Gatsby rehype plugin that rewrites URLs of src/href attributes.

yarn add gatsby-transformer-rehype @suin/gatsby-rehype-replace-urls

// In your gatsby-config.js
module.exports = {
  plugins: [
    {
      resolve: `gatsby-transformer-rehype`,
      options: {
        plugins: [
          {
            resolve: '@suin/gatsby-rehype-replace-urls',
            options: {
              replace({ url }) {
                const u = new URL(url)
                if (u.protocol === 'http:') {
                  u.protocol = 'https'
                }
                return u
              },
            },
          },
        ],
      },
    },
  ]
}

• To know the parameter of the replace function, see API doc.
• To learn more examples, see index.test.ts.