axios.js

import axios from 'axios';
import config from 'src/config';

export default axios.create({
  baseURL: config.apiBaseUrl,
  timeout: 3000,
  headers: {
    'content-type': 'application/json'
  }
});

stores.js

import { createStore, applyMiddleware, compose } from 'redux';
import { createLogger } from 'redux-logger';
import thunk from 'redux-thunk';

import syncAxiosToken from './syncAxiosToken';
import ApplicationReducer from './reducers';

export default function (initialState = {}) {
  const loggerMiddleware = createLogger();
  const middleware = [thunk, loggerMiddleware];
  const store = createStore(
    ApplicationReducer,
    initialState,
    compose(
      applyMiddleware(...middleware)
    )
  );

  syncAxiosToken(store);

  return store;
}

syncAxiosToken.js

import watch from 'redux-watch';
import axios from 'src/axios';

export default (store) => {
  const w = watch(store.getState, 'auth.authentication');

  store.subscribe(w((token) => {
    const authorization = token ? `Bearer ${token}` : '';
    axios.defaults.headers.common.Authorization = authorization;
  }));
};