An unmanaged instance group is a collection of virtual machines (VMs) that reside in a single zone, VPC network, and subnet. An unmanaged instance group is useful for grouping together VMs that require individual configuration settings or tuning.
For VMs that require consistent configuration settings, you can use a managed instance group (MIG) that's based on an instance template. When possible, consider using managed instance groups instead of unmanaged ones. To create a managed instance group, see Create a MIG.
You can add either type of instance group as a backend to a Google Cloud load balancer. For more information, see Cloud Load Balancing overview. For the number of VMs per instance group that Cloud Load Balancing supports, see VMs per instance group.
To learn more about instance groups, see Instance groups overview.
Before you begin
- If you want to use the command-line examples in this guide, do the following:
- Install or update to the latest version of the Google Cloud CLI.
- Set a default region and zone.
- If you want to use the API examples in this guide, set up API access.
- Read about the difference between managed and unmanaged instance groups.
Working with unmanaged instance groups
Creating groups
Unlike managed instance groups, unmanaged instance groups are just collections of distinct VMs that do not share a common instance template. You simply create a group, and add individual VMs to the group.
Console
- In the Cloud console, go to the Instance groups page.
- Click Create instance group.
- Click New unmanaged instance group.
- Enter a name for the unmanaged instance group.
- Under Location, select a region and a zone.
- Select a Network and Subnetwork.
- Under VM instances, select the VMs to add to this group.
- Click Create.
gcloud
To create a new unmanaged instance group, use the instance-groups unmanaged create command:
gcloud compute instance-groups unmanaged create instance-group-name \ --zone=zone
Replace the following:
instance-group-name
: The name of the group you want to create.zone
: The zone where you want to create the group.
API
To create an unmanaged instance group with the API, send a POST
request using the
instanceGroups.insert
method:
POST https://compute.googleapis.com/compute/v1/projects/project-id/zones/zone/instanceGroups { "name": "instance-group-name" }
Replace the following:
instance-group-name
: The name of the group you want to create.zone
: The zone where you want to create the group.project-id
: The project ID for the project containing the group.
When you create a new unmanaged instance group with Google Cloud CLI or the API, no VMs are added to it automatically. You can add VMs to the unmanaged instance group manually.
Listing and describing groups
Retrieve a list of existing unmanaged instance groups.
Console
In the Cloud console, the Instance groups page lists existing unmanaged and managed instance groups.
gcloud
To list all unmanaged instance groups in your project with the Google Cloud CLI, use instance-groups unmanaged list:
gcloud compute instance-groups unmanaged list
To see information about a specific unmanaged instance group, use the instance-groups unmanaged describe command:
gcloud compute instance-groups unmanaged describe instance-group-name \ --zone=zone
Replace the following:
instance-group-name
: The name of the group to describe.zone
: The zone of the group.
API
To list instance groups with the API, send a GET
request using the
instanceGroups.list
method:
GET https://compute.googleapis.com/compute/v1/projects/project-id/zones/zone/instanceGroups
To obtain information about a specific unmanaged instance group with the
API, send a GET
request using the
instanceGroups.get
method:
GET https://compute.googleapis.com/compute/v1/projects/project-id/zones/zone/instanceGroups/instance-group-name
Replace the following:
instance-group-name
: The name of the group to describe.zone
: The zone of the group.project-id
: The project ID for the project containing the group.
Deleting groups
Unlike a managed instance group, deleting an unmanaged instance group does not delete any of the VMs within the group. Deleting an unmanaged instance group only removes the logical grouping of VMs.
You can't delete an instance group if the group is a backend of a Google Cloud load balancer. You must first remove the backend from the backend service.
Console
- In the Cloud console, go to the Instance groups page.
- Select one or more unmanaged instance groups from the list.
- Click Delete to remove the groups. The groups are removed, but the VMs in the groups are not deleted.
gcloud
To delete an unmanaged instance group, use the instance-groups unmanaged delete command:
gcloud compute instance-groups unmanaged delete instance-group-name \ --zone=zone
Replace the following:
instance-group-name
: The name of the group you want to delete.zone
: The zone of the group.
API
To delete an unmanaged instance group with the API, send a DELETE
request using the
instanceGroups.delete
method:
DELETE https://compute.googleapis.com/compute/v1/projects/project-id/zones/zone/instanceGroups/instance-group-name
Replace the following:
instance-group-name
: The name of the group you want to delete.zone
: The zone of the group.project-id
: The project ID for the project containing the group.
Group membership
Adding VMs
After you create an unmanaged instance group,
you can add VMs to the group. However, you can only group VMs together if
the first or only network interface (nic0
) of each VM is attached to the
same VPC network.
Console
- In the Cloud console, go to the Instance groups page.
- Under the Name column of the list, click the name of the instance group where you want to add your VMs. A page opens with the instance group properties and a list of VMs that are already part of the group.
- Click Edit to modify this unmanaged instance group.
- Under VM instances select one or more existing VMs to add to the group. You can only select VMs that are in the same zone, VPC network, and subnet as existing VMs.
