Merge pull request #2379 from balena-os/support-jetson-power-fan-configs

Support jetson power fan configs

src/config/backends/backend.ts

@@ -41,6 +41,12 @@ export abstract class ConfigBackend {
 	// Example an empty string should return null.
 	public abstract createConfigVarName(configName: string): string | null;
 
+	// Is a reboot required for the given config options?
+	// eslint-disable-next-line @typescript-eslint/no-unused-vars
+	public async isRebootRequired(_opts: ConfigOptions): Promise<boolean> {
+		return true;
+	}
+
 	// Allow a chosen config backend to be initialised
 	public async initialise(): Promise<ConfigBackend> {
 		return this;

src/config/backends/config-txt.ts

@@ -70,14 +70,15 @@ function isBaseParam(dtparam: string): boolean {
  * 	- {BALENA|RESIN}_HOST_CONFIG_gpio = value | "value" | "value1","value2"
  */
 export class ConfigTxt extends ConfigBackend {
-	private static bootConfigVarPrefix = `${constants.hostConfigVarPrefix}CONFIG_`;
-	private static bootConfigPath = hostUtils.pathOnBoot('config.txt');
-
-	public static bootConfigVarRegex = new RegExp(
-		'(?:' + _.escapeRegExp(ConfigTxt.bootConfigVarPrefix) + ')(.+)',
+	private static PREFIX = `${constants.hostConfigVarPrefix}CONFIG_`;
+	private static PATH = hostUtils.pathOnBoot('config.txt');
+	private static REGEX = new RegExp(
+		'(?:' + _.escapeRegExp(ConfigTxt.PREFIX) + ')(.+)',
 	);
-
-	private static forbiddenConfigKeys = [
+	// These keys are not config.txt keys and are managed by the power-fan backend.
+	private static UNSUPPORTED_KEYS = ['power_mode', 'fan_profile'];
+	// These keys are config.txt keys, but are not mutable by the Supervisor.
+	private static FORBIDDEN_KEYS = [
 		'disable_commandline_tags',
 		'cmdline',
 		'kernel',
@@ -89,7 +90,7 @@ export class ConfigTxt extends ConfigBackend {
 		'device_tree_address',
 		'init_emmc_clock',
 		'avoid_safe_mode',
-	];
+	].concat(ConfigTxt.UNSUPPORTED_KEYS);
 
 	public async matches(deviceType: string): Promise<boolean> {
 		return (
@@ -109,11 +110,8 @@ export class ConfigTxt extends ConfigBackend {
 	public async getBootConfig(): Promise<ConfigOptions> {
 		let configContents = '';
 
-		if (await exists(ConfigTxt.bootConfigPath)) {
-			configContents = await hostUtils.readFromBoot(
-				ConfigTxt.bootConfigPath,
-				'utf-8',
-			);
+		if (await exists(ConfigTxt.PATH)) {
+			configContents = await hostUtils.readFromBoot(ConfigTxt.PATH, 'utf-8');
 		} else {
 			return {};
 		}
@@ -227,19 +225,29 @@ export class ConfigTxt extends ConfigBackend {
 		}
 
 		const confStr = `${confStatements.join('\n')}\n`;
-		await hostUtils.writeToBoot(ConfigTxt.bootConfigPath, confStr);
+		await hostUtils.writeToBoot(ConfigTxt.PATH, confStr);
+	}
+
+	public static stripPrefix(name: string): string {
+		if (!name.startsWith(ConfigTxt.PREFIX)) {
+			return name;
+		}
+		return name.substring(ConfigTxt.PREFIX.length);
 	}
 
 	public isSupportedConfig(configName: string): boolean {
-		return !ConfigTxt.forbiddenConfigKeys.includes(configName);
+		return !ConfigTxt.FORBIDDEN_KEYS.includes(configName);
 	}
 
 	public isBootConfigVar(envVar: string): boolean {
-		return envVar.startsWith(ConfigTxt.bootConfigVarPrefix);
+		return (
+			envVar.startsWith(ConfigTxt.PREFIX) &&
+			!ConfigTxt.UNSUPPORTED_KEYS.includes(ConfigTxt.stripPrefix(envVar))
+		);
 	}
 
 	public processConfigVarName(envVar: string): string {
-		return envVar.replace(ConfigTxt.bootConfigVarRegex, '$1');
+		return envVar.replace(ConfigTxt.REGEX, '$1');
 	}
 
 	public processConfigVarValue(key: string, value: string): string | string[] {
@@ -254,7 +262,7 @@ export class ConfigTxt extends ConfigBackend {
 	}
 
 	public createConfigVarName(configName: string): string {
-		return ConfigTxt.bootConfigVarPrefix + configName;
+		return ConfigTxt.PREFIX + configName;
 	}
 
