global-localhost / contracts

Resin.io Base Contracts

Balena Base Contracts

The collection of contracts and partials across the balena system.

Contracts

Each contract is a .json file inside the contracts/ directory. The convention is to store one contract per file, located in contracts/<type>/<slug>.json.

Partials

This directory contains partials that apply to certain combinations of contracts. The convention is to store a partial in partials/<combination>/<combination instantiation>/<partial>.tpl. Here are some examples:

partials/sw.os+arch.sw/debian+amd64/installation.tpl
partials/sw.os+arch.sw/debian/installation.tpl
partials/hw.device-type/ts4900/remove-install-media.tpl

The combination section defines the types of contracts that come into play for a particular partials subtree, separated by a + symbol. If the combination is sw.os+arch.sw, then it means that the subtree will take into account the combination of operating systems and architectures. Note that there can be combinations of a single type.

The combination instantiation section defines a subtree for a specific set of contracts that match the combination type. If the combination is sw.os+arch.sw, a valid combination instantiation can be debian+amd64, which is the subtree that will be selected when matching the Debian GNU/Linux contract with the amd64 architecture contract.

Note that a combination instantiation may use @ symbols to define subtrees for a specific version of one or more contracts in the combination. For example, debian@wheezy+amd64 will be the subtree containing partials for the combination of Debian Wheezy and amd64.

You can also omit trailing portions of the combination instantiation to implement wildcards. If the combination is sw.os+arch.sw and the instantiation is debian, it means that such subtree will apply to the combination of Debian GNU/Linux with any architecture.

The partial tree is then traversed from specific to general, until a match is found. This is the path that the contract system will follow when searching for the download template on the sw.os+arch.sw combination:

sw.os+arch.sw/<os>@<version>+<arch>@<version>/download.tpl
sw.os+arch.sw/<os>@<version>+<arch>/download.tpl
sw.os+arch.sw/<os>+<arch>@<version>/download.tpl
sw.os+arch.sw/<os>+<arch>/download.tpl
sw.os+arch.sw/<os>/download.tpl

Contribute

• Issue Tracker: github.com/balena-io/contracts/issues
• Source Code: github.com/balena-io/contracts

Dependencies

• Node.js

You can perform a set of static analysis checks to find the most common types of errors by running:

npm test

License

The project is licensed under the Apache 2.0 license.