Custom domains in GCP - Step-by-Step Execution

Process Flow - Custom domains

User owns domain

↓

Verify domain ownership

↓

Create DNS records

↓

Map domain to GCP service

↓

GCP provisions SSL certificate

↓

User accesses service via custom domain

This flow shows how a user verifies their domain, sets DNS records, maps it to a GCP service, and accesses it securely.

Execution Sample

GCP

1. Verify domain ownership in GCP Console
2. Add DNS A and CNAME records at domain registrar
3. Map domain to App Engine or Cloud Run
4. Wait for SSL certificate provisioning
5. Access service via custom domain

Steps to connect a custom domain to a GCP service with secure HTTPS.

Process Table

Step	Action	Input/Condition	Result	Notes
1	Verify domain ownership	User submits domain	Ownership verified	GCP confirms user controls domain
2	Create DNS records	Add A and CNAME records	DNS records propagate	Propagation can take minutes to hours
3	Map domain to service	Select domain in GCP service settings	Domain linked to service	Service ready to respond to domain
4	Provision SSL certificate	Automatic by GCP	SSL certificate active	Enables HTTPS access
5	Access service	User visits custom domain URL	Service loads securely	Custom domain fully functional

💡 Process completes when SSL is active and service responds on custom domain

Status Tracker

Variable	Start	After Step 1	After Step 2	After Step 3	After Step 4	Final
Domain Ownership	Unverified	Verified	Verified	Verified	Verified	Verified
DNS Records	None	None	Created	Created	Created	Created and propagated
Domain Mapping	Not linked	Not linked	Linked	Linked	Linked	Linked
SSL Certificate	None	None	None	Provisioning	Provisioning	Active
Service Access	Unavailable	Unavailable	Unavailable	Unavailable	Unavailable	Available via custom domain

Key Moments - 3 Insights

Why do I need to verify domain ownership before mapping it?

Verification proves you control the domain, preventing others from linking your domain to their services. See execution_table step 1.

What happens if DNS records are not set correctly?

The domain won't point to your service, so users can't reach it. This is shown in execution_table step 2 where DNS records must be created and propagated.

Why does SSL certificate provisioning take time?

GCP requests certificates from trusted authorities, which can take minutes. Until active, HTTPS won't work. See execution_table step 4.

Visual Quiz - 3 Questions

Look at the execution_table, at which step is the domain ownership verified?

A Step 1

B Step 2

C Step 3

D Step 4

💡 Hint

Check the 'Result' column in step 1 for ownership verification.

According to variable_tracker, what is the state of SSL Certificate after Step 3?

A Active

B Provisioning

C None

D Expired

💡 Hint

Look at the SSL Certificate row under 'After Step 3' column.

If DNS records are not created, what will be the final state of Service Access?

A Available via custom domain

B Unavailable

C Partially available

D Redirected to default domain

💡 Hint

Refer to variable_tracker row 'DNS Records' and 'Service Access' to see dependency.

Concept Snapshot

Custom domains in GCP:
1. Verify domain ownership to prove control.
2. Add DNS A and CNAME records at your registrar.
3. Map domain to your GCP service (App Engine, Cloud Run).
4. GCP provisions SSL certificate automatically.
5. Access your service securely via your custom domain.

Full Transcript

To use a custom domain with a Google Cloud Platform service, first verify that you own the domain. This prevents unauthorized use. Then, create DNS records at your domain registrar to point the domain to your GCP service. Next, map the domain in your GCP service settings. GCP will then automatically provision an SSL certificate to enable secure HTTPS access. Finally, users can access your service using the custom domain securely. Each step changes the state of domain ownership verification, DNS records, domain mapping, SSL certificate status, and service accessibility.

Practice

1. What is the primary purpose of setting up a custom domain in Google Cloud Platform (GCP)?

easy

A. To use your own website address instead of a default GCP URL

B. To increase the storage capacity of your GCP project

C. To enable automatic backups for your cloud resources

D. To create virtual machines with custom names

Solution

1. Step 1: Understand what a custom domain is

   A custom domain lets you use your own website address instead of a generic cloud URL.

2. Step 2: Identify the purpose in GCP context

   In GCP, custom domains help users access services with familiar URLs, improving branding and trust.

