Added support for Stateful Managed Instance Groups (#367)
* First iteration updates * All tests passing * Updated README and var descriptions * Updated README * Updated example README * Consolidated stateful vars * consolidated stateful vars * Updated README * Requested changes to try * Fixed README examples and try Co-authored-by: Ludovico Magnocavallo <ludomagno@google.com>
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Stenio Ferreira
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# GCE Managed Instance Group module
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This module allows creating a managed instance group supporting one or more application versions via instance templates. A health check and an autoscaler can also be optionally created.
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This module allows creating a managed instance group supporting one or more application versions via instance templates. Optionally, a health check and an autoscaler can be created, and the managed instance group can be configured to be stateful.
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This module can be coupled with the [`compute-vm`](../compute-vm) module which can manage instance templates, and the [`net-ilb`](../net-ilb) module to assign the MIG to a backend wired to an Internal Load Balancer. The first use case is shown in the examples below.
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This module can be coupled with the [`compute-vm`](../compute-vm) module which can manage instance templates, and the [`net-ilb`](../net-ilb) module to assign the MIG to a backend wired to an Internal Load Balancer. The first use case is shown in the examples below.
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Stateful disks can be created directly, as shown in the last example below.
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## Examples
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@@ -266,6 +268,182 @@ module "nginx-mig" {
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# tftest:modules=2:resources=2
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```
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### Stateful MIGs - MIG Config
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Stateful MIGs have some limitations documented [here](https://cloud.google.com/compute/docs/instance-groups/configuring-stateful-migs#limitations). Enforcement of these requirements is the responsibility of users of this module.
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You can configure a disk defined in the instance template to be stateful for all instances in the MIG by configuring in the MIG's stateful policy, using the `stateful_disk_mig` variable. Alternatively, you can also configure stateful persistent disks individually per instance of the MIG by setting the `stateful_disk_instance` variable. A discussion on these scenarios can be found in the [docs](https://cloud.google.com/compute/docs/instance-groups/configuring-stateful-disks-in-migs).
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An example using only the configuration at the MIG level can be seen below.
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Note that when referencing the stateful disk, you use `device_name` and not `disk_name`.
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```hcl
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module "cos-nginx" {
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source = "./modules/cloud-config-container/nginx"
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}
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module "nginx-template" {
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source = "./modules/compute-vm"
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project_id = var.project_id
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name = "nginx-template"
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zone = "europe-west1-b"
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tags = ["http-server", "ssh"]
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network_interfaces = [{
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network = var.vpc.self_link
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subnetwork = var.subnet.self_link
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nat = false
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addresses = null
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}]
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boot_disk = {
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image = "projects/cos-cloud/global/images/family/cos-stable"
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type = "pd-ssd"
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size = 10
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}
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attached_disks = [{
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name = "repd-1"
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size = null
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source_type = "attach"
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source = "regions/${var.region}/disks/repd-test-1"
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options = {
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mode = "READ_ONLY"
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replica_zone = "${var.region}-c"
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type = "PERSISTENT"
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}
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}]
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create_template = true
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metadata = {
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user-data = module.cos-nginx.cloud_config
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}
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}
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module "nginx-mig" {
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source = "./modules/compute-mig"
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project_id = "my-project"
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location = "europe-west1-b"
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name = "mig-test"
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target_size = 3
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default_version = {
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instance_template = module.nginx-template.template.self_link
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name = "default"
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}
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autoscaler_config = {
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max_replicas = 3
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min_replicas = 1
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cooldown_period = 30
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cpu_utilization_target = 0.65
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load_balancing_utilization_target = null
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metric = null
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}
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stateful_config = {
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per_instance_config = {},
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mig_config = {
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stateful_disks = {
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persistent-disk-1 = {
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delete_rule = "NEVER"
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}
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}
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}
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}
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}
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# tftest:modules=2:resources=3
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```
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### Stateful MIGs - Instance Config
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Here is an example defining the stateful config at the instance level.
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Note that you will need to know the instance name in order to use this configuration.
