terraform-plugin-framework
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Non-empty plans when migrating existing optional+computed nested Set blocks to Terraform Plugin Framework
Module version
1.4.2
We are currently migrating existing Plugin-SDK based resources to Plugin Framework (Plugin protocol v6). In below resource, we have some optional+computed set block attributes where certain nested attributes if not configured/partially configured by the user in the config, the API/provider will still return those attributes. That response is currently persisted in the state.
In order to migrate these blocks to the Plugin Framework, we have tried using schema.SetNestedBlock but the returned plan after upgrade to the Framework-migrated resource is always non-empty. This will be a breaking change for our users.
What is the recommended non-breaking way to migrate collection attributes such as these?
Relevant provider source code
Terraform Plugin SDK based schema for "replication_specs" block:
"replication_specs": {
Type: schema.TypeSet,
Optional: true,
Computed: true,
Elem: &schema.Resource{
Schema: map[string]*schema.Schema{
"id": {
Type: schema.TypeString,
Optional: true,
Computed: true,
},
"num_shards": {
Type: schema.TypeInt,
Required: true,
},
"regions_config": {
Type: schema.TypeSet,
Optional: true,
Computed: true,
Elem: &schema.Resource{
Schema: map[string]*schema.Schema{
"region_name": {
Type: schema.TypeString,
Required: true,
},
"electable_nodes": {
Type: schema.TypeInt,
Optional: true,
Computed: true,
},
"priority": {
Type: schema.TypeInt,
Optional: true,
Computed: true,
},
"read_only_nodes": {
Type: schema.TypeInt,
Optional: true,
Default: 0,
},
"analytics_nodes": {
Type: schema.TypeInt,
Optional: true,
Default: 0,
},
},
},
},
"zone_name": {
Type: schema.TypeString,
Optional: true,
Default: "ZoneName managed by Terraform",
},
},
},
Set: func(v any) int {
var buf bytes.Buffer
m := v.(map[string]any)
buf.WriteString(fmt.Sprintf("%d", m["num_shards"].(int)))
buf.WriteString(m["zone_name"].(string))
buf.WriteString(fmt.Sprintf("%+v", m["regions_config"].(*schema.Set)))
return advancedcluster.HashCodeString(buf.String())
},
},
Terraform Plugin Framework migrated schema:
func clusterRSReplicationSpecsSchemaBlock() schema.SetNestedBlock {
return schema.SetNestedBlock{
NestedObject: schema.NestedBlockObject{
Attributes: map[string]schema.Attribute{
"id": schema.StringAttribute{
Optional: true,
Computed: true,
},
"num_shards": schema.Int64Attribute{
Required: true,
},
"zone_name": schema.StringAttribute{
Optional: true,
Computed: true,
Default: stringdefault.StaticString("ZoneName managed by Terraform"),
},
},
Blocks: map[string]schema.Block{
"regions_config": schema.SetNestedBlock{
NestedObject: schema.NestedBlockObject{
Attributes: map[string]schema.Attribute{
"analytics_nodes": schema.Int64Attribute{
Optional: true,
Computed: true,
Default: int64default.StaticInt64(0),
},
"electable_nodes": schema.Int64Attribute{
Optional: true,
Computed: true,
},
"priority": schema.Int64Attribute{
Optional: true,
Computed: true,
},
"read_only_nodes": schema.Int64Attribute{
Optional: true,
Computed: true,
Default: int64default.StaticInt64(0),
},
"region_name": schema.StringAttribute{
Required: true,
},
},
},
},
},
},
}
}
Terraform Configuration Files
Use-case 1 (no blocks configured):
main.tf:
resource "mongodbatlas_cluster" "cluster-no-blocks" {
project_id = mongodbatlas_project.project-tf.id
provider_name = "AWS"
name = "tfCluster1"
backing_provider_name = "AWS"
provider_region_name = "US_EAST_1"
provider_instance_size_name = "M10"
auto_scaling_compute_enabled = false
auto_scaling_compute_scale_down_enabled = false
provider_auto_scaling_compute_min_instance_size = "M10"
provider_auto_scaling_compute_max_instance_size = "M20"
}
terraform.tfstate (including only concerned blocks here due to large resource config):
"replication_specs": [
{
"id": "....",
"num_shards": 1,
"regions_config": [
{
"analytics_nodes": 0,
"electable_nodes": 3,
"priority": 7,
"read_only_nodes": 0,
"region_name": "US_EAST_1"
}
],
"zone_name": "Zone 1"
}
],
Use-case 2 (all blocks configured):
main.tf:
resource "mongodbatlas_cluster" "cluster-multi-region-all-blocks" {
project_id = mongodbatlas_project.project-tf.id
name = "cluster-test-multi-region"
num_shards = 1
cloud_backup = true
cluster_type = "REPLICASET"
provider_name = "AWS"
provider_instance_size_name = "M10"
advanced_configuration { # block can be partially configured by user
minimum_enabled_tls_protocol = "TLS1_2"
default_read_concern = "available"
}
bi_connector_config {
enabled = false
read_preference = "secondary"
}
replication_specs {
num_shards = 1
regions_config {
region_name = "US_EAST_1"
electable_nodes = 3
priority = 7
read_only_nodes = 0
}
regions_config {
region_name = "US_EAST_2"
electable_nodes = 2
priority = 6
read_only_nodes = 0
}
regions_config {
region_name = "US_WEST_1"
electable_nodes = 2
priority = 5
read_only_nodes = 2
}
}
}
terraform.tfstate (including only concerned blocks here due to large resource config):
"replication_specs": [
{
"id": "....",
"num_shards": 1,
"regions_config": [
{
"analytics_nodes": 0,
"electable_nodes": 2,
"priority": 5,
"read_only_nodes": 2,
"region_name": "US_WEST_1"
},
{
"analytics_nodes": 0,
"electable_nodes": 2,
"priority": 6,
"read_only_nodes": 0,
"region_name": "US_EAST_2"
},
{
"analytics_nodes": 0,
"electable_nodes": 3,
"priority": 7,
"read_only_nodes": 0,
"region_name": "US_EAST_1"
}
],
"zone_name": "ZoneName managed by Terraform"
}
],
Debug Output
Expected Behavior
After user upgrades to new provider version with the framework-migrated resource, user should not see any planned changes for optional+computed lists/set blocks when running terraform plan
and not receive errors when running terraform apply
.
