getUserServer.js

// [GET USER FROM SERVER]
export const getUserServer = ({ commit }, { req }) => {
  return new Promise(resolve => {
    if (!req || !req.headers.cookie) resolve('no cookie')
    // [берем refresh token]
    const refresh = Cookie.parse(req.headers.cookie).refresh || ''
    // [создаем ссылку для axios]
    const refreshLink = `https://securetoken.googleapis.com/v1/token?key=${projectID}`
    // [обновляем токен]
    const updateToken = axios.post(refreshLink, {
      grant_type: 'refresh_token',
      refresh_token: refresh
    })
    updateToken
      .then(res => {
        const NEW_TOKEN = res.data.access_token || ''
        const NEW_UID = res.data.user_id || ''
        const NEW_REFRESH = res.data.refresh_token || ''
        if (NEW_TOKEN === '' || NEW_UID === '' || NEW_REFRESH === '') return
        const ref =
          database.child('users').child(NEW_UID).toString() +
          `.json?auth=${NEW_TOKEN}`

        axios
          .get(ref)
          .then(res => {
            console.log(res.data)
            commit('SET_USER', res.data)
            resolve('done')
          })
          .catch(error => {
            console.log(error.response.status, error.response.statusText)
            resolve('error')
          })
      })
      .catch(error => {
        console.log(error.response.status, error.response.statusText)
        resolve('error')
      })
  })
}

middleware.js

export default ({ store, req, isServer }) => {
  if (isServer) {
    return store.dispatch('getUserServer', { req })
  }
  console.log('to client')
  return store.dispatch('getUser')
}

mutations.js

 SET_USER: function (state, user) {
    state.authUser = user
  },
  SET_TOKEN: (state, authCookies) => {
    const keys = Object.keys(authCookies)
    if (!inBrowser || !keys || !authCookies.token) return

    keys.forEach(cookieName => {
      Cookies.set(cookieName, authCookies[cookieName])
    })
  },

state.js

export default () => ({
  authUser: null,
  keys: null,
  confident: null
})

template.vue

<template>
  <h1>
    {{ $store.state.authUser }}</h1>
</template>
<script>
  export default {
    name: 'vueheader'
  }
</script>