Agent Packager

The Cloudify agent is basically a virtualenv in which a series of modules are installed and (optionally) to which a some configuration files are attached.

To use Cloudify with distributions other than the officially supported ones, an Agent Packager tool is provided to assist you to create agents for your distributions.

The purpose of the tool is to:

• Address the issues related to compiling module requirements on different distributions, by bridging the gap between user-compiled images, unfamiliar/minor distributions, and so on.
• Enable you to create your own Cloudify agents with your custom plugins.
• Make the agent creation process seamless in terms of there being a single configuration file and a single-line command.
• Enable you to override existing mandatory (and other) modules, by providing your own.

You can use the Cloudify agent packager to create an agent on the distribution on which you are running, that uses your distribution and compilers for modules that require compilation.

Creation Process

During the creation process, the agent-packager performs the following actions:

• Creates a virtualenv using your selected Python binary.
• Installs mandatory external modules into the virtualenv.
• Installs modules from a provided requirements.txt file.
• Installs mandatory and optional Cloudify plugins and modules into the virtualenv.
• Installs the cloudify-agent module into the virtualenv.
• Installs any additional user-selected Cloudify plugins and Python modules into the virtualenv.
• Validates that all specified modules are installed.
• Generates an included_plugins.py file. The file is used by the cloudify-agent module to automatically load all plugins specified in the file.
• Creates a TAR file containing the virtualenv.

Installation

pip install cloudify-agent-packager

For development purposes:

pip install https://github.com/cloudify-cosmo/cloudify-agent-packager/archive/master.tar.gz

Usage

IMPORTANT NOTES:

• You must use this tool on the specific version of the distribution on which you intend your agent to run, as it might require compilation.
• You must have the required version of Python installed on your selected image.
• You must have the tar binary in your distribution (run which tar to verify that you have TAR installed).

Creating the Agent Packager from the CLI

To create the agent packager from the CLI, do the following:

cfy-ap -h

Script to run Cloudify's Agent Packager via command line

Usage:
    cfy-ap [--config=<path> --force --dryrun --no-validation -v]
    cfy-ap --version

Options:
    -h --help                   Show this screen
    -c --config=<path>          Path to config yaml (defaults to config.yaml)
    -f --force                  Forces deletion and creation of venv and tar file.
    -d --dryrun                 Lists the modules to be installed without actually installing them.
    -n --no-validation          Does not validate that all modules were installed correctly.
    -v --verbose                Verbose level logging
    --version                   Displays current version

example:

cfy-ap -f -c my_config.yaml -v

Creating the Agent Packager from Python

To create the agent packager from Python, do the following:

import agent_packager.packager as cfyap

config = {}  # dict containing the configuration as given in the yaml file.

cfyap.create(config=config,
             config_file=None,
             force=False,
             dryrun=False,
             no_validate=False,
             verbose=True)

The cloudify-agent Module

See here.

Using the Agent

After creating the agent you can do one of the following:

Use the Agent on a Per-Node Basis

You can define the paths to the agent TAR file in a blueprint on a per-node basis. See the cloudify-agent documentation for more information.

Install Agents in Cloudify Manager during Bootstrap

You can provide URLs for agents that you want to provide during Cloudify Manager bootstrap.

Configuring the Tool

The YAML Configuration File

Following is an example configuration file.

distribution: Ubuntu
release: trusty
python_path: '/usr/bin/python'
requirements_file: path/to/my/requirements/file.txt
cloudify_agent_version: master
cloudify_agent_module: http://github.com/cloudify-cosmo/cloudify-agent/archive/master.tar.gz
core_modules:
    cloudify_plugins_common: http://github.com/cloudify-cosmo/cloudify-plugins-common/archive/master.tar.gz
    cloudify_rest_client: http://github.com/cloudify-cosmo/cloudify-rest-client/archive/master.tar.gz
core_plugins:
    cloudify_script_plugin: http://github.com/cloudify-cosmo/cloudify-script-plugin/archive/master.tar.gz
additional_modules:
    - pyyaml==3.12
additional_plugins:
    cloudify_fabric_plugin: http://github.com/cloudify-cosmo/cloudify-fabric-plugin/archive/master.tar.gz
output_tar: Ubuntu-trusty-agent.tar.gz
keep_virtualenv: true

Explanation of the Configuration YAML File

python -c "import platform; print platform.dist()"
# e.g. ('Ubuntu', '14.04', 'trusty')

• distribution - The distribution for which the agent is intended. If this is omitted, the tool attempts to retrieve the distribution by itself. The distribution is then used to name the virtualenv (unless explicitly specified in venv) and to name the output file (unless explicitly specified in output_tar).
• release - The release (e.g. precise, trusty) of the distribution for which the agent is intended. If this is omitted, the tool will attempt to retrieve the release by itself. The release is then used to name the virtualenv (unless explicitly specified in venv) and to name the output file (if unless specified in `output_tar’).
• python_path - Enables you to set the Python binary to be used when creating venv. (Defaults to /usr/bin/python).
• requirements_file - Path to the requirements.txt file that contains the modules you want to be installed in the agent.
• cloudify_agent_version - Specifies the version of the cloudify-agent module to install (Not required if cloudify_agent_module is specified). Note that this can be used to create an agent for a specific Cloudify version.
• cloudify_agent_module - Specifies the URL from which the cloudify-agent module is to be installed. (Ignores cloudify_agent_version, if specified).
• core_modules - A dict of core modules to install into the virtualenv. (If omitted or with a value of false, the module is installed as a part of the cloudify-agent dependencies.) See a list of current core modules below.
• core_plugins - A dict of core plugins to install into the virtualenv. (If omitted or with a value of false, the module is installed as a part of the cloudify-agent dependencies.) See a list of core plugins below. If exclude is set (per module), it is not installed. Set exclude with extra care.
• additional_modules - A list of additional modules to install into the virtualenv. You can add any additional modules that are not Cloudify plugins here.
• additional_plugins - A list of additional Cloudify plugins to install into the virtualenv.
• output_tar - Path to the TAR file you want to create.
• keep_virtualenv - Specifies whether to keep the virtualenv after creating the TAR file. Default is false.

Agent Modules

Each agent contains a set of Python packages. These modules can be either simple Python libraries, or plugins.

Core External Modules:

These are modules, which are not developed by Cloudify, that are used by the agent.

• Pika (Mandatory)

Core Modules

These modules are developed by Cloudify and provide core functionality for the agent. The default agents provided with Cloudify come with these modules pre-installed.

• Cloudify REST Client (Mandatory)
• Cloudify Plugins Common (Mandatory)

Core Plugins

These plugins are developed by Cloudify and provide core functionality for the agent. The default agents provided with Cloudify come with these modules pre-installed.

• Cloudify Script Plugin (Optional)

The Cloudify Manager also runs an instance of an agent, which is called the cloudify_management_agent. This agent is responsible for starting all other agents, and therefore requires the following plugin.

• Cloudify Agent