2 files changed, 161 insertions, 0 deletions

diff --git a/modules/indexer/internal/elasticsearch/indexer.go b/modules/indexer/internal/elasticsearch/indexer.go
new file mode 100644
index 0000000..395eea3
--- /dev/null
+++ b/modules/indexer/internal/elasticsearch/indexer.go
@@ -0,0 +1,93 @@
+// Copyright 2023 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package elasticsearch
+
+import (
+	"context"
+	"fmt"
+
+	"code.gitea.io/gitea/modules/indexer/internal"
+
+	"github.com/olivere/elastic/v7"
+)
+
+var _ internal.Indexer = &Indexer{}
+
+// Indexer represents a basic elasticsearch indexer implementation
+type Indexer struct {
+	Client *elastic.Client
+
+	url       string
+	indexName string
+	version   int
+	mapping   string
+}
+
+func NewIndexer(url, indexName string, version int, mapping string) *Indexer {
+	return &Indexer{
+		url:       url,
+		indexName: indexName,
+		version:   version,
+		mapping:   mapping,
+	}
+}
+
+// Init initializes the indexer
+func (i *Indexer) Init(ctx context.Context) (bool, error) {
+	if i == nil {
+		return false, fmt.Errorf("cannot init nil indexer")
+	}
+	if i.Client != nil {
+		return false, fmt.Errorf("indexer is already initialized")
+	}
+
+	client, err := i.initClient()
+	if err != nil {
+		return false, err
+	}
+	i.Client = client
+
+	exists, err := i.Client.IndexExists(i.VersionedIndexName()).Do(ctx)
+	if err != nil {
+		return false, err
+	}
+	if exists {
+		return true, nil
+	}
+
+	if err := i.createIndex(ctx); err != nil {
+		return false, err
+	}
+
+	return exists, nil
+}
+
+// Ping checks if the indexer is available
+func (i *Indexer) Ping(ctx context.Context) error {
+	if i == nil {
+		return fmt.Errorf("cannot ping nil indexer")
+	}
+	if i.Client == nil {
+		return fmt.Errorf("indexer is not initialized")
+	}
+
+	resp, err := i.Client.ClusterHealth().Do(ctx)
+	if err != nil {
+		return err
+	}
+	if resp.Status != "green" && resp.Status != "yellow" {
+		// It's healthy if the status is green, and it's available if the status is yellow,
+		// see https://www.elastic.co/guide/en/elasticsearch/reference/current/cluster-health.html
+		return fmt.Errorf("status of elasticsearch cluster is %s", resp.Status)
+	}
+	return nil
+}
+
+// Close closes the indexer
+func (i *Indexer) Close() {
+	if i == nil {
+		return
+	}
+	i.Client = nil
+}
diff --git a/modules/indexer/internal/elasticsearch/util.go b/modules/indexer/internal/elasticsearch/util.go
new file mode 100644
index 0000000..18cb152
--- /dev/null
+++ b/modules/indexer/internal/elasticsearch/util.go
@@ -0,0 +1,68 @@
+// Copyright 2023 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package elasticsearch
+
+import (
+	"context"
+	"fmt"
+	"time"
+
+	"code.gitea.io/gitea/modules/log"
+
+	"github.com/olivere/elastic/v7"
+)
+
+// VersionedIndexName returns the full index name with version
+func (i *Indexer) VersionedIndexName() string {
+	return versionedIndexName(i.indexName, i.version)
+}
+
+func versionedIndexName(indexName string, version int) string {
+	if version == 0 {
+		// Old index name without version
+		return indexName
+	}
+	return fmt.Sprintf("%s.v%d", indexName, version)
+}
+
+func (i *Indexer) createIndex(ctx context.Context) error {
+	createIndex, err := i.Client.CreateIndex(i.VersionedIndexName()).BodyString(i.mapping).Do(ctx)
+	if err != nil {
+		return err
+	}
+	if !createIndex.Acknowledged {
+		return fmt.Errorf("create index %s with %s failed", i.VersionedIndexName(), i.mapping)
+	}
+
+	i.checkOldIndexes(ctx)
+
+	return nil
+}
+
+func (i *Indexer) initClient() (*elastic.Client, error) {
+	opts := []elastic.ClientOptionFunc{
+		elastic.SetURL(i.url),
+		elastic.SetSniff(false),
+		elastic.SetHealthcheckInterval(10 * time.Second),
+		elastic.SetGzip(false),
+	}
+
+	logger := log.GetLogger(log.DEFAULT)
+
+	opts = append(opts, elastic.SetTraceLog(&log.PrintfLogger{Logf: logger.Trace}))
+	opts = append(opts, elastic.SetInfoLog(&log.PrintfLogger{Logf: logger.Info}))
+	opts = append(opts, elastic.SetErrorLog(&log.PrintfLogger{Logf: logger.Error}))
+
+	return elastic.NewClient(opts...)
+}
+
+func (i *Indexer) checkOldIndexes(ctx context.Context) {
+	for v := 0; v < i.version; v++ {
+		indexName := versionedIndexName(i.indexName, v)
+		exists, err := i.Client.IndexExists(indexName).Do(ctx)
+		if err == nil && exists {
+			log.Warn("Found older elasticsearch index named %q, Forgejo will keep the old NOT DELETED. You can delete the old version after the upgrade succeed.", indexName)
+		}
+	}
+}