device-config: Add migration for SUPERVISOR_DELTA_APPLY_TIMEOUT

The default value for the delta apply timeout was changed from `''` to
`'0'` (note strings as these are database values) - but if the value
existed in the database already, this would fail validation. We add a
migration which will look explcitily for the failing value and switch it
to the new default.

Change-type: patch
Signed-off-by: Cameron Diver <cameron@balena.io>

src/migrations/M00003.js

@@ -0,0 +1,21 @@
+exports.up = function(knex) {
+	return knex('deviceConfig')
+		.select('targetValues')
+		.then(([target]) => {
+			const targetValues = target.targetValues;
+			const jsonValues = JSON.parse(targetValues);
+
+			if (jsonValues['SUPERVISOR_DELTA_APPLY_TIMEOUT'] === '') {
+				jsonValues['SUPERVISOR_DELTA_APPLY_TIMEOUT'] = '0';
+
+				// Only update the database if we need to
+				return knex('deviceConfig').update({
+					targetValues: JSON.stringify(jsonValues),
+				});
+			}
+		});
+};
+
+exports.down = function(knex, Promise) {
+	return Promise.reject(new Error('Not Implemented'));
+};