Actual Behavior
On running terraform plan
below plan was produced by Terraform:
Use-case 1 (no blocks configured):
~ update in-place
Terraform will perform the following actions:
# mongodbatlas_cluster.cluster-no-blocks will be updated in-place
~ resource "mongodbatlas_cluster" "cluster-no-blocks" {
id = "Y2x1c3Rlcl9pZA==:NjU2ODhiMmYzZDI3MWYzZjg2MGI0NjQw-Y2x1c3Rlcl9uYW1l:dGZDbHVzdGVyMQ==-cHJvamVjdF9pZA==:NjRlY2MxNTkyNzVmMjM1OWY0Y2FlODEw-cHJvdmlkZXJfbmFtZQ==:QVdT"
name = "tfCluster1"
~ num_shards = 1 -> (known after apply)
# (34 unchanged attributes hidden)
- replication_specs {
- id = "......." -> null
- num_shards = 1 -> null
- zone_name = "Zone 1" -> null
- regions_config {
- analytics_nodes = 0 -> null
- electable_nodes = 3 -> null
- priority = 7 -> null
- read_only_nodes = 0 -> null
- region_name = "US_EAST_1" -> null
}
}
}
Use-case 2 (all blocks configured):
~ update in-place
Terraform will perform the following actions:
# mongodbatlas_cluster.cluster-multi-region-all-blocks will be updated in-place
~ resource "mongodbatlas_cluster" "cluster-multi-region-all-blocks" {
id = "Y2x1c3Rlcl9pZA==:NjU2ODhlZTgzZDI3MWYzZjg2MGI0ZTY3-Y2x1c3Rlcl9uYW1l:dGYtbXVsdGktcmVnaW9uLWFsbC1ibG9ja3M=-cHJvamVjdF9pZA==:NjRlY2MxNTkyNzVmMjM1OWY0Y2FlODEw-cHJvdmlkZXJfbmFtZQ==:QVdT"
name = "tf-multi-region-all-blocks"
# (32 unchanged attributes hidden)
- replication_specs {
- id = "......." -> null
- num_shards = 1 -> null
- zone_name = "ZoneName managed by Terraform" -> null
- regions_config {
- analytics_nodes = 0 -> null
- electable_nodes = 2 -> null
- priority = 5 -> null
- read_only_nodes = 2 -> null
- region_name = "US_WEST_1" -> null
}
- regions_config {
- analytics_nodes = 0 -> null
- electable_nodes = 2 -> null
- priority = 6 -> null
- read_only_nodes = 0 -> null
- region_name = "US_EAST_2" -> null
}
- regions_config {
- analytics_nodes = 0 -> null
- electable_nodes = 3 -> null
- priority = 7 -> null
- read_only_nodes = 0 -> null
- region_name = "US_EAST_1" -> null
}
}
+ replication_specs {
+ num_shards = 1
+ zone_name = "ZoneName managed by Terraform"
+ regions_config {
+ analytics_nodes = 0
+ electable_nodes = 2
+ priority = 5
+ read_only_nodes = 2
+ region_name = "US_WEST_1"
}
+ regions_config {
+ analytics_nodes = 0
+ electable_nodes = 2
+ priority = 6
+ read_only_nodes = 0
+ region_name = "US_EAST_2"
}
+ regions_config {
+ analytics_nodes = 0
+ electable_nodes = 3
+ priority = 7
+ read_only_nodes = 0
+ region_name = "US_EAST_1"
}
}
Steps to Reproduce
- run
terraform init
for provider v.X (contains-Plugin-SDK-based-resource-implementation) for above resource - run
terraform plan
- run
terraform apply
- run
terraform plan
again -> plan returnsNo changes.
- update provider version to v.Y (contains-Plugin-Framework-based-resource-implementation) for above resource, run
terraform init --upgrade
- run
terraform plan
-> Plan is not empty
References
- Related issue for list blocks migration - https://github.com/hashicorp/terraform-plugin-framework/issues/883
- replication_specs Plugin-SDK schema (note Set function)