 	// Ensure that the balena-fin overlay is defined in the target configuration

src/config/backends/index.ts

@@ -4,6 +4,8 @@ import { ConfigTxt } from './config-txt';
 import { ConfigFs } from './config-fs';
 import { Odmdata } from './odmdata';
 import { SplashImage } from './splash-image';
+import { PowerFanConfig } from './power-fan';
+import { configJsonBackend } from '..';
 
 export const allBackends = [
 	new Extlinux(),
@@ -12,6 +14,7 @@ export const allBackends = [
 	new ConfigFs(),
 	new Odmdata(),
 	new SplashImage(),
+	new PowerFanConfig(configJsonBackend),
 ];
 
 export function matchesAnyBootConfig(envVar: string): boolean {

src/config/backends/power-fan.ts

@@ -0,0 +1,170 @@
+import { isRight } from 'fp-ts/lib/Either';
+import Reporter from 'io-ts-reporters';
+import * as t from 'io-ts';
+import * as _ from 'lodash';
+
+import { ConfigBackend } from './backend';
+import type { ConfigOptions } from './backend';
+import { schemaTypes } from '../schema-type';
+import log from '../../lib/supervisor-console';
+import * as constants from '../../lib/constants';
+
+type ConfigJsonBackend = {
+	get: (key: 'os') => Promise<unknown>;
+	set: (opts: { os: Record<string, any> }) => Promise<void>;
+};
+
+/**
+ * A backend to handle Jetson power and fan control
+ *
+ * Supports:
+ * 	- {BALENA|RESIN}_HOST_CONFIG_power_mode = "low" | "mid" | "high" | "default" |"$MODE_ID"
+ * 	- {BALENA|RESIN}_HOST_CONFIG_fan_profile = "quiet" | "cool" | "default" |"$MODE_ID"
+ */
+export class PowerFanConfig extends ConfigBackend {
+	private static readonly CONFIGS = new Set(['power_mode', 'fan_profile']);
+	private static readonly PREFIX = `${constants.hostConfigVarPrefix}CONFIG_`;
+	private static readonly SCHEMA = t.exact(
+		t.partial({
+			power: t.exact(
+				t.partial({
+					mode: t.string,
+				}),
+			),
+			fan: t.exact(
+				t.partial({
+					profile: t.string,
+				}),
+			),
+		}),
+	);
+
+	private readonly configJson: ConfigJsonBackend;
+	public constructor(configJson: ConfigJsonBackend) {
+		super();
+		this.configJson = configJson;
+	}
+
+	public static stripPrefix(name: string): string {
+		if (!name.startsWith(PowerFanConfig.PREFIX)) {
+			return name;
+		}
+		return name.substring(PowerFanConfig.PREFIX.length);
+	}
+
+	public async matches(deviceType: string): Promise<boolean> {
+		// We only support Jetpack 6 devices for now, which includes all Orin devices
+		// except for jetson-orin-nx-xv3 which is still on Jetpack 5 as of OS v5.1.36
+		return new Set([
+			'jetson-agx-orin-devkit',
+			'jetson-agx-orin-devkit-64gb',
+			'jetson-orin-nano-devkit-nvme',
+			'jetson-orin-nano-seeed-j3010',
+			'jetson-orin-nx-seeed-j4012',
+			'jetson-orin-nx-xavier-nx-devkit',
+		]).has(deviceType);
+	}
+
+	public async getBootConfig(): Promise<ConfigOptions> {
+		// Get raw config.json contents
+		let rawConf: unknown;
+		try {
+			rawConf = await this.configJson.get('os');
+		} catch (e: unknown) {
+			log.error(
+				`Failed to read config.json while getting power / fan configs: ${(e as Error).message ?? e}`,
+			);
+			return {};
+		}
+
+		// Decode to power fan schema from object type, filtering out unrelated values
+		const powerFanConfig = PowerFanConfig.SCHEMA.decode(rawConf);
+
+		if (isRight(powerFanConfig)) {
+			const conf = powerFanConfig.right;
+			return {
+				...(conf.power?.mode != null && {
+					power_mode: conf.power.mode,
+				}),
+				...(conf.fan?.profile != null && {
+					fan_profile: conf.fan.profile,
+				}),
+			};
+		} else {
+			return {};
+		}
+	}
+
+	public async setBootConfig(opts: ConfigOptions): Promise<void> {
+		// Read raw configs for "os" key from config.json
+		let rawConf;
+		try {
+			rawConf = await this.configJson.get('os');
+		} catch (err: unknown) {
+			log.error(`${(err as Error).message ?? err}`);
+			return;
+		}
+
+		// Decode to "os" object type while leaving in unrelated values
+		const maybeCurrentConf = schemaTypes.os.type.decode(rawConf);
+		if (!isRight(maybeCurrentConf)) {
+			log.error(
+				'Failed to decode current os config:',
+				Reporter.report(maybeCurrentConf),
+			);
+			return;
+		}
+		// Current config could be undefined if there's no os key in config.json, so default to empty object
+		const conf = maybeCurrentConf.right ?? {};
+
+		// Update or delete power mode
+		if ('power_mode' in opts) {
+			conf.power = {
+				mode: opts.power_mode,
+			};
+		} else {
+			delete conf?.power;
+		}
+
+		// Update or delete fan profile
+		if ('fan_profile' in opts) {
+			conf.fan = {
+				profile: opts.fan_profile,
+			};
+		} else {
+			delete conf?.fan;
+		}
+
+		await this.configJson.set({ os: conf });
+	}
+
+	public isSupportedConfig = (name: string): boolean => {
+		return PowerFanConfig.CONFIGS.has(PowerFanConfig.stripPrefix(name));
+	};
+
+	public isBootConfigVar(envVar: string): boolean {
+		return PowerFanConfig.CONFIGS.has(PowerFanConfig.stripPrefix(envVar));
+	}
+
+	public async isRebootRequired(opts: ConfigOptions): Promise<boolean> {
+		const supportedOpts = _.pickBy(
+			_.mapKeys(opts, (_value, key) => PowerFanConfig.stripPrefix(key)),
+			(_value, key) => this.isSupportedConfig(key),
+		);
+		const current = await this.getBootConfig();
+		// A reboot is only required if the power mode is changing
+		return current.power_mode !== supportedOpts.power_mode;
+	}
+
+	public processConfigVarName(envVar: string): string {
+		return PowerFanConfig.stripPrefix(envVar).toLowerCase();
+	}
+
+	public processConfigVarValue(_key: string, value: string): string {
+		return value;
+	}
+
+	public createConfigVarName(name: string): string | null {
+		return `${PowerFanConfig.PREFIX}${name}`;
+	}
+}

