Private Google Access in GCP - Step-by-Step Execution

Process Flow - Private Google Access

Create VPC Network

↓

Create Subnet in VPC

↓

Enable Private Google Access on Subnet

↓

VM in Subnet without Public IP

↓

VM sends request to Google API

↓

Request routed via Google internal network

↓

VM accesses Google services privately

↓

No public internet needed

This flow shows how enabling Private Google Access on a subnet lets VMs without public IPs reach Google services privately through Google's network.

Execution Sample

GCP

resource "google_compute_subnetwork" "subnet" {
  name          = "my-subnet"
  ip_cidr_range = "10.0.0.0/24"
  region        = "us-central1"
  network       = google_compute_network.vpc.id
  private_ip_google_access = true
}

This code creates a subnet with Private Google Access enabled, allowing VMs without public IPs to reach Google APIs privately.

Process Table

Step	Action	Resource State	Network Behavior	Result
1	Create VPC network	VPC network exists	No subnets yet	Ready for subnet creation
2	Create subnet without Private Google Access	Subnet exists, private_ip_google_access=false	VMs cannot access Google APIs privately	VMs need public IP or NAT
3	Enable Private Google Access on subnet	Subnet updated, private_ip_google_access=true	Subnet allows private access to Google APIs	VMs without public IP can access Google APIs
4	Launch VM without public IP in subnet	VM running, no public IP	VM routes Google API requests internally	VM accesses Google services privately
5	VM sends request to Google API	Request sent	Routed via Google internal network	Request succeeds without public internet
6	VM tries to access internet directly	Request sent	No public IP, no NAT	Request fails - no internet access
7	End	Infrastructure stable	Private Google Access active	VMs access Google APIs privately, no public internet needed

💡 Execution stops after VM accesses Google APIs privately without public internet access.

Status Tracker

Variable	Start	After Step 2	After Step 3	After Step 4	Final
private_ip_google_access	undefined	false	true	true	true
VM public IP	undefined	undefined	undefined	none	none
VM Google API access	undefined	no	yes	yes	yes

Key Moments - 3 Insights

Why can't a VM without a public IP access Google APIs before enabling Private Google Access?

Because without Private Google Access, the subnet does not route Google API requests internally, so the VM needs a public IP or NAT to reach Google services (see execution_table step 2).

Does enabling Private Google Access give the VM full internet access?

No, it only allows access to Google APIs via Google's internal network. The VM still cannot access the public internet without a public IP or NAT (see execution_table step 6).

What changes in the subnet configuration enable private access to Google APIs?

Setting 'private_ip_google_access' to true on the subnet enables routing of Google API requests through Google's internal network (see execution_table step 3).

Visual Quiz - 3 Questions

Look at the execution table, at which step is Private Google Access enabled on the subnet?

A Step 2

B Step 3

C Step 4

D Step 5

💡 Hint

Check the 'Action' and 'Resource State' columns in the execution_table rows.

According to the variable tracker, what is the VM's public IP status after step 4?

A No public IP

B Public IP unknown

C Has a public IP

D Public IP assigned later

💡 Hint

Look at the 'VM public IP' row under 'After Step 4' in variable_tracker.

If Private Google Access was not enabled, what would happen when the VM tries to access Google APIs?

A Request succeeds via internal network

B Request succeeds using public IP

C Request fails without public IP or NAT

D Request is blocked by firewall

💡 Hint

Refer to execution_table step 2 and step 6 for network behavior without Private Google Access.

Concept Snapshot

Private Google Access allows VMs without public IPs to reach Google APIs privately.
Enable it by setting 'private_ip_google_access = true' on a subnet.
VMs in that subnet route Google API requests via Google's internal network.
This does NOT provide general internet access.
Useful for secure, private access to Google services.

Full Transcript

Private Google Access is a feature in Google Cloud that lets virtual machines without public IP addresses access Google APIs and services privately. The process starts by creating a VPC network and a subnet. By enabling the 'private_ip_google_access' setting on the subnet, VMs launched inside it can send requests to Google APIs through Google's internal network, even if they do not have public IPs. This setup ensures that the VM's requests to Google services do not go through the public internet, enhancing security. However, this does not grant the VM access to the general internet; for that, a public IP or NAT is still required. The execution table traces these steps, showing how the subnet and VM states change, and how network behavior allows private access to Google APIs. The variable tracker monitors key variables like the private IP access flag and VM public IP status. Key moments clarify common confusions, such as the difference between private Google access and full internet access. The visual quiz tests understanding by referencing specific steps and variable states.

Practice

1. What is the main purpose of Private Google Access in Google Cloud?

easy

A. Provide a VPN connection between Google Cloud and on-premises networks

B. Allow VMs with only private IPs to access Google APIs without using the public internet

C. Allow external users to access Google Cloud resources securely

D. Enable VMs to have public IP addresses automatically

Solution

1. Step 1: Understand Private Google Access purpose

   It allows virtual machines without public IP addresses to reach Google APIs and services securely.

