add alias+datastream rollover, and auto rollover on index tpl change (#40)

fixes #37

pkg/es/rollover.go

@@ -0,0 +1,65 @@
+/*
+Copyright © 2026 Thomas von Dein
+
+This program is free software: you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation, either version 3 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with this program. If not, see <http://www.gnu.org/licenses/>.
+*/
+package es
+
+import (
+	"context"
+
+	"codeberg.org/scip/esctl/pkg/cfg"
+	"github.com/elastic/go-elasticsearch/v9/typedapi/esdsl"
+	"github.com/elastic/go-elasticsearch/v9/typedapi/indices/rollover"
+	"github.com/elastic/go-elasticsearch/v9/typedapi/types"
+)
+
+func RolloverConditions(conf *cfg.Config) types.RolloverConditionsVariant {
+	cond := esdsl.NewRolloverConditions()
+
+	if conf.MaxAge != "" {
+		cond.MaxAge(esdsl.NewDuration().String(conf.MaxAge))
+	}
+	if conf.MaxDocs > 0 {
+		cond.MaxDocs(int64(conf.MaxDocs))
+	}
+	if conf.MaxShardSize > 0 {
+		bs := esdsl.NewByteSize()
+		bs.Int64(int64(conf.MaxShardSize))
+		cond.MaxPrimaryShardSize(bs)
+	}
+	if conf.MaxShardDocs > 0 {
+		cond.MaxPrimaryShardDocs(int64(conf.MaxShardDocs))
+	}
+
+	return cond
+}
+
+func RolloverAlias(conf *cfg.Config, alias string) (*rollover.Response, error) {
+	roll := conf.DefaultCluster.ES.Indices.Rollover(alias)
+
+	if conf.Wait {
+		roll.WaitForActiveShards("all")
+	}
+
+	if conf.DryRun {
+		roll.DryRun(true)
+	}
+
+	cond := RolloverConditions(conf)
+
+	roll.Conditions(cond)
+
+	return roll.Do(context.Background())
+}