src/config/configJson.ts

@@ -3,7 +3,6 @@ import _ from 'lodash';
 
 import * as constants from '../lib/constants';
 import * as hostUtils from '../lib/host-utils';
-import * as osRelease from '../lib/os-release';
 import { takeGlobalLockRO, takeGlobalLockRW } from '../lib/process-lock';
 import type * as Schema from './schema';
 
@@ -12,17 +11,20 @@ export default class ConfigJsonConfigBackend {
 	private readonly writeLockConfigJson: () => Bluebird.Disposer<() => void>;
 
 	private readonly schema: Schema.Schema;
+	/**
+	 * @deprecated configPath is only set by legacy tests
+	 */
 	private readonly configPath?: string;
 
 	private cache: { [key: string]: unknown } = {};
 
-	private readonly init = _.once(async () =>
-		Object.assign(this.cache, await this.read()),
-	);
+	private readonly init = _.once(async () => {
+		Object.assign(this.cache, await this.read());
+	});
 
 	public constructor(schema: Schema.Schema, configPath?: string) {
-		this.configPath = configPath;
 		this.schema = schema;
+		this.configPath = configPath;
 
 		this.writeLockConfigJson = () =>
 			takeGlobalLockRW('config.json').disposer((release) => release());
@@ -37,14 +39,10 @@ export default class ConfigJsonConfigBackend {
 		await Bluebird.using(this.writeLockConfigJson(), async () => {
 			let changed = false;
 			_.forOwn(keyVals, (value, key: T) => {
-				if (this.cache[key] !== value) {
+				if (this.schema[key] != null && !_.isEqual(this.cache[key], value)) {
 					this.cache[key] = value;
 
-					if (
-						value == null &&
-						this.schema[key] != null &&
-						this.schema[key].removeIfNull
-					) {
+					if (value == null && this.schema[key].removeIfNull) {
 						delete this.cache[key];
 					}
 
@@ -57,15 +55,14 @@ export default class ConfigJsonConfigBackend {
 		});
 	}
 
-	public async get(key: string): Promise<unknown> {
+	public async get(key: Schema.SchemaKey): Promise<unknown> {
 		await this.init();
-		return Bluebird.using(
-			this.readLockConfigJson(),
-			async () => this.cache[key],
+		return Bluebird.using(this.readLockConfigJson(), async () =>
+			structuredClone(this.cache[key]),
 		);
 	}
 
-	public async remove(key: string) {
+	public async remove(key: Schema.SchemaKey) {
 		await this.init();
 		return Bluebird.using(this.writeLockConfigJson(), async () => {
 			let changed = false;
@@ -91,6 +88,12 @@ export default class ConfigJsonConfigBackend {
 		return JSON.parse(await hostUtils.readFromBoot(filename, 'utf-8'));
 	}
 
+	/**
+	 * @deprecated Either read the config.json path from lib/constants, or
+	 * pass a validated path to the constructor and fail if no path is passed.
+	 * TODO: Remove this once api-binder tests are migrated. The only
+	 * time configPath is passed to the constructor is in the legacy tests.
+	 */
 	private async path(): Promise<string> {
 		// TODO: Remove this once api-binder tests are migrated. The only
 		// time configPath is passed to the constructor is in the legacy tests.
@@ -98,11 +101,6 @@ export default class ConfigJsonConfigBackend {
 			return this.configPath;
 		}
 
-		const osVersion = await osRelease.getOSVersion(constants.hostOSVersionPath);
-		if (osVersion == null) {
-			throw new Error('Failed to detect OS version!');
-		}
-
 		// The default path in the boot partition
 		return constants.configJsonPath;
 	}

src/config/schema-type.ts

@@ -84,6 +84,10 @@ export const schemaTypes = {
 		type: t.string,
 		default: NullOrUndefined,
 	},
+	os: {
+		type: t.union([t.record(t.string, t.any), t.undefined]),
+		default: NullOrUndefined,
+	},
 
 	// Database types
 	name: {

src/config/schema.ts

@@ -84,6 +84,11 @@ export const schema = {
 		mutable: false,
 		removeIfNull: false,
 	},
+	os: {
+		source: 'config.json',
+		mutable: true,
+		removeIfNull: false,
+	},
 
 	name: {
 		source: 'db',

src/device-config.ts

@@ -529,18 +529,21 @@ async function getBackendSteps(
 	const { deviceType } = await config.getMany(['deviceType']);
 