- Click Save to add the new VMs to the group.
gcloud
To add instances to an unmanaged instance group, use the instance-groups unmanaged add-instances command:
gcloud compute instance-groups unmanaged add-instances instance-group-name \ --zone=zone \ --instances=list-of-VM-names
Replace the following:
instance-group-name
: The name of the group to which you want to add VMs.zone
: The zone of the group.list-of-VM-names
: A comma-delimited list of VMs in the same zone, VPC network, and subnet.
API
To add VMs to an unmanaged instance group with the API, send a POST
request using the
instanceGroups.addInstances
method:
POST https://compute.googleapis.com/compute/v1/projects/project-id/zones/zone/instanceGroups/instance-group-name/addInstances { "instances": [ { "instance": "https://www.googleapis.com/compute/v1/projects/project-id/zones/zone/instances/instance-1-name", "instance": "https://www.googleapis.com/compute/v1/projects/project-id/zones/zone/instances/instance-2-name", .... } ] }
Replace the following:
instance-group-name
: The name of the group to which you want to add VMs.zone
: The zone of the group.project-id
: The project ID for the project containing the group.instance-1-name
andinstance-2-name
: These are names of the VMs, in the same zone, VPC network, and subnet, that you want to add to the group.
Listing VMs
You can retrieve a list of member VMs in an unmanaged instance group.
Console
- In the Cloud console, go to the Instance groups page.
- Under the Name column of the list, click the name of the unmanaged instance group that you want to view. A page with the list of instances that are included in the group appears.
gcloud
To list the VMs in an unmanaged instance group, use the instance-groups unmanaged list-instances command:
gcloud compute instance-groups unmanaged list-instances instance-group-name \ --zone=zone
Replace the following:
instance-group-name
: The name of the group whose members you want to list.zone
: The zone of the group.
API
To list VMs in an unmanaged instance group with the API, send a POST
request using the
instanceGroups.listInstances
method:
POST https://compute.googleapis.com/compute/v1/projects/project-id/zones/zone/instanceGroups/instance-group-name/listInstances
Replace the following:
instance-group-name
: The name of the group whose members you want to list.zone
: The zone of the group.project-id
: The project ID for the project containing the group.
Removing VMs
You can remove VMs from an unmanaged instance group. Removing a VM from the instance group does not delete the VM.
Console
- In the Cloud console, go to the Instance groups page.
- Under the Name column of the list, click the name of the instance group from which you want to remove VMs. A page opens with the instance group properties and a list of VMs that are included in the group.
- In the list, select one or more VMs that you want to remove from the group.
- Click Remove from group. VMs that you remove from an unmanaged instance group continue to exist and run unless you stop or delete them.
gcloud
To remove VMs from an unmanaged instance group, use the instance-groups unmanaged remove-instances command:
gcloud compute instance-groups unmanaged remove-instances instance-group-name \ --zone=zone \ --instances=list-of-VM-names
Replace the following:
instance-group-name
: The name of the group that contains instances to remove.zone
: The zone of the group.list-of-VM-names
: A comma-delimited list of VMs that you want to remove from the group.
API
To remove VMs from an unmanaged instance group with the API, send a POST
request using the
instanceGroups.removeInstances
method. You can simultaneously remove multiple VMs as shown below:
POST https://compute.googleapis.com/compute/v1/projects/project-id/zones/zone/instanceGroups/instance-group-name/removeInstances { "instances": [ { "instance": "https://www.googleapis.com/compute/v1/projects/project-id/zones/zone/instances/instance-1-name", "instance": "https://www.googleapis.com/compute/v1/projects/project-id/zones/zone/instances/instance-2-name", .... } ] }
Replace the following:
instance-group-name
: The name of the group that contains instances to remove.zone
: The zone of the group.project-id
: The project ID for the project containing the group.instance-1-name
andinstance-2-name
: These are names of the VMs that you want to disassociate from the group.
Working with named ports
Named ports are key-value pairs that represent a port's name and number. The port name represents a name of a service or application. The port number represents the port that service or application runs on.
Named ports are used by Cloud Load Balancing. Load balancers that act as proxies subscribe to a single named port in their backend service configuration. The port's name is translated to a port number based on the named port's mapping of each instance group backend.
For example, a backend service can subscribe to a port that is named http-port
.
The backend instance group can have a port named http-port:80
. The backend
instance group instructs the load balancer to send traffic to a VM in the group
on port 80 using a protocol (such as TCP). The protocol is defined in the load
balancer's backend service.
Named ports are simple metadata used by proxy load balancers. Named ports do not control network or firewall resources in Compute Engine.
Multiple port numbers for a named port
You can assign multiple ports for each service name. You can also assign multiple service names for each port.
Keep in mind the following points:
- Traffic is balanced between all ports with the same port name.
- A given backend service can only forward traffic to one named port at a time.
If you use multiple port numbers for a named port, the ports must all be for the same application.
For example,
http:80,http:8080
works, buthttp:80,http:443
doesn't work because port 80 generally doesn't support TLS.