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```hcl
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module "cos-nginx" {
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source = "./modules/cloud-config-container/nginx"
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}
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module "nginx-template" {
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source = "./modules/compute-vm"
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project_id = var.project_id
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name = "nginx-template"
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zone = "europe-west1-b"
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tags = ["http-server", "ssh"]
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network_interfaces = [{
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network = var.vpc.self_link
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subnetwork = var.subnet.self_link
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nat = false
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addresses = null
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}]
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boot_disk = {
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image = "projects/cos-cloud/global/images/family/cos-stable"
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type = "pd-ssd"
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size = 10
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}
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attached_disks = [{
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name = "repd-1"
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size = null
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source_type = "attach"
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source = "regions/${var.region}/disks/repd-test-1"
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options = {
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mode = "READ_ONLY"
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replica_zone = "${var.region}-c"
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type = "PERSISTENT"
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}
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}]
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create_template = true
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metadata = {
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user-data = module.cos-nginx.cloud_config
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}
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}
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module "nginx-mig" {
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source = "./modules/compute-mig"
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project_id = "my-project"
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location = "europe-west1-b"
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name = "mig-test"
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target_size = 3
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default_version = {
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instance_template = module.nginx-template.template.self_link
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name = "default"
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}
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autoscaler_config = {
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max_replicas = 3
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min_replicas = 1
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cooldown_period = 30
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cpu_utilization_target = 0.65
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load_balancing_utilization_target = null
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metric = null
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}
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stateful_config = {
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per_instance_config = {
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# note that this needs to be the name of an existing instance within the Managed Instance Group
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instance-1 = {
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stateful_disks = {
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persistent-disk-1 = {
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source = "test-disk",
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mode = "READ_ONLY",
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delete_rule= "NEVER",
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},
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},
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metadata = {
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foo = "bar"
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},
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update_config = {
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minimal_action = "NONE",
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most_disruptive_allowed_action = "REPLACE",
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remove_instance_state_on_destroy = false,
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},
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},
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},
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mig_config = {
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stateful_disks = {
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}
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}
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}
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}
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# tftest:modules=2:resources=4
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```
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<!-- BEGIN TFDOC -->
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## Variables
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@@ -280,6 +458,7 @@ module "nginx-mig" {
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| *health_check_config* | Optional auto-created health check configuration, use the output self-link to set it in the auto healing policy. Refer to examples for usage. | <code title="object({ type = string # http https tcp ssl http2 check = map(any) # actual health check block attributes config = map(number) # interval, thresholds, timeout logging = bool })">object({...})</code> | | <code title="">null</code> |
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| *named_ports* | Named ports. | <code title="map(number)">map(number)</code> | | <code title="">null</code> |
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| *regional* | Use regional instance group. When set, `location` should be set to the region. | <code title="">bool</code> | | <code title="">false</code> |
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| *stateful_config* | Stateful configuration can be done by individual instances or for all instances in the MIG. They key in per_instance_config is the name of the specific instance. The key of the stateful_disks is the 'device_name' field of the resource. Please note that device_name is defined at the OS mount level, unlike the disk name. | <code title="object({ per_instance_config = map(object({ stateful_disks = map(object({ source = string mode = string # READ_WRITE | READ_ONLY delete_rule = string # NEVER | ON_PERMANENT_INSTANCE_DELETION })) metadata = map(string) update_config = object({ minimal_action = string # NONE | REPLACE | RESTART | REFRESH most_disruptive_allowed_action = string # REPLACE | RESTART | REFRESH | NONE remove_instance_state_on_destroy = bool }) })) mig_config = object({ stateful_disks = map(object({ delete_rule = string # NEVER | ON_PERMANENT_INSTANCE_DELETION })) }) })">object({...})</code> | | <code title="">null</code> |
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| *target_pools* | Optional list of URLs for target pools to which new instances in the group are added. | <code title="list(string)">list(string)</code> | | <code title="">[]</code> |
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| *target_size* | Group target size, leave null when using an autoscaler. | <code title="">number</code> | | <code title="">null</code> |
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| *update_policy* | Update policy. Type can be 'OPPORTUNISTIC' or 'PROACTIVE', action 'REPLACE' or 'restart', surge type 'fixed' or 'percent'. | <code title="object({ type = string # OPPORTUNISTIC | PROACTIVE minimal_action = string # REPLACE | RESTART min_ready_sec = number max_surge_type = string # fixed | percent max_surge = number max_unavailable_type = string max_unavailable = number })">object({...})</code> | | <code title="">null</code> |
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@@ -297,4 +476,4 @@ module "nginx-mig" {
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## TODO
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- [ ] add support for instance groups
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- [✓] add support for instance groups
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