 	// Check for required bootConfig changes
+	let rebootRequired = false;
 	for (const backend of backends) {
 		if (changeRequired(backend, current, target, deviceType)) {
 			steps.push({
 				action: 'setBootConfig',
 				target,
 			});
+			rebootRequired =
+				(await backend.isRebootRequired(target)) || rebootRequired;
 		}
 	}
 
 	return [
-		// All backend steps require a reboot
-		...(steps.length > 0
+		// All backend steps require a reboot except fan control
+		...(steps.length > 0 && rebootRequired
 			? [{ action: 'setRebootBreadcrumb' } as ConfigStep]
 			: []),
 		...steps,

test/integration/config/configJson.spec.ts

@@ -0,0 +1,203 @@
+import { expect } from 'chai';
+import type { TestFs } from 'mocha-pod';
+import { testfs } from 'mocha-pod';
+import { promises as fs } from 'fs';
+
+import ConfigJsonConfigBackend from '~/src/config/configJson';
+import { schema } from '~/src/config/schema';
+
+describe('ConfigJsonConfigBackend', () => {
+	const CONFIG_PATH = '/mnt/boot/config.json';
+	const os = {
+		power: {
+			mode: 'high',
+		},
+		fan: {
+			profile: 'cool',
+		},
+		network: {
+			connectivity: {
+				uri: 'https://api.balena-cloud.com/connectivity-check',
+				interval: '300',
+				response: 'optional value in the response',
+			},
+			wifi: {
+				randomMacAddressScan: false,
+			},
+		},
+		udevRules: {
+			'56': 'ENV{ID_FS_LABEL_ENC}=="resin-root*", IMPORT{program}="resin_update_state_probe $devnode", SYMLINK+="disk/by-state/$env{RESIN_UPDATE_STATE}"',
+			'64': 'ACTION!="add|change", GOTO="modeswitch_rules_end"\nKERNEL=="ttyACM*", ATTRS{idVendor}=="1546", ATTRS{idProduct}=="1146", TAG+="systemd", ENV{SYSTEMD_WANTS}="u-blox-switch@\'%E{DEVNAME}\'.service"\nLBEL="modeswitch_rules_end"\n',
+		},
+		sshKeys: [
+			'ssh-rsa AAAAB3Nza...M2JB balena@macbook-pro',
+			'ssh-rsa AAAAB3Nza...nFTQ balena@zenbook',
+		],
+	};
+	let configJsonConfigBackend: ConfigJsonConfigBackend;
+	let tfs: TestFs.Enabled;
+
+	beforeEach(() => {
+		configJsonConfigBackend = new ConfigJsonConfigBackend(schema);
+	});
+
+	afterEach(async () => {
+		await tfs.restore();
+	});
+
+	it('should get primitive values for config.json key', async () => {
+		tfs = await testfs({
+			[CONFIG_PATH]: JSON.stringify({
+				apiEndpoint: 'foo',
+				deviceId: 123,
+				persistentLogging: true,
+			}),
+			'/mnt/root/etc/os-release': testfs.from('test/data/etc/os-release'),
+		}).enable();
+
+		expect(await configJsonConfigBackend.get('apiEndpoint')).to.equal('foo');
+		expect(await configJsonConfigBackend.get('deviceId')).to.equal(123);
+		expect(await configJsonConfigBackend.get('persistentLogging')).to.equal(
+			true,
+		);
+	});
+
+	it('should get object values for config.json "os" key', async () => {
+		tfs = await testfs({
+			[CONFIG_PATH]: JSON.stringify({
+				os,
+			}),
+			'/mnt/root/etc/os-release': testfs.from('test/data/etc/os-release'),
+		}).enable();
+
+		expect(await configJsonConfigBackend.get('os')).to.deep.equal(os);
+	});
+
+	it('should get object values for config.json "os" key while "os" is empty', async () => {
+		tfs = await testfs({
+			[CONFIG_PATH]: JSON.stringify({}),
+			'/mnt/root/etc/os-release': testfs.from('test/data/etc/os-release'),
+		}).enable();
+
+		expect(await configJsonConfigBackend.get('os')).to.be.undefined;
+	});
+
+	it('should set primitive values for config.json key', async () => {
+		tfs = await testfs({
+			[CONFIG_PATH]: JSON.stringify({
+				apiEndpoint: 'foo',
+				deviceId: 123,
+				persistentLogging: true,
+			}),
+			'/mnt/root/etc/os-release': testfs.from('test/data/etc/os-release'),
+		}).enable();
+
+		await configJsonConfigBackend.set({
+			apiEndpoint: 'bar',
+			deviceId: 456,
+			persistentLogging: false,
+		});
+
+		expect(await configJsonConfigBackend.get('apiEndpoint')).to.equal('bar');
+		expect(await configJsonConfigBackend.get('deviceId')).to.equal(456);
+		expect(await configJsonConfigBackend.get('persistentLogging')).to.equal(
+			false,
+		);
+	});
+
+	it('should set object values for config.json "os" key', async () => {
+		tfs = await testfs({
+			[CONFIG_PATH]: JSON.stringify({
+				os,
+			}),
+			'/mnt/root/etc/os-release': testfs.from('test/data/etc/os-release'),
+		}).enable();
+
+		const newOs = {
+			power: {
+				mode: 'low',
+			},
+			network: {
+				wifi: {
+					randomMacAddressScan: true,
+				},
+			},
+			udevRules: {
+				'56': 'ENV{ID_FS_LABEL_ENC}=="resin-root*", IMPORT{program}="resin_update_state_probe $devnode", SYMLINK+="disk/by-state/$env{RESIN_UPDATE_STATE}"',
+			},
+			sshKeys: ['ssh-rsa AAAAB3Nza...M2JB balena@macbook-pro'],
+		};
+
+		await configJsonConfigBackend.set({
+			os: newOs,
+		});
+
+		expect(await configJsonConfigBackend.get('os')).to.deep.equal(newOs);
+	});
+
+	it('should set object values for config.json "os" key while "os" is empty', async () => {
+		tfs = await testfs({
+			[CONFIG_PATH]: JSON.stringify({}),
+			'/mnt/root/etc/os-release': testfs.from('test/data/etc/os-release'),
+		}).enable();
+
+		await configJsonConfigBackend.set({
+			os,
+		});
+
+		expect(await configJsonConfigBackend.get('os')).to.deep.equal(os);
+	});
+
+	// The following test cases may be unnecessary as they test cases where another party
+	// writes to config.json directly (instead of through setting config vars on the API).
+	it('should get cached value even if actual value has changed', async () => {
+		tfs = await testfs({
+			[CONFIG_PATH]: JSON.stringify({
+				apiEndpoint: 'foo',
+			}),
+			'/mnt/root/etc/os-release': testfs.from('test/data/etc/os-release'),
+		}).enable();
+
+		// The cached value should be returned
+		expect(await configJsonConfigBackend.get('apiEndpoint')).to.equal('foo');
+
+		// Change the value in the file
+		await fs.writeFile(
+			CONFIG_PATH,
+			JSON.stringify({
+				apiEndpoint: 'bar',
+			}),
+		);
+
+		// Unintended behavior: the cached value should not be overwritten
+		expect(await configJsonConfigBackend.get('apiEndpoint')).to.equal('foo');
+	});
+
+	it('should set value and refresh cache to equal new value', async () => {
+		tfs = await testfs({
+			[CONFIG_PATH]: JSON.stringify({
+				apiEndpoint: 'foo',
+			}),
+			'/mnt/root/etc/os-release': testfs.from('test/data/etc/os-release'),
+		}).enable();
+
+		expect(await configJsonConfigBackend.get('apiEndpoint')).to.equal('foo');
+
+		await fs.writeFile(
+			CONFIG_PATH,
+			JSON.stringify({
+				apiEndpoint: 'bar',
+			}),
+		);
+
+		// Unintended behavior: cached value should not have been updated
+		// as the change was not written to config.json by the Supervisor
+		expect(await configJsonConfigBackend.get('apiEndpoint')).to.equal('foo');
+
+		await configJsonConfigBackend.set({
+			apiEndpoint: 'baz',
+		});
+
+		expect(await configJsonConfigBackend.get('apiEndpoint')).to.equal('baz');
+	});
+});

