push

push implements init by calling the @aerogear/core ConfigurationService at https://github.com/aerogear/aerogear-js-sdk/blob/964a45b0a851720410b68958774ed0f97e7d6785/packages/push/src/PushRegistration.ts#L23

auth

Same with auth at https://github.com/aerogear/aerogear-js-sdk/blob/964a45b0a851720410b68958774ed0f97e7d6785/packages/auth/src/Auth.ts#L17

sync

and sync is slightly different at but uses a similar pattern https://github.com/aerogear/aerogear-js-sdk/blob/964a45b0a851720410b68958774ed0f97e7d6785/packages/sync/src/config/SyncConfig.ts#L26