You can assign multiple named ports in an instance group. To illustrate,
consider an example backend service that subscribes to the named port
http-port
, and that has two backend instance groups:
instance-group-a
with a named port ofhttp-port:80
instance-group-b
with a named port ofhttp-port:79
This backend service sends traffic to port 80 for VMs in instance-group-a
and
port 79 for VMs in instance-group-b
.
When you add the same instance group to multiple backend services (for multiple load balancers) and the instance group serves different ports on each load balancer, don't add all the port numbers to a single named port. Instead create a unique named port and map it to a set of ports that each backend service should serve.
For example, suppose you have three applications, each with its own load
balancer. Each application has its own port number: 81 for app1
, 82
for app2
, and 83 for app3
. Assuming that all three backend services are
using a common instance group, assign the named ports for this instance group
as [app1:81, app2:82, app3:83]
.
Named ports and health checks
For a named port with multiple port numbers on a backend service to work in an
external HTTP(S) load balancer or internal HTTP(S) load balancer, the health check must have the
--use-serving-port
flag instead of a specific port number. This option is not
available in the Google Cloud console. You must use gcloud
or the API to set
--use-serving-port
.
For example, suppose you have an application that load balances the traffic on
three different ports (81, 82, 83) on the same backend service with a single
instance group. You can assign the ports for this instance groups as [app:81,
82, 83]
. The health check in this scenario must have the --use-serving-port
flag.
For more information, see the load balancing health check documentation.
Named ports and firewall rules
Named ports do not create or modify Google Cloud firewall rules. To permit traffic to backend VMs, you must still create the necessary firewall rules.
Named ports and backend services
In addition to the instance group configuration, you must also configure
the backend service. For example, suppose you set the named port on an instance
group with the name my-service-name
and the port 8888
:
gcloud compute instance-groups set-named-ports my-unmanaged-ig \ --named-ports=my-service-name:8888
Then you must refer to the named port in the backend service configuration with
the --port-name
on the backend service set to my-service-name
:
gcloud compute backend-services update my-backend-service \ --port-name=my-service-name
Creating named ports
Console
- In the Cloud console, go to the Instance groups page.
- Under the Name column of the list, click the name of the instance group where you want to specify named ports. A page opens with the instance group properties.
- Click Edit to modify this unmanaged instance group.
- In the Port mapping section, click Add port, and enter a port name and its number. Add or remove other named ports as necessary.
- Click Save to update the list of named ports for the unmanaged instance group.
gcloud
To add named ports to an unmanaged instance group, use the instance-groups
unmanaged set-named-ports
command:
gcloud compute instance-groups unmanaged set-named-ports instance-group-name \ --zone=zone \ --named-ports=port-name:port-number,...
To list named ports in an unmanaged instance group use the instance-groups unmanaged get-named-ports
command:
Set one or more named ports using the set-named-ports
command:
gcloud compute instance-groups unmanaged set-named-ports INSTANCE_GROUP \ --named-ports PORT_NAME:PORT,PORT_NAME:PORT
For example:
gcloud compute instance-groups unmanaged set-named-ports INSTANCE_GROUP \ --named-ports name1:80,name2:8080
To assign multiple ports to each service name or multiple names for each
service, create more than one entry for each name or port. For example, if
ports 10
, 20
, and 80
are for the same application, you can assign
name1
to all of those ports. Additionally, you might assign two names,
name2
and name3
to port 8080
. Finally, you might assign port 9000
to
name4
, as in the following example:
gcloud compute instance-groups unmanaged set-named-ports INSTANCE_GROUP \ --named-ports name1:10,name1:20,name1:80,\ name2:8080,name3:8080,\ name4:9000
To remove all named ports from an unmanaged instance group with the Google Cloud CLI, use instance-groups unmanaged set-named-ports with an empty list of named ports:
gcloud compute instance-groups unmanaged set-named-ports instance-group-name \ --zone=zone \ --named-ports=""
In all the examples above, replace the following if present:
instance-group-name
: The name of the instance group.zone
: The zone of the group.port-name
andport-number
: The port name and number represent a mapping from a name you choose to a port number. You can specify multiple mappings separated by commas; for example,port-one:80,port-two:8080
is a valid list of named ports.
API
Describe the instance group and note the fingerprint.
To add named ports with the API, send a
POST
request using the instanceGroups.setNamedPorts method. If you want to remove all named ports, setnamedPorts
to an empty list.POST https://compute.googleapis.com/compute/v1/projects/project-id/zones/zone/instanceGroups/instance-group-name/setNamedPorts { "fingerprint": "fingerprint", "namedPorts": [ { "name": "port-name", "port": port-number }, { "name": "port-name", "port": port-number }, .... ] }
Replace the following:
instance-group-name
: The name of the instance group.zone
: The zone of the group.project-id
: The project ID for the project containing the group.port-name
andport-number
: The port name and number represent a mapping from a name you choose to a port number.fingerprint
: This is the fingerprint from the previous step.
What's next
- Create a managed instance group with VMs in a single zone.
- Create a managed instance group with VMs in multiple zones in a region.
- Learn about Cloud Load Balancing.