feat: integrate azure storage handling in migration pipeline

Stream transformer output to an Azure blob container when a job declares ToStorage, with per-job prefix and credential configuration.

internal/app/etl/loaders/main.go

@@ -15,31 +15,21 @@ import (
 	"github.com/jackc/pgx/v5/pgconn"
 )
 
-type PostgresLoader struct {
+type GenericLoader struct {
 	db dbwrapper.DbWrapper
 }
 
-func NewPostgresLoader(db dbwrapper.DbWrapper) etl.Loader {
-	return &PostgresLoader{db: db}
+func NewGenericLoader(db dbwrapper.DbWrapper) etl.Loader {
+	return &GenericLoader{db: db}
 }
 
-func mapSlice[T any, V any](input []T, mapper func(T) V) []V {
-	result := make([]V, len(input))
-
-	for i, v := range input {
-		result[i] = mapper(v)
-	}
-
-	return result
-}
-
-func (postgresLd *PostgresLoader) ProcessBatch(
+func (gl *GenericLoader) ProcessBatch(
 	ctx context.Context,
 	tableInfo config.TargetTableInfo,
 	colNames []string,
 	batch models.Batch,
 ) (int, error) {
-	_, err := postgresLd.db.SaveMassive(
+	_, err := gl.db.SaveMassive(
 		ctx,
 		tableInfo.Schema,
 		tableInfo.Table,
@@ -65,7 +55,7 @@ func (postgresLd *PostgresLoader) ProcessBatch(
 	return len(batch.Rows), nil
 }
 
-func (postgresLd *PostgresLoader) Exec(
+func (gl *GenericLoader) Exec(
 	ctx context.Context,
 	tableInfo config.TargetTableInfo,
 	columns []models.ColumnType,
@@ -92,7 +82,7 @@ func (postgresLd *PostgresLoader) Exec(
 				return
 			}
 
-			processedRows, err := postgresLd.ProcessBatch(ctx, tableInfo, colNames, batch)
+			processedRows, err := gl.ProcessBatch(ctx, tableInfo, colNames, batch)
 
 			if err != nil {
 				var ldError *custom_errors.LoaderError

internal/app/etl/loaders/types.go

@@ -1 +0,0 @@
-package loaders

internal/app/etl/loaders/utils.go

@@ -0,0 +1,11 @@
+package loaders
+
+func mapSlice[T any, V any](input []T, mapper func(T) V) []V {
+	result := make([]V, len(input))
+
+	for i, v := range input {
+		result[i] = mapper(v)
+	}
+
+	return result
+}