::REBOOT_STATE_SOFT);    // a soft reboot

If the server is "hung," or unresponsive, a hard reboot may sometimes be the only way to access the server.

To resize the server

A server can be resized by providing a new Flavor object:

$server->resize($compute->flavor(5));

Once the resize completes (check the $server->status), you can either confirm it:

$server->resizeConfirm();

or revert it back to the original size:

$server->resizeRevert();

To rescue/unrescue a server

In rescue mode, a server is rebuilt to a pristine state and the existing filesystem is mounted so that you can edit files and diagnose issues. See this document for more details.

Put server into rescue mode:

$password = $server->rescue();

The $password is the assigned root password of the rescue server.

Take server out of rescue mode:

$server->unrescue();

This restores the server to its original state (plus any changes you may have made while it was in rescue mode).

Volumes

See Working with Volumes for information on the Server::attachVolume() and Server::detachVolume() methods.

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