ignore drift in rds.Cluster and rds.Instance due to engine_version diff arising out of automanaged upgrades

config/rds/config.go

@@ -8,15 +8,17 @@ import (
 	"fmt"
 
 	"github.com/hashicorp/terraform-plugin-sdk/v2/helper/schema"
+	"github.com/hashicorp/terraform-plugin-sdk/v2/terraform"
 
 	"github.com/crossplane/upjet/pkg/config"
 	"github.com/crossplane/upjet/pkg/types/comments"
 
 	"github.com/upbound/provider-aws/config/common"
+	"github.com/upbound/provider-aws/config/rds/utils"
 )
 
 // Configure adds configurations for the rds group.
-func Configure(p *config.Provider) {
+func Configure(p *config.Provider) { //nolint:gocyclo
 	p.AddResourceConfigurator("aws_rds_cluster", func(r *config.Resource) {
 		// Mutually exclusive with aws_rds_cluster_role_association
 		config.MoveToStatus(r.TerraformResource, "iam_roles")
@@ -80,6 +82,20 @@ func Configure(p *config.Provider) {
 			"master DB user. If you set autoGeneratePassword to true, the Secret" +
 			" referenced here will be created or updated with generated password" +
 			" if it does not already contain one."
+		r.TerraformCustomDiff = func(diff *terraform.InstanceDiff, _ *terraform.InstanceState, _ *terraform.ResourceConfig) (*terraform.InstanceDiff, error) {
+			if diff == nil || diff.Destroy {
+				return diff, nil
+			}
+			// Ignore the engine version diff, if the desired spec version is lower than the external's actual version.
+			// Downgrades are not allowed by AWS RDS.
+			if evDiff, ok := diff.Attributes["engine_version"]; ok && evDiff.Old != "" && evDiff.New != "" {
+				c := utils.CompareEngineVersions(evDiff.New, evDiff.Old)
+				if c <= 0 {
+					delete(diff.Attributes, "engine_version")
+				}
+			}
+			return diff, nil
+		}
 	})
 
 	p.AddResourceConfigurator("aws_rds_cluster_instance", func(r *config.Resource) {
@@ -167,6 +183,20 @@ func Configure(p *config.Provider) {
 			" if it does not already contain one."
 		r.MetaResource.ArgumentDocs["engine"] = "- (Required unless a `snapshotIdentifier` or `replicateSourceDb` is provided) The database engine to use. For supported values, see the Engine parameter in [API action CreateDBInstance](https://docs.aws.amazon.com/AmazonRDS/latest/APIReference/API_CreateDBInstance.html). Note that for Amazon Aurora instances the engine must match the [DB Cluster](https://marketplace.upbound.io/providers/upbound/provider-aws/latest/resources/rds.aws.upbound.io/Cluster/v1beta1)'s engine'. For information on the difference between the available Aurora MySQL engines see Comparison in the [Amazon RDS Release Notes](https://docs.aws.amazon.com/AmazonRDS/latest/AuroraMySQLReleaseNotes/Welcome.html)."
 		r.MetaResource.ArgumentDocs["engine_version"] = "- (Optional) The engine version to use. If `autoMinorVersionUpgrade` is enabled, you can provide a prefix of the version such as 5.7 (for 5.7.10). The actual engine version used is returned in the attribute `status.atProvider.engineVersionActual`. For supported values, see the EngineVersion parameter in [API action CreateDBInstance](https://docs.aws.amazon.com/AmazonRDS/latest/APIReference/API_CreateDBInstance.html). Note that for Amazon Aurora instances the engine version must match the [DB Cluster](https://marketplace.upbound.io/providers/upbound/provider-aws/latest/resources/rds.aws.upbound.io/Cluster/v1beta1)'s engine version'."
+		r.TerraformCustomDiff = func(diff *terraform.InstanceDiff, _ *terraform.InstanceState, _ *terraform.ResourceConfig) (*terraform.InstanceDiff, error) {
+			if diff == nil || diff.Destroy {
+				return diff, nil
+			}
+			// Ignore the engine version diff, if the desired spec version is lower than the external's actual version.
+			// Downgrades are not allowed by AWS RDS.
+			if evDiff, ok := diff.Attributes["engine_version"]; ok && evDiff.Old != "" && evDiff.New != "" {
+				c := utils.CompareEngineVersions(evDiff.New, evDiff.Old)
+				if c <= 0 {
+					delete(diff.Attributes, "engine_version")
+				}
+			}
+			return diff, nil
+		}
 	})
 
