About the Worker
To deploy VMs and run applications on VMs that use the CloudCenter platform, you need the Management Agent installed on each VM. 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. Once the Management Agent is started, it needs access to the Cisco hosted bundle store () or to your locally-installed custom bundle store to download and start the service.
The Worker image provided or shared by Cisco contains the agent pre-installed using the CentOS 6 operating systems for some supported clouds. These worker images save you time as you do not need to explicitly install the Management Agent yourself. A Worker image becomes fully functional after you deploy the Worker VM to the cloud.
See Options to Install the Worker for details on how you can install the worker.
Management Agent Tasks
The Management 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.
An agent can be used in two modes.
A lightweight Management Agent, called AgentLite, can be installed on VMs that have been imported into CloudCenter.
AgentLite has limited capabilities and can only be used to run custom actions on Imported VMs which were not deployed via the Workload Manager.
AgentLite is an alternate option for VMs that do not require the capability to launch applications but do require some basic CloudCenter functionality like performing platform actions.
If installed, the Virtual Machines page and the VM Details page display the icon and version.
See Virtual Machine Management > AgentLite for additional details.
Deployed by Workload Manager:
Runs on workers created as part of applications deployed by the Workload Manager.
In this mode, it has all available capabilities listed in the About the Worker and Management Agent Tasks sections above.
Question: Is the Management Agent or AgentLite required?
Answer: You do not need to install either the Management Agent or AgentLite in the following cases:
If a service is defined as agentless (without an agent, see Custom Service Definition for additional details), then the applications running these services do not require an agent to be installed.
If you don't run custom scripts on imported VMs, you can continue use these VMs without installing AgentLite.
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: Is the authorized_keys folder automatically deleted?
Answer: Yes. After a VM launch the Workload Manager cleans up the authorized keys specified in the /root/.ssh/authorized_keys file for all OS types (except Ubunu) during the node initialization phase. For Ubuntu OS, the Workload Manager removes the authorized_keys from the /home/ubuntu/.ssh/ folder. After removing the authorized_keys file, the agent injects the specified or auto-generated keys associated with a cliqruser. The cliqruser credentials can be used to log into the VM.
If you do not want the authorized_keys file to be automatically deleted, be sure to set the following flag in the worker image:
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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