market/gatsby-node.js

const createFields = require('./gatsby/createFields')
const createMarkdownPages = require('./gatsby/createMarkdownPages')

exports.onCreateNode = ({ node, actions, getNode }) => {
  createFields(node, actions, getNode)
}

exports.createPages = async ({ graphql, actions }) => {
  await createMarkdownPages(graphql, actions)
}

exports.onCreatePage = async ({ page, actions }) => {
  const { createPage } = actions
  // page.matchPath is a special key that's used for matching pages
  // only on the client.
  const handleClientSideOnly = page.path.match(/^\/asset/)

  if (handleClientSideOnly) {
    page.matchPath = '/asset/*'

    // Update the page.
    createPage(page)
  }
}

exports.onCreateWebpackConfig = ({ actions }) => {
  actions.setWebpackConfig({
    node: {
      // 'fs' fix for squid.js
      fs: 'empty'
    },
    // fix for 'got'/'swarm-js' dependency
    externals: ['got']
  })
}