Instance groups are collections of virtual machine (VM) instances that you can manage as a single entity.
Instance groups can help you simplify the management of multiple instances, reduce operational costs, and improve the availability and performance of your applications. Instance groups support autoscaling, which automatically adds or removes instances from the group based on increases or decreases in load. Autoscaling helps your applications gracefully handle increases in traffic and reduces cost when the need for resources is lower. You can set the autoscaling policy based on CPU utilization, load balancing capacity, Cloud Monitoring metrics, or a queue-based workload. In this case, since the video encoding software is CPU-intensive, setting the autoscaling based on CPU utilization is the best option to ensure high availability and optimal performance. References:
* Instance groups
* Autoscaling groups of instances

Installing Jenkins
In this section, you use Cloud Marketplace to provision a Jenkins instance. You customize this instance to use the agent image you created in the previous section.
Go to the Cloud Marketplace solution for Jenkins.
Click Launch on Compute Engine.
Change the Machine Type field to 4 vCPUs 15 GB Memory, n1-standard-4.
Machine type selection for Jenkins deployment.
Click Deploy and wait for your Jenkins instance to finish being provisioned. When it is finished, you will see:
Jenkins has been deployed.
https://cloud.google.com/solutions/using-jenkins-for-distributed-builds-on-compute-engine#installing_jenkins

https://cloud.google.com/iam/docs/job-functions/auditing#scenario_external_auditors Because if you directly add users to the IAM roles, then if any users left the organization then you have to remove the users from multiple places and need to revoke his/her access from multiple places. But, if you put a user into a group then its very easy to manage these type of situations. Now, if any user left then you just need to remove the user from the group and all the access got revoked The organization creates a Google group for these external auditors and adds the current auditor to the group.
This group is monitored and is typically granted access to the dashboard application. During normal access, the auditors' Google group is only granted access to view the historic logs stored in BigQuery. If any anomalies are discovered, the group is granted permission to view the actual Cloud Logging Admin Activity logs via the dashboard's elevated access mode. At the end of each audit period, the group's access is then revoked. Data is redacted using Cloud DLP before being made accessible for viewing via the dashboard application. The table below explains IAM logging roles that an Organization Administrator can grant to the service account used by the dashboard, as well as the resource level at which the role is granted.