Google Cloud Managed Instance Groups Stateful

Step-01: Introduction¶

Instance Group: An instance group is a collection of virtual machine (VM) instances that you can manage as a single entity.
Instance Groups Types
1. Unmanaged Instance Group
2. Load Balancing
3. Managed Instance Group (Stateless)
4. Autoscaling
5. Autohealing
6. Auto-updating
7. Multi-Zone Deployment
8. Load Balancing
9. Managed Instance Group (Stateful)
10. Autohealing and updating
11. Disk and Metadata Preservation
12. Multi-Zone Deployment
13. Load Balancing
In this demo, we are going to focus on Managed Instance Groups - Stateful

Step-02: Create Health Check¶

What is Health Check?
1. A health check determines whether a VM instance is healthy by sending requests to the instance.
2. An instance is considered healthy if it returns consecutive responses within a specified time.
3. Health checks are used for load balancing and autoscaling managed instance groups
Go to Compute Engine -> Instance Groups -> Health Checks -> CREATE HEALTH CHECK
Name: app1-health-check
Description:
Scope: Regional
Region: us-central-1 (IOWA)
Protocol: HTTP
Port: 80
Proxy Protocol: None
Request Path: /app1/status.html
Response: App1
Host HTTP Header: leave empty (leave to defaults)
Logs: Off (leave to defaults) If enabled Cloud Logging cost is going to be high

Health Criteria: Leave to defaults

# Create Health Check
gcloud compute health-checks create http app1-health-check \
   --project=gcplearn9 \
   --port=80 \
   --request-path=/index.html \
   --proxy-header=NONE \
   --response=App1 \
   --region=us-central1 \
   --no-enable-logging \
   --check-interval=10 \
   --timeout=5 \
   --unhealthy-threshold=3 \
   --healthy-threshold=2

Click on CREATE

Step-03: Create a firewall rule to allow health check probes to connect to your app¶

Health check probes come from addresses in the ranges 130.211.0.0/22 and 35.191.0.0/16, so make sure your firewall rules allow the health check to connect. For this example, the MIG uses the default network, and its VMs listen on port 80. If port 80 isn't already open on the default network, create a firewall rule.
```
# Create Firewall rule
gcloud compute firewall-rules create allow-health-check \
    --allow tcp:80 \
    --source-ranges 130.211.0.0/22,35.191.0.0/16 \
    --network default
```

Step-04: Create Instance Template with additional persistent disk¶

Go to Compute Enginer -> Virtual Machines -> Instance Templates -> Create Instance Template
Name: mig-it-stateful
Location: Regional
Region: us-central1
Machine Configuration:
Series: E2
Machine Type: e2-micro
Availability Policies:
VM Provisioning Model: Standard
Display Device: unchecked (leave to default)
Confidential VM Service: unchecked (leave to default)
Container: unchecked (leave to default)
Boot Disk: Leave to defaults
Identity and API Access:
Service Account: Compute Engine default Service Account
Access Scopes: Allow default Access
Firewall
Allow HTTP Traffic
Advanced Options
Management:
- Description: demo4-vm-startupscript
- Reservations: Automatically use created reservation (leave to default)
- Automation:
- Startup Script: Copy paste content from webserver-install.sh file
CLick on disks
Additional disks: Click on Add new disk
Name: autogenerated
Description: persistent-disk-1
Type: Balanced persistent disk
Source type: Blank disk
Mode: Read/Write
Deletion rule: Keep disk / Delete disk (Even if we put delete disk also when we create stateful MIG, this setting will be override)
Size(GB): 12
Device name: Custom
name: persistent-disk-1
Click on Done
Click on CREATE

Step-05: Create Managed Instance Group Stateful Single Zone¶

Persistent Disks¶

Disk will be preserved during VM lifetime. It will be reattached on instance recreation, autohealing, and update events, and deleted on permanent instance deletion.

Persistent Internal and External IPs¶

IP will be preserved during VM lifetime. It will be reattached on instance recreation, autohealing, and update events, and deleted on permanent instance deletion.

Create Managed Instance Group - Stateful¶

Name: mig-stateful
Description: mig-stateful
Location: Single Zone
Region: us-central1
Zone: us-central1-a
Instance Template: mig-it-stateful
Number of Instances: 2
Stateful configuration:
Persistent-disk-1:
DEVICE NAME: persistent-disk-1
Stateful: YES
On permanent instance deletion: Detach disk
Yes: Disk will be preserved during VM lifetime. It will be reattached on instance recreation, autohealing, and update events, and deleted on permanent instance deletion.
No: Disk will be detached on instance deletion.
*Note: The disk disk_persistent-disk-1 will be preserved beyond the VM’s lifetime. It will be reattached on instance recreation, autohealing, and update events, and detached on instance deletion.
External IP address:
Stateful: YES
NOTE: IP will be preserved during VM lifetime. It will be reattached on instance recreation, autohealing, and update events, and deleted on permanent instance deletion.
On permanent instance deletion: DETACH IP
Note: IP from default network will be preserved beyond the VM’s lifetime. It will be reattached on instance recreation, autohealing, and update events, and detached on instance deletion.
Internal IP address:
Stateful: YES
NOTE: IP will be preserved during VM lifetime. It will be reattached on instance recreation, autohealing, and update events, and deleted on permanent instance deletion.
On permanent instance deletion: DETACH IP
Note: IP from default network will be preserved beyond the VM’s lifetime. It will be reattached on instance recreation, autohealing, and update events, and detached on instance deletion.
VM Instance lifecycle: leave to defaults
Action on failure: Repair instance
Autohealing:
Health check: app1-health-check
Initial Delay: 300 seconds
Updates during VM instance repair: Keep the same instance configuration
Specify Port Name Mapping:
Port Name: webserver-port
Port Numbers: 80
Advanced creation options: leave to defaults and discuss
Click on CREATE

Step-06: Review Managed Instance Group Properties¶

Go to Compute Engine -> Instance Groups -> Verify Group Type Stateful
Go to Compute Engine -> Instance Groups -> Click on mig-stateful
Review the following Tabs
Overview
Details
Monitoring
Errors (Not applicable for Unmanaged Instance Groups)
Go to Compute Engine -> VM Instances -> Verify VM created by Instance Group
Go to Compute Engine -> Disks -> Verify Disks created for Stateful Instance Group.

Step-07: Delete Stateful Managed Instance Group Stateful¶

Go to Compute Engine -> Instance Groups -> Click on mig-stateful
Click on DELETE GROUP
Go to Compute Engine -> Disks -> Verify Disks created for Stateful Instance Group.
```
# Sample disk name format
mig-stateful-wgh6-1
```
Even after deleting the Stateful Instance Group, we can see disks are still present because they got detached and persisted

Step-08: Clean-Up - Delete Disk¶

Delete the disk whatever created as per this demo.
Go to Compute Engine -> Disks -> mig-stateful-wgh6-1 -> Actions -> Delete
```
# Sample disk name format
managed-instance-group-stateful-wgh6-1
```

Step-09: Delete External and Internal IP¶

Go to VPC Network -> IP Addresses
Release External and Internal IP addresses

References¶

Instance Groups