SSH access and metadata in GCP - Mini Project: Build & Apply

SSH Access and Metadata Configuration on GCP

📖 Scenario: You are setting up a Google Cloud virtual machine (VM) to allow secure SSH access for a user. You will configure the VM's metadata to include the SSH public key for that user. This setup is common when you want to control who can connect to your VM securely.

🎯 Goal: Configure the SSH access by adding the correct SSH public key to the VM instance metadata on Google Cloud Platform.

📋 What You'll Learn

Create a metadata dictionary with the SSH keys entry

Add a specific SSH public key string to the metadata

Assign the metadata to the VM instance configuration

Ensure the SSH key is correctly formatted in the metadata

💡 Why This Matters

🌍 Real World

Setting SSH keys in VM metadata is a common way to control who can securely connect to cloud virtual machines without sharing passwords.

💼 Career

Cloud engineers and system administrators often configure VM metadata to manage access and automate instance setup securely.

1

Create the initial metadata dictionary

Create a dictionary called metadata with a key "ssh-keys" and an empty string as its value.

GCP

# Create the metadata dictionary with ssh-keys key
# Your code here

Hint

Use curly braces to create a dictionary and set the value of "ssh-keys" to an empty string.

2

Add the SSH public key string to metadata

Add the SSH public key string "user:ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAABAQC7examplekey [e-mail]" as the value for the "ssh-keys" key in the metadata dictionary.

GCP

metadata = {"ssh-keys": ""}
# Add the SSH public key string to the ssh-keys key
# Your code here

Hint

Replace the empty string with the exact SSH public key string including the username and key.

3

Create the VM instance configuration dictionary

Create a dictionary called vm_instance with a key "metadata" and assign the metadata dictionary as its value.

GCP

metadata = {"ssh-keys": "user:ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAABAQC7examplekey [e-mail]"}
# Create vm_instance dictionary with metadata key
# Your code here

Hint

Use the metadata dictionary as the value for the metadata key inside vm_instance.

4

Add the final SSH access enable flag

Add a key "enable-ssh" with the value "true" to the metadata dictionary inside vm_instance to enable SSH access.

GCP

metadata = {"ssh-keys": "user:ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAABAQC7examplekey [e-mail]"}
vm_instance = {"metadata": metadata}
# Add enable-ssh key with value true to metadata
# Your code here

Hint

Add the enable-ssh key with the string value "true" inside the metadata dictionary.

Practice

1. What is the main purpose of SSH access in Google Cloud Platform (GCP)?

easy

A. To securely connect to virtual machine instances

B. To store large files in the cloud

C. To monitor network traffic

D. To create new virtual machines automatically

Solution

1. Step 1: Understand SSH access

   SSH (Secure Shell) is a protocol used to securely connect to remote machines, such as virtual machines in GCP.

2. Step 2: Identify SSH use in GCP

   In GCP, SSH access allows users to securely log into VM instances to manage and operate them.

3. Final Answer:

   To securely connect to virtual machine instances -> Option A

4. Quick Check:

   SSH access = secure VM connection [OK]

Hint: SSH is for secure remote login to VMs [OK]

Common Mistakes:

• Confusing SSH with storage or monitoring services
• Thinking SSH creates VMs instead of connecting to them

2. Which of the following is the correct way to add an SSH key to a VM instance's metadata in GCP?

easy

A. Add the SSH key to the project billing settings

B. Add the SSH key to the instance's firewall rules

C. Add the SSH key to the VM's disk storage

D. Add the SSH key to the instance's metadata under the 'ssh-keys' key

Solution

1. Step 1: Understand where SSH keys are stored

   SSH keys are stored in metadata, which is a place to keep configuration info for VMs.

2. Step 2: Identify correct metadata key

   The correct metadata key for SSH keys is 'ssh-keys' at the instance or project level.

3. Final Answer:

   Add the SSH key to the instance's metadata under the 'ssh-keys' key -> Option D

4. Quick Check:

   SSH keys stored in 'ssh-keys' metadata [OK]

Hint: SSH keys go in 'ssh-keys' metadata key [OK]

Common Mistakes:

• Adding SSH keys to firewall rules instead of metadata
• Trying to store SSH keys in disk storage or billing settings

3. Given the following metadata setup for a VM instance in GCP:

{"ssh-keys": "user:ssh-rsa AAAAB3Nza... [e-mail]"}

What will happen when you try to SSH into this VM as 'user'?

medium

A. SSH connection will succeed using the provided public key

B. SSH connection will be denied due to missing keys

C. SSH will prompt for a password instead of using keys

D. The VM will restart automatically

Solution

1. Step 1: Analyze the metadata content

   The metadata contains a valid SSH public key for user 'user' under 'ssh-keys'.

2. Step 2: Understand SSH key usage

   When connecting as 'user', the VM checks the 'ssh-keys' metadata and allows access if the matching private key is used.

3. Final Answer:

   SSH connection will succeed using the provided public key -> Option A

4. Quick Check:

   Valid SSH key in metadata = successful SSH login [OK]

Hint: Valid SSH key in metadata allows login [OK]

Common Mistakes:

• Assuming password prompt appears despite key presence
• Thinking VM restarts due to SSH metadata

4. You added an SSH key to your project-wide metadata but still cannot SSH into a VM instance. What is the most likely cause?

medium

A. The firewall allows SSH traffic

B. The VM instance is turned off

C. The instance has block-project-ssh-keys set to true, blocking project keys

D. The SSH key format is incorrect in the metadata

Solution

1. Step 1: Understand project-wide SSH keys

   Project-wide SSH keys apply to all instances unless blocked by instance settings.

2. Step 2: Check instance metadata blocking

   If the instance metadata has 'block-project-ssh-keys' set to true, it ignores project-wide keys.

3. Final Answer:

   The instance has block-project-ssh-keys set to true, blocking project keys -> Option C

4. Quick Check:

   block-project-ssh-keys=true blocks project keys [OK]

Hint: Check 'block-project-ssh-keys' flag on instance [OK]

Common Mistakes:

• Assuming firewall allows SSH means keys work
• Ignoring instance-level metadata blocking project keys

5. You want to ensure that only specific users can SSH into a VM instance in GCP, even though project-wide SSH keys exist. Which approach is best?

hard

A. Add all users' SSH keys to project metadata and leave instance metadata empty

B. Set 'block-project-ssh-keys' to true on the instance and add allowed users' keys to instance metadata

C. Remove all SSH keys from project metadata and rely on firewall rules

D. Disable SSH access entirely on the VM instance

Solution

1. Step 1: Understand project-wide vs instance metadata

   Project-wide SSH keys apply to all instances unless blocked by instance settings.

2. Step 2: Control access per instance

   Setting 'block-project-ssh-keys' to true on the instance disables project keys, allowing only instance metadata keys.

3. Step 3: Add allowed users' keys to instance metadata

   By adding only allowed users' keys to instance metadata, you restrict SSH access to them.

4. Final Answer:

   Set 'block-project-ssh-keys' to true on the instance and add allowed users' keys to instance metadata -> Option B

5. Quick Check:

   Block project keys + instance keys = controlled SSH access [OK]

Hint: Block project keys, use instance keys for control [OK]

Common Mistakes:

• Relying only on firewall rules for SSH user control
• Removing project keys without adding instance keys
• Disabling SSH entirely when access is needed