Welcome to RAX-AutoScaler’s documentation!¶

RAX-AutoScaler use the rackspace APIs to allow for scaling based on aggregate metrics across a cluster. Can be used and installed on the auto-scale group members or on a dedicated management instance.

GitHub repository: https://github.com/boxidau/rax-autoscaler
PyPI package: https://pypi.python.org/pypi/rax-autoscaler
Stories in Ready: https://badge.waffle.io/boxidau/rax-autoscaler.svg?label=ready&title=Ready)](http://waffle.io/boxidau/rax-autoscaler

Contents:

Quick Start¶

Installation¶

pip install RAX-AutoScaler

Configuration¶

Edit config.json adding the following: * API username * API key * Region name * Autoscaling group section should contain:

AutoScale Group UUID

Scale Up Policy UUID

Scale Down Policy UUID

Check Type (agent.cpu, agent.load_average...)

Metric Name (depends on the check type)

Scale Up Threshold

Scale Down Threshold

Webhooks Url (Pre & Post commit url(s) for scale up/down)

Usage¶

Once configured you can invoke the autoscaler.py script.

–cluster option should be used when this script actually runs on auto-scale group members. Otherwise if it is running on a dedicated management instance you do not require this option.

–as-group option should be used when you have multiple groups listed in the config.json file.

–config-file option should be used if config.json file does not exists in current directory or in ‘/etc/rax-autoscaler’ path.

Once tested you should configure this script to run as a cron job either on a management instance or on all cluster members

Cloud Init¶

You can use the cloud-config file to auto-install RAX-Autoscaler on new servers. For example to do so on Rackspace cloud using supernova

supernova <region> boot –user-data ./cloud-config –image <image id/name> –flavor <flavor id/name> –config-drive=true <server name>

To use this with autoscale you would want to set the userdata of your launch configuration to the base64 encoded string of the file:

"launchConfiguration": {
      "args": {
          "server": {
              "config_drive" : true,
              "flavorRef": "general1-1",
              "imageRef": "CentOS 6.5 (PVHVM)",
              "key_name" : "MY_SSH_KEY",
              "user_data" : "I2Nsb3VkLWNvbmZpZwoKcGFja2FnZXM6CiAgLSBweXRob24tcGlwCgpydW5jbWQ6CiAgLSBbIHBpcCwgaW5zdGFsbCwgUkFYLUF1dG9TY2FsZXIgXQo=",
              "name": "test-autoscale"
          }
      },
      "type": "launch_server"
  }

This has been tested on these images:

Ubuntu 14.04 LTS (PVHVM)
CentOS 6.5 (PVHVM)

In the example the value of user_data contains the base64 encoded version of the following script:

echo -n "I2Nsb3VkLWNvbmZpZwoKcGFja2FnZXM6CiAgLSBweXRob24tcGlwCgpydW5jbWQ6CiAgLSBbIHBpcCwgaW5zdGFsbCwgUkFYLUF1dG9TY2FsZXIgXQo=" | base64 -D

To base64 encode a script :: cat /path/to/USER_DATA | base64

Size of USER_DATA can be reduced with gzip: :: cat /path/to/USER_DATA | gzip | base64

Note¶

RAX-AutoScaler depends on Rackspace Monitoring Agent to get the data from nodes in scaling group.

If the agent is not installed please read: Install the Cloud Monitoring Agent: http://www.rackspace.com/knowledge_center/article/install-the-cloud-monitoring-agent

Contributing¶

Fork it
Create your feature branch (git checkout -b my-new-feature)
Commit your changes (git commit -am ‘Add some feature’)
Push to the branch (git push origin my-new-feature)
Create new Pull Request

What is Sphinx?¶

Sphinx is a tool that helps to generate python documentation. Features:

Output formats: HTML (including Windows HTML Help), LaTeX (for printable PDF versions), ePub, Texinfo, manual pages, plain text

Extensive cross-references: semantic markup and automatic links for functions, classes, citations, glossary terms and similar pieces of information

Hierarchical structure: easy definition of a document tree, with automatic links to siblings, parents and children

Automatic indices: general index as well as a language-specific module indices

Code handling: automatic highlighting using the Pygments highlighter

Quick start¶

You can add inline comments about a function or class at the begining for example:

def exit_with_error(msg):
    """This function prints error message and exit with error.

    :param msg: error message
    :type name: str
    :returns: 1 (int) -- the return code

    """

Execute make command in project directory with doc arg:

make doc

After successful execution updated .html file sould be available here ‘docs/_build/html/’

autoscale.autoscale(group, config_data, args)[source]¶

This function executes scale up or scale down policy

Parameters:	group – group name config_data – json configuration data args – user provided arguments

autoscale.exit_with_error(msg)[source]¶

This function prints error message and exit with error.