test/integration/config/power-fan.spec.ts

@@ -0,0 +1,577 @@
+import { expect } from 'chai';
+import { stripIndent } from 'common-tags';
+import { testfs } from 'mocha-pod';
+import type { SinonStub } from 'sinon';
+
+import { PowerFanConfig } from '~/src/config/backends/power-fan';
+import { Extlinux } from '~/src/config/backends/extlinux';
+import { ExtraUEnv } from '~/src/config/backends/extra-uEnv';
+import { ConfigTxt } from '~/src/config/backends/config-txt';
+import { ConfigFs } from '~/src/config/backends/config-fs';
+import { Odmdata } from '~/src/config/backends/odmdata';
+import { SplashImage } from '~/src/config/backends/splash-image';
+import ConfigJsonConfigBackend from '~/src/config/configJson';
+import { schema } from '~/src/config/schema';
+import * as hostUtils from '~/lib/host-utils';
+import log from '~/lib/supervisor-console';
+
+const SUPPORTED_DEVICE_TYPES = [
+	'jetson-agx-orin-devkit',
+	'jetson-agx-orin-devkit-64gb',
+	'jetson-orin-nano-devkit-nvme',
+	'jetson-orin-nano-seeed-j3010',
+	'jetson-orin-nx-seeed-j4012',
+	'jetson-orin-nx-xavier-nx-devkit',
+];
+
+const UNSUPPORTED_DEVICE_TYPES = ['jetson-orin-nx-xv3'];
+
+describe('config/power-fan', () => {
+	const CONFIG_PATH = hostUtils.pathOnBoot('config.json');
+	const generateConfigJsonBackend = () => new ConfigJsonConfigBackend(schema);
+	let powerFanConf: PowerFanConfig;
+
+	beforeEach(async () => {
+		await testfs({
+			'/mnt/root/etc/os-release': testfs.from('test/data/etc/os-release'),
+		}).enable();
+	});
+
+	afterEach(async () => {
+		await testfs.restore();
+	});
+
+	it('only matches supported devices', async () => {
+		powerFanConf = new PowerFanConfig(generateConfigJsonBackend());
+		for (const deviceType of SUPPORTED_DEVICE_TYPES) {
+			expect(await powerFanConf.matches(deviceType)).to.be.true;
+		}
+
+		for (const deviceType of UNSUPPORTED_DEVICE_TYPES) {
+			expect(await powerFanConf.matches(deviceType)).to.be.false;
+		}
+	});
+
+	it('correctly gets boot configs from config.json', async () => {
+		const getConfigJson = (powerMode: string, fanProfile: string) => {
+			return stripIndent`
+			{
+				"os": {
+					"extra": "field",
+					"power": {
+						"mode": "${powerMode}"
+					},
+					"fan": {
+						"profile": "${fanProfile}"
+					}
+				}
+			}`;
+		};
+
+		for (const powerMode of ['low', 'mid', 'high', 'custom_power']) {
+			for (const fanProfile of ['quiet', 'default', 'cool', 'custom_fan']) {
+				await testfs({
+					[CONFIG_PATH]: getConfigJson(powerMode, fanProfile),
+				}).enable();
+
+				// ConfigJsonConfigBackend uses a cache, so setting a Supervisor-managed value
+				// directly in config.json (thus circumventing ConfigJsonConfigBackend)
+				// will not be reflected in the ConfigJsonConfigBackend instance.
+				// We need to create a new instance which will recreate the cache
+				// in order to get the latest value.
+				powerFanConf = new PowerFanConfig(generateConfigJsonBackend());
+
+				expect(await powerFanConf.getBootConfig()).to.deep.equal({
+					power_mode: powerMode,
+					fan_profile: fanProfile,
+				});
+
+				await testfs.restore();
+			}
+		}
+	});
+
+	it('correctly gets boot configs if power mode is not set', async () => {
+		await testfs({
+			[CONFIG_PATH]: stripIndent`
+            {   
+                "os": {
+					"extra": "field",
+                    "fan": {
+                        "profile": "quiet"
+                    }
+                }
+            }`,
+		}).enable();
+		powerFanConf = new PowerFanConfig(generateConfigJsonBackend());
+
+		const config = await powerFanConf.getBootConfig();
+		expect(config).to.deep.equal({
+			fan_profile: 'quiet',
+		});
+	});
+
+	it('correctly gets boot configs if fan profile is not set', async () => {
+		await testfs({
+			[CONFIG_PATH]: stripIndent`
+            {   
+                "os": {
+					"extra": "field",
+                    "power": {
+                        "mode": "low"
+                    }
+                }
+            }`,
+		}).enable();
+		powerFanConf = new PowerFanConfig(generateConfigJsonBackend());
+
+		const config = await powerFanConf.getBootConfig();
+		expect(config).to.deep.equal({
+			power_mode: 'low',
+		});
+	});
+
+	it('correctly gets boot configs if no relevant boot configs are set', async () => {
+		await testfs({
+			[CONFIG_PATH]: stripIndent`
+            {   
+                "os": {
+					"extra": "field"
+				}
+            }`,
+		}).enable();
+		powerFanConf = new PowerFanConfig(generateConfigJsonBackend());
+
+		const config = await powerFanConf.getBootConfig();
+		expect(config).to.deep.equal({});
+	});
+
+	it('ignores unrelated fields in config.json when getting boot configs', async () => {
+		const configStr = stripIndent`
+		{   
+			"apiEndpoint": "https://api.balena-cloud.com",
+			"uuid": "deadbeef",
+			"os": {
+				"power": {
+					"mode": "low",
+					"extra": "field"
+				},
+				"extra2": "field2",
+				"fan": {
+					"profile": "quiet",
+					"extra3": "field3"
+				},
+				"network": {
+					"connectivity": {
+						"uri": "https://api.balena-cloud.com/connectivity-check",
+						"interval": "300",
+						"response": "optional value in the response"
+					},
+					"wifi": {
+						"randomMacAddressScan": false
+					}
+				}
+			}
+		}`;
+		await testfs({
+			[CONFIG_PATH]: configStr,
+		}).enable();
