Zero Downtime Migration to Gatsby Hosting – Gatsby

Need help getting a certificate? Read the doc on how to Generate a SSL Certificate with Greenlock.domains

Ensure that you've followed the initial directions for turning on Gatsby Hosting. If you haven't done so, follow the direction in Deploying to Gatsby Cloud Hosting.
Wait for your site to be deployed to Gatsby Hosting and verify that everything works on the provided domain: https://YOUR_SITE_PREFIX_HERE.gatsbyjs.io
Add your domain(s), but do not change DNS yet!
Upload your TLS certificate. You can read about how to do that in Adding a Custom SSL Certificate.
Verify that your site responds to the configured domain:

Replace example.com with your domain. Repeat for each domain you are adding.
```
curl -H "Host: example.com" https://YOUR_SITE_PREFIX_HERE.gatsbyjs.io  index.html
```
View the downloaded index.html file and verify that it shows what you expect.

☝️Javascript/images/navigation might not work, but the statically rendered content should show up.

Once you've verified that the content is displayed as expected, add or update your DNS records for the domains you've added. For more resources about adding DNS records, check out Adding a Custom Domain.