Sketching new migration system

bolt/dashboards.go

@@ -3,7 +3,6 @@ package bolt
 import (
 	"context"
 	"strconv"
-	"strings"
 
 	"github.com/boltdb/bolt"
 	"github.com/influxdata/chronograf"
@@ -73,45 +72,6 @@ func (d *DashboardsStore) Migrate(ctx context.Context, build chronograf.BuildInf
 		}
 	}
 
-	return d.migrationChangeIntervalToDuration(ctx)
-}
-
-// migrationChangeIntervalToDuration (1.4.2)
-// Before, we supported queries that included `GROUP BY :interval:`
-// After, we only support queries with `GROUP BY time(:interval:)`
-// thereby allowing non_negative_derivative(_____, :interval)
-func (d *DashboardsStore) migrationChangeIntervalToDuration(ctx context.Context) error {
-	versionTimestamp := "20180228182849"
-	complete, err := d.client.BuildStore.IsMigrationComplete(versionTimestamp)
-	if err != nil {
-		return err
-	}
-	if complete {
-		return nil
-	}
-
-	d.client.logger.Info("Running migrationChangeIntervalToDuration (", versionTimestamp, ")")
-
-	boards, err := d.All(ctx)
-	if err != nil {
-		return err
-	}
-
-	for _, board := range boards {
-		for i, cell := range board.Cells {
-			for i, query := range cell.Queries {
-				query.Command = strings.Replace(query.Command, ":interval:", "time(:interval:)", -1)
-				cell.Queries[i] = query
-			}
-
-			board.Cells[i] = cell
-		}
-
-		d.Update(ctx, board)
-	}
-
-	d.client.BuildStore.MarkMigrationAsComplete(versionTimestamp)
-
 	return nil
 }
 

bolt/migrations/base.go

@@ -0,0 +1,59 @@
+package migration
+
+import (
+	"context"
+
+	"github.com/influxdata/chronograf/bolt"
+)
+
+// Migration defines a database state/schema transition
+// 	ID: After the migration is run, this id is stored in the database.
+//      We don't want to run a state transition twice
+//  Up: The forward-transition function. After a version upgrade, a number
+// 			of these will run on database startup in order to bring a user's
+// 			schema in line with struct definitions in the new version.
+//  Down: The backward-transition function. We don't expect these to be
+// 				run on a user's database -- if the user needs to rollback
+// 				to a previous version, it will be easier for them to replace
+// 				their current database with one of their backups. The primary
+// 				purpose of a Down() function is to help contributors move across
+// 				development branches that have different schema definitions.
+type Migration struct {
+	ID   string
+	Up   func(ctx context.Context, client bolt.Client) error
+	Down func(ctx context.Context, client bolt.Client) error
+}
+
+// Migrate runs one migration's Up() function, if it has not already been run
+func (m Migration) Migrate(ctx context.Context, client bolt.Client) error {
+	complete, err := client.BuildStore.IsMigrationComplete(m.ID)
+	if err != nil {
+		return err
+	}
+	if complete {
+		return nil
+	}
+
+	// client.logger.Info("Running migration (", m.ID, ")")
+
+	if err = m.Up(ctx, client); err != nil {
+		return err
+	}
+
+	return client.BuildStore.MarkMigrationAsComplete(m.ID)
+}
+
+// MigrateAll iterates through all known migrations and runs them in order
+func MigrateAll(ctx context.Context, client bolt.Client) error {
+	for _, m := range migrations {
+		if err := m.Migrate(ctx, client); err != nil {
+			return err
+		}
+	}
+
+	return nil
+}
+
+var migrations = []Migration{
+	changeIntervalToDuration,
+}

bolt/migrations/change_interval_to_duration.go

@@ -0,0 +1,44 @@
+package migration
+
+import (
+	"context"
+	"strings"
+
+	"github.com/influxdata/chronograf/bolt"
+)
+
+// changeIntervalToDuration
+// Before, we supported queries that included `GROUP BY :interval:`
+// After, we only support queries with `GROUP BY time(:interval:)`
+// thereby allowing non_negative_derivative(_____, :interval)
+var changeIntervalToDuration = Migration{
+	ID:   "59b0cda4fc7909ff84ee5c4f9cb4b655b6a26620",
+	Up:   up,
+	Down: down,
+}
+
+var up = func(ctx context.Context, client bolt.Client) error {
+	boards, err := client.DashboardsStore.All(ctx)
+	if err != nil {
+		return err
+	}
+
+	for _, board := range boards {
+		for i, cell := range board.Cells {
+			for i, query := range cell.Queries {
+				query.Command = strings.Replace(query.Command, ":interval:", "time(:interval:)", -1)
+				cell.Queries[i] = query
+			}
+
+			board.Cells[i] = cell
+		}
+
+		client.DashboardsStore.Update(ctx, board)
+	}
+
+	return nil
+}
+
+var down = func(ctx context.Context, client bolt.Client) error {
+	return nil
+}