server.js

const SECRET="createaverystrongsecretthatalsoincludes2423412wdsa324e34e"
const server = new ApolloServer({
  schema,
  context: ({ req }) => {
    const { user } = req
    // the user and secret we are passing here is what we access in every resolver 
    return {
      user,
      SECRET,
    }
  },
})

// this is a simple middleware that will check when every request hits apollo server.
const authUser = async req => {
  const token = await req.headers['authentication']

  try {
    const { user } = await jwt.verify(token, process.env.SECRET)
    req.user = user
  } catch (error) {
    console.log(error) // or do something else with the error
  }
  req.next()
}
// now we can pass our middleware
appServer.use(authUser)