3. Final Answer:

   To use your own website address instead of a default GCP URL -> Option A

4. Quick Check:

   Custom domain = personal website address [OK]

Hint: Custom domain means your own website address, not default URL [OK]

Common Mistakes:

• Confusing custom domain with storage or VM settings
• Thinking it changes backup or machine names
• Assuming it increases resource limits

2. Which DNS record type must you configure to point your custom domain to a Google App Engine service?

easy

A. MX record

B. TXT record

C. SRV record

D. CNAME record

Solution

1. Step 1: Identify DNS record types for domain pointing

   CNAME records map a domain or subdomain to another domain name, commonly used for pointing to cloud services.

2. Step 2: Match with Google App Engine requirements

   Google App Engine custom domains require CNAME records to link your domain to their service address.

3. Final Answer:

   CNAME record -> Option D

4. Quick Check:

   Point domain to service = CNAME record [OK]

Hint: Use CNAME to point domain to cloud service address [OK]

Common Mistakes:

• Using MX records which are for email routing
• Using TXT records meant for verification
• Confusing SRV records which are for service location

3. Given this snippet configuring a custom domain in GCP App Engine, what will happen if the DNS is not properly set?

gcloud app domain-mappings create example.com --certificate-management=automatic

medium

A. The command will fail with a syntax error

B. The domain will be mapped but users cannot access the app via example.com

C. The app will be accessible immediately without DNS changes

D. The SSL certificate will not be issued

Solution

1. Step 1: Understand domain mapping command effect

   The command creates a domain mapping and requests SSL certificate automatically.

2. Step 2: Consider DNS role in accessibility

   If DNS records do not point to GCP, users cannot reach the app via the custom domain despite mapping.

3. Final Answer:

   The domain will be mapped but users cannot access the app via example.com -> Option B

4. Quick Check:

   Mapping without DNS update = no access [OK]

Hint: Mapping alone doesn't work without DNS pointing [OK]

Common Mistakes:

• Assuming command fails without DNS
• Thinking app is accessible immediately
• Believing SSL won't issue without DNS

4. You tried to add a custom domain to your GCP App Engine app but received an error: "Domain ownership verification failed." What is the most likely cause?

medium

A. You did not add the required TXT record to your domain's DNS

B. You used an incorrect CNAME record type

C. Your App Engine app is not deployed

D. You forgot to enable billing on your GCP project

Solution

1. Step 1: Understand domain ownership verification process

   GCP requires you to prove you own the domain by adding a TXT record to DNS.

2. Step 2: Identify cause of verification failure

   If the TXT record is missing or incorrect, verification fails and domain cannot be added.

3. Final Answer:

   You did not add the required TXT record to your domain's DNS -> Option A

4. Quick Check:

   Missing TXT record = ownership verification fail [OK]

Hint: Verify domain by adding TXT record in DNS [OK]

Common Mistakes:

• Confusing CNAME with TXT for verification
• Assuming app deployment affects verification
• Thinking billing status causes verification error

5. You want to serve your website on both example.com and www.example.com using GCP App Engine with HTTPS. Which setup correctly achieves this with minimal manual DNS management?

hard

A. Map both domains; create TXT records for SSL; manually upload certificates

B. Map only example.com in App Engine; create A record for www pointing to example.com IP; manually manage SSL

C. Map both domains separately in App Engine and create CNAME for www pointing to ghs.googlehosted.com; use automatic SSL

D. Map www.example.com only; create CNAME for example.com pointing to www; disable SSL

Solution

1. Step 1: Understand domain mapping for root and www

   Both example.com and www.example.com need mapping to serve content on both URLs.

2. Step 2: Use recommended DNS and SSL setup

   Google recommends CNAME for www to ghs.googlehosted.com and automatic SSL management for ease and security.

3. Final Answer:

   Map both domains separately in App Engine and create CNAME for www pointing to ghs.googlehosted.com; use automatic SSL -> Option C

4. Quick Check:

   Separate mapping + CNAME + auto SSL = best practice [OK]

Hint: Map both domains and use CNAME for www with auto SSL [OK]

Common Mistakes:

• Using A record for www which is not recommended
• Mapping only one domain and missing the other
• Disabling SSL or managing certificates manually unnecessarily