Parameters:	msg – error message
Returns:	1 (int) – the return code

autoscale.get_scaling_group(group, config_data)[source]¶

This function checks and gets active servers in scaling group

Parameters:	group – group name config_data – json configuration data
Returns:	scalingGroup if server state is active else null

autoscale.is_node_master(scalingGroup)[source]¶

This function checks scaling group state and determines if node is a master.

Parameters:	scalingGroup – data about servers in scaling group retrieve from cloudmonitor
Returns:	1 : if cluster state is unknown 2 : node is a master None : node is not a master

autoscale.main()[source]¶: This function validates user arguments and data in configuration file. It calls auth class for authentication and autoscale to execute scaling policy

common.check_file(fname)[source]¶

This function checks if file exists and is readable.

Parameters:	fname – file name
Returns:	file name with absolute path

common.get_config(config_file)[source]¶

This function read and returns jsons configuration data

Parameters:	config_file – json configuration file name
Returns:	json data

common.get_group_value(config, group, key)[source]¶

This function returns value in autoscale_groups section associated with: provided key.

common.get_logger()[source]¶

This function instantiate the logger.

Returns:	logger

common.get_machine_uuid()[source]¶

This function uses subprocess to get node uuid and cached it for future use

Returns:	server uuid None

common.get_user_value(args, config, key)[source]¶

This function returns value associated with the key if its available in: user arguments else in json config file.

Parameters:	args – user arguments config – json configuration data key – key name
Returns:	value associated with key

common.get_webhook_value(config, group, key)[source]¶

This function returns value in webhooks section of json file which is: associated with provided key.

Parameters:	group – group name config – json configuration data key – key name
Returns:	value associated with key

common.webhook_call(config_data, group, policy, key)[source]¶

This function makes webhook calls.

Parameters:	config_data – json configuration data group – group name policy – policy type key – key name

class auth.Auth(username, apikey, region, identity_type='rackspace', token_filename='/home/docs/.rax-autoscaler-token')[source]¶

This class implements Rackspace cloud account authentication

authenticate()[source]¶

This method loads a token from a file, authenticate with it, and if it fails then tries to authenticate with credentials

Returns:	True or False (Boolean)

authenticate_credentials()[source]¶

This method try to authenticate with available credentials

Returns:	True or False (Boolean)

authenticate_token()[source]¶

This authenticate with Rackspace cloud using existing token.

Returns:	True or False (Boolean)

force_unauthenticate()[source]¶: This unauthenticate and delete token file

load_token()[source]¶

This loads token from a file

Returns:	True or False (Boolean)

save_token()[source]¶

This saves token to a file

Returns:	True or False (Boolean)

status()[source]¶

This queries pyrax for values

Returns:	list – the return value

token_filename[source]¶

This returns token filename

Returns:	_token_filename

cloudmonitor.add_cm_check(server_id, check_type, check_config)[source]¶

This function adds Cloud Monitoring cpu check to a server,: if it is not already present

Parameters:	server_id – server identity
Returns:	int – the return code 1 – Success

cloudmonitor.get_entity(agent_id)[source]¶

This function get entity for passed agent_id (agent_id := server_uuid)

Parameters:	agent_id – agent id

cloudmonitor.get_server(server_id)[source]¶: It gets Cloud server object by server_id

cloudmonitor.get_server_ipv4(server_id, _type='public')[source]¶

It gets public IP v4 server address

Parameters:	server_id – server id

cloudmonitor.get_server_name(server_id)[source]¶

It returns the name of a server, using cached values

Parameters:	server_id – server id
Returns:	d_cached_servers_name[server_id] (str)

cloudmonitor.is_ipv4(address)[source]¶: It checks if address is valid IP v4

cloudmonitor.scaling_group_servers(sgid)[source]¶

list servers’ id in scaling group sgid

Parameters:	sgid – scaling group id

class colouredconsolehandler.ColouredConsoleHandler(stream=None)[source]¶

console handler with ANSI colours support Usage example:

def white_bold_underlined(self, msg):

return self.decorate(self.BOLD + self.UNDERLINE +

self.COLOR[‘white’], msg)

ref: http://cwoebker.com/posts/ansi-escape-codes

Indices and tables¶

License¶

Licensed under the Apache License, Version 2.0 (the “License”); you may not use this file except in compliance with the License. You may obtain a copy of the License at

http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an “AS IS” BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.