Management Agent (Worker)
All VMs launched through Workload Manager or imported to Workload Manager require the Workload Manager management agent to be installed.
The agent communicates with the CloudCenter Suite cluster, either directly or through Cloud Remote, and receives instructions to perform the following tasks:
Complete application deployment tasks
Perform provisioning tasks (for example running configuration scripts)
Run custom cleanup scripts (for example to de-provision or shutdown applications)
Enforce policies (for example, to reconfigure middle ware service during auto-scaling)
Collect system metrics based on policy requirements
Monitor data, provide status updates, and keep alive system heartbeats.
Prior to the agent being installed, a set of scripts and software packages that assist with the install of the agent must be installed. This set of supporting scripts and packages is called the "worker". Once the VM has the worker installed, when the VM first boots up, the worker communicates with the bundle store to download the latest version of the agent and then start the agent. It is therefore required that the worker software have access to the Cisco hosted bundle store or a local bundle store. Also, once the agent is started, it needs access to the Cisco hosted package store or a local package store to download and start the service the VM is intended to run.
Depending on your cloud environment and application requirements there are three options for getting the worker installed on the VMs you want to launch through Workload Manager:
- Using Dynamic Bootstrapping
- Using the CentOS 6 Pre-bootstrapped Image
- Using the Worker Installer Executable
Using Dynamic Bootstrapping
The worker can be dynamically installed on VMs launched in most clouds that support an init-string passed as user data. For a matrix of which cloud providers and logical base images are supported see Dynamic Bootstrapping. This is the simplest approach to get the worker and agent installed on you deployed VMs and is recommended unless you have special requirments.
Using the CentOS 6 Pre-bootstrapped Image
- CloudCenter Suite includes a pre-bootstrapped CentOS 6 image for the clouds listed in Conditional Component Appliance Images.
- After you obtain the image (received a shared version or import the image to your cloud), you must make sure the Workload Manager CentOS 6 OOB logical image is properly mapped to the physical image via its Image ID.
- If your application services can run on CentOS 6, this may be a convenient option.
Due to licensing restriction, a pre-bootstrapped virtual appliance is not available for custom Windows images. You are required to use Install Worker on a Windows Image.
Using the Worker Installer Executable
The most flexible option for installing the worker is to run the worker installer appropriate for your OS:
Containerized OOB Services
When you manually install the worker on CentOS 7, RHEL 7, or Ubuntu 14, and select the "worker1" install option, the following Out-Of-Box (OOB) Workload Manager services will automatically run inside a Docker container inside the worker VM:
Question: Why is the Agent installed on Worker VM as part of Application deployment?
Answer: An agent is required to support on-demand actions and lifecycle actions defined in the Actions Library, service definition and application profile.
Question: How does the worker get installed on a Workload Manager deployed VM?
Answer: Two ways:
Create a pre-bootsrapped image: Use the worker installer for Linux or Windows, depending on your base OS, to manually create an image with the worker fully installed. Cisco also provides a Centos 6 pre-bootstrapped image as an appliance.
Dynamic Bootstrapping Injection: When your VM-based appliaction is launched in clouds that support an init string, Workload Manager passes an init string to the cloud provider that contains the first script needed in the worker install process. The cloud provider injects the script into the VM at deploy time. The script then executes when the VM is started and installs the worker.
Question: How does the agent communicate with the CloudCenter Suite cluster?
Answer: Once the agent is installed, it needs to connect with the AMQP service in the CloudCenter Suite cluster. If the worker VM cannot initiate this connection due to firewall restrictions, you must install Cloud Remote (Conditional).
Question: Which files are created as part of the agent installation process?
Answer: The list of file created as part of the agent installation process differs for Linux and Windows installations. See the Deployment Lifecycle Scripts > Lifecycle Action Script Definition for additional context.
Question: Why is cliqruser permission required to run some scripts?
Answer: By default, key-based authentication is configured using cliqruser permission – this user refers to the OS user in the Application VM (Worker). See the Deployment Lifecycle Scripts > Lifecycle Action Script Definition for script-specific details on when cliqruser permission is required.
Question: Why does the agent program retain files in the C:\temp and C:\ directories?
Answer: Some deployment scripts like resumeScript or reboot or restore take effect based on information retained in these directories. These scripts require information from those files to function as designed. Each script, the level at which it is defined, the script download location, the user running the script, and the location from which the script is run in provided in detail in the Deployment Lifecycle Scripts > Lifecycle Action Script Definition section for both Linux and Windows environments.
Question: Does the worker installer for Windows install any open source tools on Windows workers?
Answer: No, the Window worker installer does not install any open source tools on Windows. It does, however, install ccc_unarchiver, a proprietary tool to open TAR files.
Question: How are application services different from the services created by the agent installation process?
Answer: The agent services and application services are independent of each other.
Agent Services: Specific to the agent installer. When you install the agent, the Agent installer installs some services to help with the installation and maintenance of the management agent. These files include the CliQr Installer Service, Agent Service, and other services mentioned in Question 4 in this section.
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