 	p.AddResourceConfigurator("aws_db_proxy", func(r *config.Resource) {

config/rds/utils/engine_version.go

@@ -0,0 +1,89 @@
+// SPDX-FileCopyrightText: 2024 The Crossplane Authors <https://crossplane.io>
+//
+// SPDX-License-Identifier: CC0-1.0
+
+package utils
+
+import (
+	"strconv"
+	"strings"
+)
+
+// EngineVersion represents an AWS RDS engine version.
+type EngineVersion []any
+
+// ParseEngineVersion from a raw string.
+func ParseEngineVersion(raw string) EngineVersion {
+	split := strings.Split(raw, ".")
+
+	v := make(EngineVersion, len(split))
+	for i, s := range split {
+		d, err := strconv.Atoi(s)
+		if err != nil {
+			v[i] = s
+		} else {
+			v[i] = d
+		}
+	}
+	return v
+}
+
+const (
+	compareIsHigher = 1
+	compareIsEqual  = 0
+	compareIsLower  = -1
+)
+
+// Compare returns a positive value if v is represents a higher version number
+// than other. A negative value is returned if other is higher than v.
+// It returns 0 if both are considered equal.
+func (v EngineVersion) Compare(other EngineVersion) int {
+	if other == nil {
+		return compareIsHigher
+	}
+
+	for i := 0; i < len(v); i++ {
+		a := v.get(i)
+		b := other.get(i)
+		c := compareVersionComponents(a, b)
+		if c != 0 {
+			return c
+		}
+	}
+	return compareIsEqual
+}
+
+func compareVersionComponents(a, b any) int {
+	if a == b {
+		return compareIsEqual
+	}
+	if b == nil {
+		return compareIsHigher
+	}
+	aI, aIsInt := a.(int)
+	bI, bIsInt := b.(int)
+	if aIsInt {
+		if bIsInt {
+			return aI - bI
+		}
+		return compareIsHigher
+	}
+	if bIsInt {
+		return compareIsLower
+	}
+	return compareIsEqual // We cannot decide if both are strings.
+}
+
+func (v EngineVersion) get(i int) any {
+	if i >= 0 && i < len(v) {
+		return v[i]
+	}
+	return nil
+}
+
+// CompareEngineVersions is a shortcut to compare two engine versions.
+func CompareEngineVersions(a, b string) int {
+	av := ParseEngineVersion(a)
+	bv := ParseEngineVersion(b)
+	return av.Compare(bv)
+}

config/rds/utils/engine_version_test.go

@@ -0,0 +1,186 @@
+// SPDX-FileCopyrightText: 2024 The Crossplane Authors <https://crossplane.io>
+//
+// SPDX-License-Identifier: Apache-2.0
+
+package utils
+
+import (
+	"testing"
+
+	"github.com/google/go-cmp/cmp"
+)
+
+func TestEngineVersionIsHigherOrEqual(t *testing.T) {
+	type args struct {
+		spec    string
+		current string
+	}
+
+	type want struct {
+		result int
+	}
+
+	cases := map[string]struct {
+		args
+		want
+	}{
+		"AuroraMySQLIsEqual": {
+			args: args{
+				spec:    "5",
+				current: "5.7.mysql_aurora.2.07.0",
+			},
+			want: want{
+				result: 0,
+			},
+		},
+		"AuroraMySQLIsEqual2": {
+			args: args{
+				spec:    "5.7",
+				current: "5.7.mysql_aurora.2.07.0",
+			},
+			want: want{
+				result: 0,
+			},
+		},
+		"AuroraMySQLIsHigher": {
+			args: args{
+				spec:    "8",
+				current: "5.7.mysql_aurora.2.07.0",
+			},
+			want: want{
+				result: 1,
+			},
+		},
+		"AuroraPostgresIsEqual": {
+			args: args{
+				spec:    "14",
+				current: "14.4",
+			},
+			want: want{
+				result: 0,
+			},
+		},
+		"AuroraPostgresIsLower": {
+			args: args{
+				spec:    "14",
+				current: "15.2",
+			},
+			want: want{
+				result: -1,
+			},
+		},
+		"MariaDBIsEqual": {
+			args: args{
+				spec:    "10",
+				current: "10.3.35",
+			},
+			want: want{
+				result: 0,
+			},
+		},
+		"MariaDBNotIsLower": {
+			args: args{
+				spec:    "10",
+				current: "11.0",
+			},
+			want: want{
+				result: -1,
+			},
+		},
+		"MySQLIsEqual": {
+			args: args{
+				spec:    "5.7",
+				current: "5.7.38",
+			},
+			want: want{
+				result: 0,
+			},
+		},
+		"MySQLIsHigher": {
+			args: args{
+				spec:    "8",
+				current: "5.7.38",
+			},
+			want: want{
+				result: 1,
+			},
+		},
+		"OracleIsEqual": {
+			args: args{
+				spec:    "19",
+				current: "19.0.0.0.ru-2023-01.rur-2023-01.r1",
+			},
+			want: want{
+				result: 0,
+			},
+		},
+		"OracleIsHigher": {
+			args: args{
+				spec:    "20",
+				current: "19.0.0.0.ru-2023-01.rur-2023-01.r1",
+			},
+			want: want{
+				result: 1,
+			},
+		},
+		"PostgresIsEqual": {
+			args: args{
+				spec:    "10",
+				current: "10.17",
+			},
+			want: want{
+				result: 0,
+			},
+		},
+		"PostgresIsHigher": {
+			args: args{
+				spec:    "14",
+				current: "10.17",
+			},
+			want: want{
+				result: 1,
+			},
+		},
+		"SQLServerIsEqual": {
+			args: args{
+				spec:    "12",
+				current: "12.00.6293.0.v1",
+			},
+			want: want{
+				result: 0,
+			},
+		},
+		"SQLServerIsHigher": {
+			args: args{
+				spec:    "14",
+				current: "12.00.6293.0.v1",
+			},
+			want: want{
+				result: 1,
+			},
+		},
+	}
+
+	for name, tc := range cases {
+		t.Run(name, func(t *testing.T) {
+			specV := ParseEngineVersion(tc.args.spec)
+			curV := ParseEngineVersion(tc.args.current)
+
+			res := specV.Compare(curV)
+			resSign := sign(res)
+			if diff := cmp.Diff(tc.want.result, resSign); diff != "" {
+				t.Errorf("r: -want, +got:\n%q\n%q\n%s", tc.args.spec, tc.args.current, diff)
+			}
+		})
+	}
+}
+
+func sign(x int) int {
+	if x < 0 {
+		return -1
+	}
+	if x > 0 {
+		return 1
+	}
+	return 0
+}