+		powerFanConf = new PowerFanConfig(generateConfigJsonBackend());
+
+		const config = await powerFanConf.getBootConfig();
+		expect(config).to.deep.equal({
+			power_mode: 'low',
+			fan_profile: 'quiet',
+		});
+
+		// Check that unrelated fields are unchanged
+		const configJson = await hostUtils.readFromBoot(CONFIG_PATH, 'utf-8');
+		expect(configJson).to.equal(configStr);
+	});
+
+	it('gets boot configs in config.json while current config is empty', async () => {
+		await testfs({
+			[CONFIG_PATH]: '{}',
+		}).enable();
+		powerFanConf = new PowerFanConfig(generateConfigJsonBackend());
+
+		expect(await powerFanConf.getBootConfig()).to.deep.equal({});
+	});
+
+	it('sets boot configs in config.json', async () => {
+		await testfs({
+			[CONFIG_PATH]: stripIndent`
+			{
+				"os": {
+					"extra": "field"
+				}
+			}`,
+		}).enable();
+		powerFanConf = new PowerFanConfig(generateConfigJsonBackend());
+
+		expect(await powerFanConf.getBootConfig()).to.deep.equal({});
+
+		await powerFanConf.setBootConfig({
+			power_mode: 'low',
+			fan_profile: 'quiet',
+		});
+
+		expect(await powerFanConf.getBootConfig()).to.deep.equal({
+			power_mode: 'low',
+			fan_profile: 'quiet',
+		});
+
+		// Sanity check that config.json is updated
+		const configJson = await hostUtils.readFromBoot(CONFIG_PATH, 'utf-8');
+		expect(configJson).to.deep.equal(
+			JSON.stringify({
+				os: {
+					extra: 'field',
+					power: {
+						mode: 'low',
+					},
+					fan: {
+						profile: 'quiet',
+					},
+				},
+			}),
+		);
+	});
+
+	it('sets boot configs in config.json while removing any unspecified boot configs', async () => {
+		await testfs({
+			[CONFIG_PATH]: stripIndent`
+			{
+				"os": {
+					"extra": "field",
+					"power": {
+						"mode": "low"
+					}
+				}
+			}`,
+		}).enable();
+		powerFanConf = new PowerFanConfig(generateConfigJsonBackend());
+
+		await powerFanConf.setBootConfig({
+			fan_profile: 'cool',
+		});
+
+		const config = await powerFanConf.getBootConfig();
+		expect(config).to.deep.equal({
+			fan_profile: 'cool',
+		});
+
+		// Sanity check that power mode is removed
+		const configJson = await hostUtils.readFromBoot(CONFIG_PATH, 'utf-8');
+		expect(configJson).to.deep.equal(
+			JSON.stringify({
+				os: {
+					extra: 'field',
+					fan: {
+						profile: 'cool',
+					},
+				},
+			}),
+		);
+	});
+
+	it('sets boot configs in config.json while current config is empty', async () => {
+		await testfs({
+			[CONFIG_PATH]: '{}',
+		}).enable();
+		powerFanConf = new PowerFanConfig(generateConfigJsonBackend());
+
+		await powerFanConf.setBootConfig({
+			power_mode: 'low',
+			fan_profile: 'quiet',
+		});
+
+		expect(await powerFanConf.getBootConfig()).to.deep.equal({
+			power_mode: 'low',
+			fan_profile: 'quiet',
+		});
+
+		// Sanity check that config.json is updated
+		const configJson = await hostUtils.readFromBoot(CONFIG_PATH, 'utf-8');
+		expect(configJson).to.deep.equal(
+			JSON.stringify({
+				os: {
+					power: {
+						mode: 'low',
+					},
+					fan: {
+						profile: 'quiet',
+					},
+				},
+			}),
+		);
+	});
+
+	it('sets boot configs in config.json while current and target config are empty', async () => {
+		await testfs({
+			[CONFIG_PATH]: '{}',
+		}).enable();
+		powerFanConf = new PowerFanConfig(generateConfigJsonBackend());
+
+		await powerFanConf.setBootConfig({});
+
+		expect(await powerFanConf.getBootConfig()).to.deep.equal({});
+
+		// Sanity check that config.json is empty
+		const configJson = await hostUtils.readFromBoot(CONFIG_PATH, 'utf-8');
+		expect(configJson).to.deep.equal(JSON.stringify({ os: {} }));
+	});
+
+	it('handles setting configs correctly when target configs are empty string', async () => {
+		await testfs({
+			[CONFIG_PATH]: stripIndent`
+			{
+				"os": {
+					"extra": "field",
+					"power": {
+						"mode": "low"
+					}
+				}
+			}`,
+		}).enable();
+		powerFanConf = new PowerFanConfig(generateConfigJsonBackend());
+
+		await powerFanConf.setBootConfig({
+			fan_profile: '',
+		});
+
+		const config = await powerFanConf.getBootConfig();
+		expect(config).to.deep.equal({
+			fan_profile: '',
+		});
+
+		// Sanity check that config.json is updated
+		const configJson = await hostUtils.readFromBoot(CONFIG_PATH, 'utf-8');
+		expect(configJson).to.deep.equal(
+			JSON.stringify({
+				os: {
+					extra: 'field',
+					fan: {
+						profile: '',
+					},
+				},
+			}),
+		);
+	});
+
+	it('does not touch fields besides os.power and os.fan in config.json when setting boot configs', async () => {
+		await testfs({
+			// Note that extra fields in os.power and os.fan are removed when setting, as os.power
+			// and os.fan are considered managed by the Supervisor.
+			[CONFIG_PATH]: stripIndent`
+			{   
+				"apiEndpoint": "https://api.balena-cloud.com",
+				"uuid": "deadbeef",
+				"os": {
+					"power": {
+						"mode": "low",
+						"extra": "field"
+					},
+					"extra2": "field2",
+					"fan": {
+						"profile": "quiet",
+						"extra3": "field3"
+					},
+					"network": {
+						"connectivity": {
+							"uri": "https://api.balena-cloud.com/connectivity-check",
+							"interval": "300",
+							"response": "optional value in the response"
+						},
+						"wifi": {
+							"randomMacAddressScan": false
+						}
+					}
+				}
+			}`,
+		}).enable();
