gatsby-node.js

const path = require('path')

module.exports.createPages = async ({ graphql, actions }) => {
  const { createPage } = actions
  const blogTemplate = path.resolve('./src/templates/blog.js')
  const res = await graphql(`
    query {
      allContentfulBlogPost {
        edges {
          node {
            slug
          }
        }
      }
    }
  `)

  res.data.allContentfulBlogPost.edges.forEach((edge) => {
    createPage({
      component: blogTemplate,
      path: `/blog/${edge.node.slug}`,
      context: {
        slug: edge.node.slug,
      },
    })
  })
}

exports.onCreateWebpackConfig = ({ stage, actions }) => {
  if (stage.startsWith('develop')) {
    actions.setWebpackConfig({
      resolve: {
        alias: {
          'react-dom': '@hot-loader/react-dom',
        },
      },
    })
  }
}