2. Step 2: Compare options with this purpose

   Only Allow VMs with only private IPs to access Google APIs without using the public internet describes this feature correctly; others describe unrelated features.

3. Final Answer:

   Allow VMs with only private IPs to access Google APIs without using the public internet -> Option B

4. Quick Check:

   Private Google Access = Secure private VM API access [OK]

Hint: Private Google Access = private VM access to Google APIs [OK]

Common Mistakes:

• Confusing Private Google Access with VPN or public IP assignment
• Thinking it allows external user access
• Assuming it provides public IPs automatically

2. Which configuration enables Private Google Access on a subnet in Google Cloud?

easy

A. Set private_ip_google_access = false in the subnet settings

B. Enable firewall rule to allow all traffic

C. Assign a public IP to all VMs in the subnet

D. Set private_ip_google_access = true in the subnet settings

Solution

1. Step 1: Identify the correct subnet setting for Private Google Access

   The subnet must have private_ip_google_access set to true to enable this feature.

2. Step 2: Review options for correctness

   Only Set private_ip_google_access = true in the subnet settings correctly sets private_ip_google_access to true; others disable it or are unrelated.

3. Final Answer:

   Set private_ip_google_access = true in the subnet settings -> Option D

4. Quick Check:

   Enable private_ip_google_access = true [OK]

Hint: Enable private_ip_google_access = true on subnet [OK]

Common Mistakes:

• Setting private_ip_google_access to false
• Thinking public IPs are required
• Confusing firewall rules with Private Google Access

3. Given a VM in a subnet with private_ip_google_access = true and no public IP, what happens when it tries to reach https://storage.googleapis.com?

medium

A. The VM accesses the URL through Private Google Access without using the public internet

B. The VM accesses the URL only if a VPN is configured

C. The VM cannot reach the URL because it has no public IP

D. The VM must use a NAT gateway to reach the URL

Solution

1. Step 1: Understand Private Google Access behavior

   With private_ip_google_access enabled, VMs without public IPs can reach Google APIs like storage.googleapis.com privately.

2. Step 2: Analyze options based on this behavior

   The VM accesses the URL through Private Google Access without using the public internet correctly describes this private access; others incorrectly deny access or require VPN/NAT.

3. Final Answer:

   The VM accesses the URL through Private Google Access without using the public internet -> Option A

4. Quick Check:

   Private IP VM + private_ip_google_access = private API access [OK]

Hint: Private IP VM with private_ip_google_access can reach Google APIs [OK]

Common Mistakes:

• Assuming no access without public IP
• Thinking VPN or NAT is mandatory
• Confusing Private Google Access with general internet access

4. A subnet has private_ip_google_access set to false. A VM without a public IP in this subnet cannot reach Google APIs. What is the best fix?

medium

A. Create a firewall rule to allow all outbound traffic

B. Assign a public IP to the VM

C. Enable private_ip_google_access = true on the subnet

D. Configure a VPN to Google Cloud

Solution

1. Step 1: Identify cause of no access

   Private Google Access is disabled, so private IP VMs cannot reach Google APIs.

2. Step 2: Choose the best fix

   Enabling private_ip_google_access on the subnet allows private IP VMs to access Google APIs without public IPs.

3. Final Answer:

   Enable private_ip_google_access = true on the subnet -> Option C

4. Quick Check:

   Enable private_ip_google_access to fix private VM API access [OK]

Hint: Enable private_ip_google_access = true to fix private VM API access [OK]

Common Mistakes:

• Assigning public IPs unnecessarily
• Adding firewall rules that don't affect Private Google Access
• Thinking VPN is required for Google API access

5. You have two subnets: Subnet A with private_ip_google_access = true and Subnet B with it set to false. A VM in Subnet B without a public IP needs to access Google APIs securely. What is the best approach?

hard

A. Move the VM to Subnet A or enable private_ip_google_access on Subnet B

B. Assign a public IP to the VM in Subnet B

C. Set up a NAT gateway for Subnet B

D. Create a firewall rule allowing access to Google APIs

Solution

1. Step 1: Understand subnet settings impact

   Private Google Access must be enabled on the subnet for private IP VMs to reach Google APIs.

2. Step 2: Evaluate options for secure access

   Moving the VM to Subnet A or enabling private_ip_google_access on Subnet B ensures secure private access without public IPs.

3. Step 3: Consider security and best practice

   Assigning public IPs or NAT gateways exposes the VM to public internet, less secure than Private Google Access.

4. Final Answer:

   Move the VM to Subnet A or enable private_ip_google_access on Subnet B -> Option A

5. Quick Check:

   Enable private_ip_google_access or move VM for secure private API access [OK]

Hint: Enable private_ip_google_access or move VM to subnet with it enabled [OK]

Common Mistakes:

• Assigning public IPs unnecessarily
• Relying on firewall rules alone
• Ignoring subnet configuration for Private Google Access