+		powerFanConf = new PowerFanConfig(generateConfigJsonBackend());
+
+		await powerFanConf.setBootConfig({
+			power_mode: 'high',
+			fan_profile: 'cool',
+		});
+
+		expect(await powerFanConf.getBootConfig()).to.deep.equal({
+			power_mode: 'high',
+			fan_profile: 'cool',
+		});
+
+		// Sanity check that os.power and os.fan are updated
+		const configJson = await hostUtils.readFromBoot(CONFIG_PATH, 'utf-8');
+		expect(configJson).to.deep.equal(
+			JSON.stringify({
+				apiEndpoint: 'https://api.balena-cloud.com',
+				uuid: 'deadbeef',
+				os: {
+					power: {
+						// Extra fields in os.power are removed when setting
+						mode: 'high',
+					},
+					extra2: 'field2',
+					fan: {
+						// Extra fields in os.fan are removed when setting
+						profile: 'cool',
+					},
+					network: {
+						connectivity: {
+							uri: 'https://api.balena-cloud.com/connectivity-check',
+							interval: '300',
+							response: 'optional value in the response',
+						},
+						wifi: {
+							randomMacAddressScan: false,
+						},
+					},
+				},
+			}),
+		);
+	});
+
+	it('does not touch fields besides os.power and os.fan in config.json when removing boot configs', async () => {
+		await testfs({
+			[CONFIG_PATH]: stripIndent`
+			{   
+				"apiEndpoint": "https://api.balena-cloud.com",
+				"uuid": "deadbeef",
+				"os": {
+					"power": {
+						"mode": "low",
+						"extra": "field"
+					},
+					"extra2": "field2",
+					"fan": {
+						"profile": "quiet",
+						"extra3": "field3"
+					},
+					"network": {
+						"connectivity": {
+							"uri": "https://api.balena-cloud.com/connectivity-check",
+							"interval": "300",
+							"response": "optional value in the response"
+						},
+						"wifi": {
+							"randomMacAddressScan": false
+						}
+					}
+				}
+			}`,
+		}).enable();
+		powerFanConf = new PowerFanConfig(generateConfigJsonBackend());
+
+		await powerFanConf.setBootConfig({});
+
+		expect(await powerFanConf.getBootConfig()).to.deep.equal({});
+
+		// Sanity check that os.power and os.fan are removed
+		const configJson = await hostUtils.readFromBoot(CONFIG_PATH, 'utf-8');
+		expect(configJson).to.deep.equal(
+			JSON.stringify({
+				apiEndpoint: 'https://api.balena-cloud.com',
+				uuid: 'deadbeef',
+				os: {
+					extra2: 'field2',
+					network: {
+						connectivity: {
+							uri: 'https://api.balena-cloud.com/connectivity-check',
+							interval: '300',
+							response: 'optional value in the response',
+						},
+						wifi: {
+							randomMacAddressScan: false,
+						},
+					},
+				},
+			}),
+		);
+	});
+
+	it('returns empty object with warning if config.json cannot be parsed', async () => {
+		await testfs({
+			[CONFIG_PATH]: 'not json',
+		}).enable();
+		powerFanConf = new PowerFanConfig(generateConfigJsonBackend());
+
+		(log.error as SinonStub).resetHistory();
+
+		const config = await powerFanConf.getBootConfig();
+		expect(config).to.deep.equal({});
+		expect(log.error as SinonStub).to.have.been.calledWithMatch(
+			'Failed to read config.json while getting power / fan configs:',
+		);
+	});
+
+	it('returns empty object if boot config does not have the right schema', async () => {
+		await testfs({
+			[CONFIG_PATH]: stripIndent`
+            {
+                "os": {
+                    "power": "not an object",
+                    "fan": "also not an object",
+					"extra": "field"
+                }
+            }`,
+		}).enable();
+		powerFanConf = new PowerFanConfig(generateConfigJsonBackend());
+		expect(await powerFanConf.getBootConfig()).to.deep.equal({});
+	});
+
+	it('is the only config backend that supports power mode and fan profile', () => {
+		const otherBackends = [
+			new Extlinux(),
+			new ExtraUEnv(),
+			new ConfigTxt(),
+			new ConfigFs(),
+			new Odmdata(),
+			new SplashImage(),
+		];
+		powerFanConf = new PowerFanConfig(generateConfigJsonBackend());
+
+		for (const config of ['power_mode', 'fan_profile']) {
+			for (const backend of otherBackends) {
+				expect(backend.isBootConfigVar(`HOST_CONFIG_${config}`)).to.be.false;
+				expect(backend.isSupportedConfig(config)).to.be.false;
+			}
+
+			expect(powerFanConf.isBootConfigVar(`HOST_CONFIG_${config}`)).to.be.true;
+			expect(powerFanConf.isSupportedConfig(config)).to.be.true;
+		}
+	});
+
+	it('converts supported config vars to boot configs regardless of case', () => {
+		powerFanConf = new PowerFanConfig(generateConfigJsonBackend());
+		for (const config of ['power_mode', 'fan_profile']) {
+			expect(
+				powerFanConf.processConfigVarName(`HOST_CONFIG_${config}`),
+			).to.equal(config);
+			expect(
+				powerFanConf.processConfigVarName(
+					`HOST_CONFIG_${config.toUpperCase()}`,
+				),
+			).to.equal(config);
+		}
+	});
+
+	it('allows any value for power mode and fan profile', () => {
+		powerFanConf = new PowerFanConfig(generateConfigJsonBackend());
+		for (const config of ['power_mode', 'fan_profile']) {
+			expect(powerFanConf.processConfigVarValue(config, 'any value')).to.equal(
+				'any value',
+			);
+		}
+	});
+
+	it('creates supported config vars from boot configs', () => {
+		powerFanConf = new PowerFanConfig(generateConfigJsonBackend());
+		for (const config of ['power_mode', 'fan_profile']) {
+			expect(powerFanConf.createConfigVarName(config)).to.equal(
+				`HOST_CONFIG_${config}`,
+			);
+		}
+	});
+});

