prune: Make it work with old TF versions using 'depends_on'

We fixed this issue on the 'generate' but not on the 'prune' so we imported the fix we did

CHANGELOG.md

@@ -1,5 +1,9 @@
 ## [Unreleased]
 
+### Fixed
+- Prune was not working with old TF versions because of the `depends_on`
+  ([Issue #144](https://github.com/cycloidio/inframap/pull/144))
+
 ## [0.6.6] _2021-06-10_
 
 ### Changed

generate/state.go

@@ -24,7 +24,7 @@ func FromState(tfstate json.RawMessage, opt Options) (*graph.Graph, map[string]i
 	// replace from '"depends_on"' to '"dependencies"'
 	hasDependsOn := bytes.Contains(tfstate, []byte("\"depends_on\""))
 	tfstate = bytes.ReplaceAll(tfstate, []byte("\"depends_on\""), []byte("\"dependencies\""))
-	err := validateTFStateVersion(tfstate)
+	err := ValidateTFStateVersion(tfstate)
 	if err != nil {
 		return nil, nil, fmt.Errorf("error while validating TFStateVersion: %w", err)
 	}
@@ -273,9 +273,9 @@ func migrateVersions(src []byte, f *statefile.File) error {
 	return nil
 }
 
-// validateTFStateVersion validates that the version is the
+// ValidateTFStateVersion validates that the version is the
 // one we support which is only 3 and 4
-func validateTFStateVersion(b []byte) error {
+func ValidateTFStateVersion(b []byte) error {
 	v, err := tfStateVersion(b)
 	if err != nil {
 		return fmt.Errorf("could not read version: %w", err)

prune/prune.go

@@ -10,6 +10,7 @@ import (
 
 	"github.com/chr4/pwgen"
 	"github.com/cycloidio/inframap/errcode"
+	"github.com/cycloidio/inframap/generate"
 	"github.com/cycloidio/inframap/provider/factory"
 	"github.com/hashicorp/terraform/addrs"
 	"github.com/hashicorp/terraform/states/statefile"
@@ -23,7 +24,16 @@ var reARN = regexp.MustCompile("^arn:*")
 // the resource canonicals will also be changed, for exmple 'aws_lb.front' will be changed to
 // a random name like 'aws_lb.XptaK'
 func Prune(tfstate json.RawMessage, replaceCanonicals bool) (json.RawMessage, error) {
+	// Since TF 0.13 'depends_on' has been dropped, so we do a manual
+	// replace from '"depends_on"' to '"dependencies"'
+	tfstate = bytes.ReplaceAll(tfstate, []byte("\"depends_on\""), []byte("\"dependencies\""))
+	err := generate.ValidateTFStateVersion(tfstate)
+	if err != nil {
+		return nil, fmt.Errorf("error while validating TFStateVersion: %w", err)
+	}
+
 	buf := bytes.NewBuffer(tfstate)
+
 	file, err := statefile.Read(buf)
 	if err != nil {
 		return nil, fmt.Errorf("error while reading TFState: %w", err)