Managed instance groups offer autoscaling capabilities that let you automatically add or delete instances from a managed instance group based on increases or decreases in load (CPU Utilization in this case). Autoscaling helps your apps gracefully handle increases intraffic and reduce costs when the need for resources is lower.
You define the autoscaling policy and the autoscaler performs automatic scaling based on the measured load (CPU Utilization in this case). Autoscaling works by adding more instances to your instance group when there is more load (upscaling), and deleting instances when the need for instances is lowered (downscaling). Ref:
https://cloud.google.com/compute/docs/autoscaler

Reference: https://cloud.google.com/solutions/using-jenkins-for-distributed-builds-on-compute-engine

"...we recommend that you enable Cloud Billing data export to BigQuery at the same time that you create a Cloud Billing account. " https://cloud.google.com/billing/docs/how-to/export-data-bigquery
https://medium.com/google-cloud/analyzing-google-cloud-billing-data-with-big-query-30bae1c2aae4

gcloud compute ssh ensures that the user's public SSH key is present in the project's metadata. If the user does not have a public SSH key, one is generated using ssh-keygen and added to the project's metadata. This is similar to the other option where we copy the key explicitly to the project's metadata but here it is done automatically for us. There are also security benefits with this approach. When we use gcloud compute ssh to connect to Linux instances, we are adding a layer of security by storing your host keys as guest attributes.
Storing SSH host keys as guest attributes improve the security of your connections by helping to protect against vulnerabilities such as man-in-the-middle (MITM) attacks. On the initial boot of a VM instance, if guest attributes are enabled, Compute Engine stores your generated host keys as guest attributes.
Compute Engine then uses these host keys that were stored during the initial boot to verify all subsequent connections to the VM instance.
Ref: https://cloud.google.com/compute/docs/instances/connecting-to-instance Ref: https://cloud.google.com/sdk/gcloud/reference/compute/ssh