test/integration/config/utils.spec.ts

@@ -7,6 +7,8 @@ import { Extlinux } from '~/src/config/backends/extlinux';
 import { ConfigTxt } from '~/src/config/backends/config-txt';
 import { ConfigFs } from '~/src/config/backends/config-fs';
 import { SplashImage } from '~/src/config/backends/splash-image';
+import { PowerFanConfig } from '~/src/config/backends/power-fan';
+import { configJsonBackend } from '~/src/config';
 import type { ConfigBackend } from '~/src/config/backends/backend';
 
 import * as hostUtils from '~/lib/host-utils';
@@ -63,6 +65,7 @@ const BACKENDS: Record<string, ConfigBackend> = {
 	configtxt: new ConfigTxt(),
 	configfs: new ConfigFs(),
 	splashImage: new SplashImage(),
+	powerFan: new PowerFanConfig(configJsonBackend),
 };
 
 const CONFIGS = {
@@ -123,4 +126,14 @@ const CONFIGS = {
 	// 		ssdt: ['spidev1,1']
 	// 	},
 	// },
+	powerFan: {
+		envVars: {
+			HOST_CONFIG_power_mode: 'low',
+			HOST_CONFIG_fan_profile: 'quiet',
+		},
+		bootConfig: {
+			power_mode: 'low',
+			fan_profile: 'quiet',
+		},
+	},
 };