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render-domains

Skill1 starsChanged 7 months agoMITView on GitHub

Configures custom domains and TLS certificates on Render—DNS setup, CNAME records, apex domains, wildcard domains, and certificate troubleshooting. Use when the user needs to add a custom domain, configure DNS, set up HTTPS/TLS, troubleshoot certificate issuance, disable the onrender.com subdomain, or add a wildcard domain. Trigger terms: custom domain, DNS, CNAME, TLS, SSL, HTTPS, certificate, apex domain, wildcard domain, onrender.com, domain verification.

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We split this skill into the rules it gives an agent

8 rules. About 0 are common, 2 are distinctive, and 6 are very specific to this project.

  • ≈0

    Common · estimate

    Many files like this have a rule of this kind.

  • ≈2

    Distinctive · estimate

    This author's own choices. Worth a look.

  • 6

    Very specific

    Tied to their project's names, files or tools. Probably skip.

  • Common
  • Distinctive
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  1. Very specific:

    Disabling the onrender.com subdomain: after adding a custom domain

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  2. Distinctive:

    Add a DNS record with your provider pointing to your Render service:

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  3. Very specific:

    Important: Remove any AAAA (IPv6) records for your domain.

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  4. Distinctive:

    After verification, Render issues a TLS certificate automatically.

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  5. Very specific:

    Cloudflare users: If you add *.example.com without adding the root domain to Render, disable proxying (gray cloud) for the root domain to …

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  6. Very specific:

    If your domain has CAA records, add entries for Render's certificate authorities:

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  7. Very specific:

    After adding at least one custom domain, you can disable the default onrender.com subdomain:

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  8. Very specific:

    All requests to the onrender.com URL receive a 404

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≈ “Common” is an estimate: at least 1 in 5 of the 350,495 skill files we read have a rule of the same kind, not the same words. “Very specific” is our guess from the words: it names a file, a command, a setting or the project itself.

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Files
SKILL.md

Render Custom Domains

Render automatically provisions and renews TLS certificates (via Let's Encrypt and Google Trust Services) for all custom domains. All HTTP traffic is redirected to HTTPS. Custom domains work on web services and static sites only.

When to Use

  • Adding a custom domain to a web service or static site
  • Configuring DNS records (CNAME, A, or ALIAS) with a provider
  • Setting up a wildcard domain (*.example.com)
  • Troubleshooting certificate issuance or domain verification failures
  • Choosing between apex (example.com) and www (www.example.com)
  • Disabling the onrender.com subdomain after adding a custom domain

Domain Limits and Cost

Workspace plans include a limited number of custom domains. Adding domains beyond the included allowance incurs an additional cost. Confirm current allowances and charges at Render pricing or in the Dashboard.

Setup Steps

1. Add domain in Dashboard

  1. Go to your service's Settings > Custom Domains
  2. Click + Add Custom Domain
  3. Enter your domain (e.g. app.example.com)
  4. Click Save

Adding a www subdomain automatically adds the root domain (and vice versa) with a redirect between them.

2. Configure DNS

Add a DNS record with your provider pointing to your Render service:

Domain typeRecord typeNameValue
Subdomain (app.example.com)CNAMEapp<service>.onrender.com
Apex (example.com) on CloudflareCNAME (flattened)@<service>.onrender.com
Apex on other providersA@Use Render-provided IP (see Dashboard)

Important: Remove any AAAA (IPv6) records for your domain. Render uses IPv4, and stale AAAA records cause unexpected behavior.

Provider-specific guides:

3. Verify domain

Click Verify in the Dashboard. If verification fails, DNS may not have propagated yet—wait a few minutes and retry.

Speed up verification by flushing DNS caches:

After verification, Render issues a TLS certificate automatically.

Wildcard Domains

Wildcard domains (*.example.com) route all matching subdomains to one service.

Requires three CNAME records:

NameValuePurpose
*<service>.onrender.comRoutes traffic
_acme-challenge<service-id>.verify.renderdns.comLet's Encrypt validation
_cf-custom-hostname<service-id>.hostname.renderdns.comCloudflare DDoS validation

Cloudflare users: If you add *.example.com without adding the root domain to Render, disable proxying (gray cloud) for the root domain to avoid routing conflicts.

CAA Records

If your domain has CAA records, add entries for Render's certificate authorities:

example.com IN CAA 0 issue "letsencrypt.org"
example.com IN CAA 0 issuewild "letsencrypt.org"
example.com IN CAA 0 issue "pki.goog; cansignhttpexchanges=yes"
example.com IN CAA 0 issuewild "pki.goog; cansignhttpexchanges=yes"

Without these, TLS certificate issuance fails silently.

Disabling the onrender.com Subdomain

After adding at least one custom domain, you can disable the default onrender.com subdomain:

  1. Settings > Custom Domains > Render Subdomain > toggle to Disabled
  2. All requests to the onrender.com URL receive a 404
  3. Can be re-enabled at any time

Blueprint Configuration

Custom domains are specified in the domains field:

services:
  - type: web
    name: api
    runtime: node
    plan: starter
    domains:
      - app.example.com
      - www.example.com

Blueprint domains only declare the domain association. You still need to configure DNS with your provider manually.

Common Mistakes

MistakeFix
AAAA records presentRemove all IPv6 AAAA records for the domain
CAA records blocking issuanceAdd letsencrypt.org and pki.goog entries
Verifying too quicklyWait 2-5 minutes for DNS propagation, then flush caches
Cloudflare proxy + wildcard without root domainDisable proxying (gray cloud) for the root domain
Trying to add domain to a private serviceCustom domains only work on web services and static sites
502 after verificationRouting rules are updating — wait a few minutes

References

DocumentContents
references/dns-configuration.mdProvider-specific DNS setup, apex domain options, TTL recommendations

Related Skills

  • render-web-services — Web service configuration, TLS, port binding
  • render-static-sites — Static site domains, CDN, headers
  • render-blueprints — domains field in render.yaml

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