plugin migration order specified in config

cmd/compose.go

@@ -18,6 +18,7 @@ package cmd
 import (
 	"errors"
 	"fmt"
+	"strconv"
 
 	log "github.com/sirupsen/logrus"
 	"github.com/spf13/cobra"
@@ -132,32 +133,41 @@ func prepConfig() {
 	transformers := make(map[string]config.Transformer)
 	for _, name := range names {
 		transformer := viper.GetStringMapString("exporter." + name)
-		p, ok := transformer["path"]
-		if !ok || p == "" {
-			log.Fatal(fmt.Sprintf("%s transformer config is missing `path` value", name))
+		p, pOK := transformer["path"]
+		if !pOK || p == "" {
+			log.Fatal(name, "transformer config is missing `path` value")
 		}
-		r, ok := transformer["repository"]
-		if !ok || r == "" {
-			log.Fatal(fmt.Sprintf("%s transformer config is missing `repository` value", name))
+		r, rOK := transformer["repository"]
+		if !rOK || r == "" {
+			log.Fatal(name, "transformer config is missing `repository` value")
 		}
-		m, ok := transformer["migrations"]
-		if !ok || m == "" {
-			log.Fatal(fmt.Sprintf("%s transformer config is missing `migrations` value", name))
+		m, mOK := transformer["migrations"]
+		if !mOK || m == "" {
+			log.Fatal(name, "transformer config is missing `migrations` value")
 		}
-		t, ok := transformer["type"]
-		if !ok {
-			log.Fatal(fmt.Sprintf("%s transformer config is missing `type` value", name))
+		mr, mrOK := transformer["rank"]
+		if !mrOK || mr == "" {
+			log.Fatal(name, "transformer config is missing `rank` value")
+		}
+		t, tOK := transformer["type"]
+		if !tOK {
+			log.Fatal(name, "transformer config is missing `type` value")
 		}
 		transformerType := config.GetTransformerType(t)
 		if transformerType == config.UnknownTransformerType {
 			log.Fatal(errors.New(`unknown transformer type in exporter config accepted types are "eth_event", "eth_storage"`))
 		}
+		rank, err := strconv.Atoi(mr)
+		if err != nil {
+			log.Fatal(name, "migration `rank` can't be converted to an integer")
+		}
 
 		transformers[name] = config.Transformer{
 			Path:           p,
 			Type:           transformerType,
 			RepositoryPath: r,
 			MigrationPath:  m,
+			MigrationRank:  rank,
 		}
 	}
 

pkg/config/plugin.go

@@ -17,6 +17,8 @@
 package config
 
 import (
+	"errors"
+	"fmt"
 	"path/filepath"
 	"strings"
 
@@ -35,6 +37,7 @@ type Transformer struct {
 	Path           string
 	Type           TransformerType
 	MigrationPath  string
+	MigrationRank  int
 	RepositoryPath string
 }
 
@@ -51,10 +54,10 @@ func (c *Plugin) GetPluginPaths() (string, string, error) {
 	return goFile, soFile, nil
 }
 
-// Removes duplicate migration paths before returning them
-func (c *Plugin) GetMigrationsPaths() (map[string]bool, error) {
-	paths := make(map[string]bool)
-	for _, transformer := range c.Transformers {
+// Removes duplicate migration paths and returns them in ranked order
+func (c *Plugin) GetMigrationsPaths() ([]string, error) {
+	paths := make(map[int]string)
+	for name, transformer := range c.Transformers {
 		repo := transformer.RepositoryPath
 		mig := transformer.MigrationPath
 		path := filepath.Join("$GOPATH/src", c.Home, "vendor", repo, mig)
@@ -62,10 +65,23 @@ func (c *Plugin) GetMigrationsPaths() (map[string]bool, error) {
 		if err != nil {
 			return nil, err
 		}
-		paths[cleanPath] = true
+		// If there is a different path with the same rank then we have a conflict
+		_, ok := paths[transformer.MigrationRank]
+		if ok {
+			conflictingPath := paths[transformer.MigrationRank]
+			if conflictingPath != cleanPath {
+				return nil, errors.New(fmt.Sprintf("transformer %s has the same migration rank (%d) as another transformer", name, transformer.MigrationRank))
+			}
+		}
+		paths[transformer.MigrationRank] = cleanPath
 	}
 
-	return paths, nil
+	sortedPaths := make([]string, len(paths))
+	for rank, path := range paths {
+		sortedPaths[rank] = path
+	}
+
+	return sortedPaths, nil
 }
 
 // Removes duplicate repo paths before returning them

pkg/plugin/manager/manager.go

@@ -105,9 +105,9 @@ func (m *manager) setupMigrationEnv() error {
 }
 
 // Create copies of db migrations from vendored libs
-func (m *manager) createMigrationCopies(paths map[string]bool) error {
+func (m *manager) createMigrationCopies(paths []string) error {
 	// Iterate through migration paths to find migration directory
-	for path := range paths {
+	for _, path := range paths {
 		dir, err := ioutil.ReadDir(path)
 		if err != nil {
 			return err