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NervesHub stores firmware as fwup-format .fw files — ZIP-based archives that carry a cryptographic signature alongside the filesystem image. Before a device applies an update, it verifies the signature against a trusted public key registered with NervesHub. This end-to-end signing chain ensures that no untrusted firmware can be installed on your devices, even if your update infrastructure is compromised.
A firmware entry’s UUID is derived from the content of the .fw file. Uploading the same binary twice produces the same UUID, and NervesHub will skip the upload on the second attempt. This makes CI pipelines idempotent — re-running a failed upload job is always safe.

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Build Firmware

Build your Nerves firmware with the standard Mix workflow. Set MIX_TARGET to your hardware target before running mix firmware:
The compiled .fw file is written to ./_build/${MIX_TARGET}_dev/nerves/images/my_project.fw by default. Adjust the path to match your application name and MIX_ENV.

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Create a Signing Key

If you have not yet created a signing key for your product, create one now. The nh key create command generates a signing keypair and registers the public key with NervesHub:
Store the private key material in a secure location (a secrets manager, HSM, or encrypted CI/CD variable). You will need it every time you upload firmware. The public key is stored in NervesHub and distributed to devices automatically.

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Sign Firmware

You can sign a firmware file independently of uploading it — useful when the signing step runs on a separate secure host or HSM, and the resulting signed file is then passed to a build or deployment system:
This writes the signature into the .fw archive in place. The signing key’s private key material must be accessible to the host running this command.

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Upload Firmware

Upload a firmware file to NervesHub. The CLI signs the firmware with your registered key before uploading:
If you manage multiple signing keys, specify which key to use:
A successful upload prints the firmware UUID. Save this UUID if you intend to create a release manually in the next step.

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List and Inspect Firmware

List all firmware binaries uploaded to the current product:
Inspect the metadata for a specific firmware entry by UUID:
The metadata includes the firmware version, platform, architecture, upload timestamp, and the signing key used.

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Download and Delete Firmware

Download a firmware binary to inspect it locally or re-sign it with a different key:
Delete a firmware entry that is no longer needed. You cannot delete firmware that is referenced by an active deployment group:

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CI/CD Pattern

Automate firmware builds and uploads in your CI/CD pipeline using environment variables. The example below builds firmware and uploads it, optionally shipping it to a named deployment group in a single command:
NERVES_HUB_TOKEN is a personal access token or CI token generated in the NervesCloud UI under Account → API Tokens. Store it as a protected secret in your CI/CD system — never commit it to source control. The --deploy flag creates a release against the existing deployment group named "production" with the newly uploaded firmware, combining the upload and rollout steps into one command.