feat: 接入 Instance 原生管理观测与删除保护

internal/database/adapter/postgresql/management.go

@@ -0,0 +1,58 @@
+package postgresql
+
+import (
+	"context"
+
+	"git.ddupan.top/panxiao81/ayatori/internal/database/application"
+	"git.ddupan.top/panxiao81/ayatori/internal/database/domain/instance"
+)
+
+// 只读取当前执行角色的属性，不能从可继承的角色成员关系推导 CREATEDB/CREATEROLE。
+// 所有事实来自同一条语句；不创建探针数据库，不修改管理账号或持久 schema。
+const inspectManagementStatement = `
+SELECT
+    pg_catalog.current_setting('server_version'),
+    ARRAY(SELECT name::text FROM pg_catalog.pg_available_extensions ORDER BY name),
+    role.rolsuper,
+    role.rolcreaterole,
+    role.rolcreatedb,
+    pg_catalog.pg_is_in_recovery() OR
+        pg_catalog.current_setting('transaction_read_only')::boolean
+FROM pg_catalog.pg_roles AS role
+WHERE role.rolname = current_user`
+
+func (d *database) InspectManagement(ctx context.Context) (application.DatabaseMetadata, error) {
+	var metadata application.DatabaseMetadata
+	var superuser, createRole, createDatabase, readOnly bool
+	err := d.pool.QueryRow(ctx, inspectManagementStatement).Scan(
+		&metadata.Version, &metadata.AvailableExtensions,
+		&superuser, &createRole, &createDatabase, &readOnly,
+	)
+	if err != nil {
+		return application.DatabaseMetadata{}, safeError(err, application.ErrObservation)
+	}
+	checks := instance.ManagementChecks{
+		Connection: instance.CheckPassed,
+		Metadata:   instance.CheckPassed,
+		Roles:      nativePrivilege(createRole && !superuser),
+		Databases:  nativePrivilege(createDatabase && !superuser),
+		// CREATEROLE 可管理自己新建角色的 membership；供应时必须显式取得 SET 权限，
+		// 再以 owner 操作数据库 ACL。这里不授权操作任意导入角色或他人数据库。
+		Grants: nativePrivilege(createRole && createDatabase && !superuser),
+		// 新建数据库 owner 可安装 trusted 扩展。具体扩展仍需逐请求执行和回读，
+		// 非 trusted 扩展不能因出现在 available 列表就视为可安装。
+		Extensions: nativePrivilege(createRole && createDatabase && !superuser),
+	}
+	if readOnly {
+		checks.Databases = instance.CheckUnavailable
+	}
+	metadata.Management = checks
+	return metadata, nil
+}
+
+func nativePrivilege(allowed bool) instance.CheckResult {
+	if allowed {
+		return instance.CheckPassed
+	}
+	return instance.CheckInsufficientPrivileges
+}