Update the AWS IoT Greengrass Core software (OTA)
The AWS IoT Greengrass Core software comprises the Greengrass nucleus component and other optional components that you can deploy to your devices to perform over-the-air (OTA) updates of the software. This feature is built in to the AWS IoT Greengrass Core software.
OTA updates make it more efficient to:
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Fix security vulnerabilities.
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Address software stability issues.
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Deploy new or improved features.
Topics
Requirements
The following requirements apply to deploy OTA updates of the AWS IoT Greengrass Core software:
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The Greengrass core device must have a connection to the AWS Cloud to receive the deployment.
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The Greengrass core device must be correctly configured and provisioned with certificates and keys for authentication with AWS IoT Core and AWS IoT Greengrass.
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The AWS IoT Greengrass Core software must be set up and running as a system service. OTA updates don't work if you run the nucleus from the JAR file,
Greengrass.jar. For more information, see Configure the Greengrass nucleus as a system service.
Considerations for core devices
Before you perform an OTA update, be aware of the impact on the core devices that you update and their connected client devices:
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The Greengrass nucleus shuts down.
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All components running on the core device also shut down. If those components write to local resources, they might leave those resources in an incorrect state unless shut down properly. Components can use interprocess communication to tell the nucleus component to defer the update until they clean up the resources that they use.
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While the nucleus component is shut down, the core device loses its connections with the AWS Cloud and local devices. The core device won't route messages from client devices while shut down.
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Long-lived Lambda functions that run as components lose their dynamic state information and drop all pending work.
Greengrass nucleus update behavior
When you deploy a component, AWS IoT Greengrass installs the latest supported versions of all of that component's dependencies. Because of this, new patch versions of AWS-provided public components might be automatically deployed to your core devices if you add new devices to a thing group, or you update the deployment that targets those devices. Some automatic updates, such as a nucleus update, can cause your devices to restart unexpectedly.
When the version of the Greengrass nucleus component changes, the AWS IoT Greengrass Core software—which includes the nucleus and all other components on your device—restarts to apply the changes. Because of the impact on core devices when the nucleus component is updated, you might want to control when a new nucleus patch version is deployed to your devices. To do so, you must directly include the Greengrass nucleus component in your deployment. Directly including a component means that you include a specific version of that component in your deployment configuration and do not rely on component dependencies to deploy that component to your devices. For more information about defining dependencies in your component recipes, see Recipe format.
Review the following table to understand the update behavior for the Greengrass nucleus component based on your actions and deployment configurations.
| Action | Deployment configuration | Nucleus update behavior |
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| Add new devices to a thing group targeted by an existing deployment without revising the deployment. | The deployment does not directly include Greengrass nucleus. The deployment directly includes at least one AWS-provided component, or includes a custom component that depends on an AWS-provided component or on the Greengrass nucleus. |
On new devices, installs the latest patch version of nucleus that meets all component dependency requirements. On existing devices, does not update the installed version of the nucleus. |
| Add new devices to a thing group targeted by an existing deployment without revising the deployment. |
The deployment directly includes a specific version of the Greengrass nucleus. |
On new devices, installs the specified nucleus version. On existing devices, does not update the installed version of the nucleus. |
| Create a new deployment or revise an existing deployment. | The deployment does not directly include Greengrass nucleus. The deployment directly includes at least one AWS-provided component, or includes a custom component that depends on an AWS-provided component or on the Greengrass nucleus. |
On all targeted devices, installs the latest patch version of the nucleus that meets all component dependency requirements, including on any new devices that you add to the targeted thing group. |
| Create a new deployment or revise an existing deployment. | The deployment directly includes a specific version of the Greengrass nucleus. | On all targeted devices, installs the specified nucleus version, including any new devices that you add to the targeted thing group. |
Perform an OTA update
To perform an OTA update, create a deployment that includes the nucleus component and the version to install.
