In order to ensure a secure and robust update process, Mender needs additional metadata alongside the raw bits of the update payload. Depending on the version of the Artifact used, the metadata might be different, but must contain the:
To handle the requirements mentioned above, Mender uses a
specific file format, identified by its
.mender suffix which is also known as
a Mender Artifact or simply an Artifact. All relevant components of Mender,
such as the client and server, understand and use only this specific file
format when doing software deployments.
Internally, a Mender Artifact is simply a file archive in the tarball format. It contains several files for incorporating versioning, extensions, metadata and the payload file(s).
Artifact payloads support multiple compression algorithms, and are compressed by default.
The diagram below shows an example of the main attributes and structure of a Mender Artifact file.
The exact Artifact format may vary between versions.
More details about the exact format of the Mender Artifact can be found in the Mender Artifact file documentation.
Mender is constantly evolving to adapt to the needs of its users, and the Mender Artifact format has several revisions. See the Compatibility section for an overview of which versions of the Mender Artifact format are supported by which Mender client versions.
The command-line utility
mender-artifact is the best way to work directly with
Mender Artifacts. It allows you to view, create, modify and sign all types of
Mender Artifacts. Get it in the
Mender also has OS-level integrations for creating system updates as part of your existing OS build process. Learn more in the Creating Artifacts section.
To verify that the Artifact comes from a trusted source, the Mender Artifact format supports end-to-end signing and verification. In order to create a signed Artifact, please follow the instructions at Signing and verifying Mender Artifact.