chore: import upstream snapshot with attribution

internal/tools/postgres/postgresreplicationstats/postgresreplicationstats.go

@@ -0,0 +1,126 @@
+// Copyright 2025 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package postgresreplicationstats
+
+import (
+	"context"
+	"fmt"
+	"net/http"
+
+	yaml "github.com/goccy/go-yaml"
+	"github.com/googleapis/mcp-toolbox/internal/tools"
+	"github.com/googleapis/mcp-toolbox/internal/util"
+	"github.com/googleapis/mcp-toolbox/internal/util/parameters"
+	"github.com/jackc/pgx/v5/pgxpool"
+)
+
+const resourceType string = "postgres-replication-stats"
+
+const replicationStats = `
+    SELECT
+        pid,
+        usename,
+        application_name,
+        backend_xmin,
+        client_addr,
+        state,
+        sync_state,
+        pg_size_pretty(pg_wal_lsn_diff(pg_current_wal_lsn(), sent_lsn)) AS sent_lag,
+        pg_size_pretty(pg_wal_lsn_diff(sent_lsn, write_lsn)) AS write_lag,
+        pg_size_pretty(pg_wal_lsn_diff(write_lsn, flush_lsn)) AS flush_lag,
+        pg_size_pretty(pg_wal_lsn_diff(flush_lsn, replay_lsn)) AS replay_lag,
+        pg_size_pretty(pg_wal_lsn_diff(pg_current_wal_lsn(), replay_lsn)) AS total_lag
+    FROM
+        pg_stat_replication;
+`
+
+func init() {
+	if !tools.Register(resourceType, newConfig) {
+		panic(fmt.Sprintf("tool type %q already registered", resourceType))
+	}
+}
+
+func newConfig(ctx context.Context, name string, decoder *yaml.Decoder) (tools.ToolConfig, error) {
+	actual := Config{ConfigBase: tools.ConfigBase{Name: name}}
+	if err := decoder.DecodeContext(ctx, &actual); err != nil {
+		return nil, err
+	}
+	return actual, nil
+}
+
+type compatibleSource interface {
+	PostgresPool() *pgxpool.Pool
+	RunSQL(context.Context, string, []any) (any, error)
+}
+
+type Config struct {
+	tools.ConfigBase `yaml:",inline"`
+	Type             string                 `yaml:"type" validate:"required"`
+	Source           string                 `yaml:"source" validate:"required"`
+	Annotations      *tools.ToolAnnotations `yaml:"annotations,omitempty"`
+}
+
+var _ tools.ToolConfig = Config{}
+
+func (cfg Config) ToolConfigType() string {
+	return resourceType
+}
+
+func (cfg Config) Initialize(context.Context) (tools.Tool, error) {
+	allParameters := parameters.Parameters{}
+
+	if cfg.Description == "" {
+		cfg.Description = "Lists each replica's process ID, user name, application name, backend_xmin (standby's xmin horizon reported by hot_standby_feedback), client IP address, connection state, and sync_state, along with lag sizes in bytes for sent_lag (primary to sent), write_lag (sent to written), flush_lag (written to flushed), replay_lag (flushed to replayed), and the overall total_lag (primary to replayed)."
+	}
+
+	return Tool{
+		BaseTool: tools.NewBaseTool(
+			cfg,
+			tools.GetAnnotationsOrDefault(cfg.Annotations, tools.NewReadOnlyAnnotations),
+			tools.Manifest{Description: cfg.Description, Parameters: allParameters.Manifest(), AuthRequired: cfg.AuthRequired},
+			allParameters,
+		),
+	}, nil
+}
+
+var _ tools.Tool = Tool{}
+
+type Tool struct {
+	tools.BaseTool[Config]
+}
+
+func (t Tool) Invoke(ctx context.Context, resourceMgr tools.SourceProvider, params parameters.ParamValues, accessToken tools.AccessToken) (any, util.ToolboxError) {
+	source, err := tools.GetCompatibleSource[compatibleSource](resourceMgr, t.Cfg.Source, t.Cfg.Name, t.Cfg.Type)
+	if err != nil {
+		return nil, util.NewClientServerError("source used is not compatible with the tool", http.StatusInternalServerError, err)
+	}
+
+	paramsMap := params.AsMap()
+
+	newParams, err := parameters.GetParams(t.StaticParameters, paramsMap)
+	if err != nil {
+		return nil, util.NewAgentError("unable to extract standard params", err)
+	}
+	sliceParams := newParams.AsSlice()
+	resp, err := source.RunSQL(ctx, replicationStats, sliceParams)
+	if err != nil {
+		return nil, util.ProcessGeneralError(err)
+	}
+	return resp, nil
+}
+
+func (t Tool) ToConfig() tools.ToolConfig {
+	return t.Cfg
+}