gatsby-node.js

const path = require("path")

exports.createPages = async ({ actions, graphql, reporter }) => {
  const { createPage } = actions
  const blogPostTemplate = path.resolve(`src/templates/blog.js`)

  const result = await graphql(`
  {
    allMarkdownRemark(
      sort: { order: DESC, fields: [frontmatter___date] }
      limit: 1000
    ) {
      edges {
        node {
          frontmatter {
            path
          }
        }
      }
    }
  }
  `)

  if (result.errors) {
    reporter.panicOnBuild("Error while running GQL " + JSON.stringify(result.errors))
    return
  }

  result.data.allMarkdownRemark.edges.forEach(({ node }) => {
    createPage({
      path: node.frontmatter.path,
      component: blogPostTemplate,
      context: {},
    })
  })
}