Add promote command.

internal/cmd/branch/branch.go

@@ -30,6 +30,7 @@ func BranchCmd(ch *cmdutil.Helper) *cobra.Command {
 	cmd.AddCommand(DiffCmd(ch))
 	cmd.AddCommand(SchemaCmd(ch))
 	cmd.AddCommand(RefreshSchemaCmd(ch))
+	cmd.AddCommand(PromoteCmd(ch))
 
 	return cmd
 }

internal/cmd/branch/promote.go

@@ -0,0 +1,98 @@
+package branch
+
+import (
+	"fmt"
+
+	"github.com/planetscale/cli/internal/cmdutil"
+	"github.com/planetscale/cli/internal/printer"
+	"github.com/spf13/cobra"
+
+	ps "github.com/planetscale/planetscale-go/planetscale"
+)
+
+func PromoteCmd(ch *cmdutil.Helper) *cobra.Command {
+	promoteReq := &ps.PromoteBranchRequest{}
+
+	cmd := &cobra.Command{
+		Use:     "promote <database> <branch> [options]",
+		Short:   "Promote a new branch from a database",
+		Args:    cmdutil.RequiredArgs("source-database", "branch"),
+		Aliases: []string{"b"},
+		ValidArgsFunction: func(cmd *cobra.Command, args []string, toComplete string) ([]string, cobra.ShellCompDirective) {
+			if len(args) != 0 {
+				return nil, cobra.ShellCompDirectiveNoFileComp
+			}
+
+			client, err := ch.Client()
+			if err != nil {
+				return nil, cobra.ShellCompDirectiveNoFileComp
+			}
+
+			org := ch.Config.Organization // --org flag
+			if org == "" {
+				cfg, err := ch.ConfigFS.DefaultConfig()
+				if err != nil {
+					return nil, cobra.ShellCompDirectiveNoFileComp
+				}
+
+				org = cfg.Organization
+			}
+
+			databases, err := client.Databases.List(cmd.Context(), &ps.ListDatabasesRequest{
+				Organization: org,
+			})
+			if err != nil {
+				return nil, cobra.ShellCompDirectiveNoFileComp
+			}
+
+			candidates := make([]string, 0, len(databases))
+			for _, db := range databases {
+				candidates = append(candidates, db.Name)
+			}
+
+			return candidates, cobra.ShellCompDirectiveNoFileComp
+		},
+		RunE: func(cmd *cobra.Command, args []string) error {
+			source := args[0]
+			branch := args[1]
+
+			// Simplest case, the names are equivalent
+			if source == branch {
+				return fmt.Errorf("a branch named '%s' already exists", branch)
+			}
+
+			promoteReq.Database = source
+			promoteReq.Organization = ch.Config.Organization
+			promoteReq.Branch = branch
+
+			client, err := ch.Client()
+			if err != nil {
+				return err
+			}
+
+			end := ch.Printer.PrintProgress(fmt.Sprintf("Creating branch from %s...", printer.BoldBlue(source)))
+			defer end()
+			dbBranch, err := client.DatabaseBranches.Promote(cmd.Context(), promoteReq)
+			if err != nil {
+				switch cmdutil.ErrCode(err) {
+				case ps.ErrNotFound:
+					return fmt.Errorf("source database %s does not exist in organization %s",
+						printer.BoldBlue(source), printer.BoldBlue(ch.Config.Organization))
+				default:
+					return cmdutil.HandleError(err)
+				}
+			}
+
+			end()
+
+			if ch.Printer.Format() == printer.Human {
+				ch.Printer.Printf("Branch %s was successfully promoted.\n", printer.BoldBlue(dbBranch.Name))
+				return nil
+			}
+
+			return ch.Printer.PrintResource(toDatabaseBranch(dbBranch))
+		},
+	}
+
+	return cmd
+}