⚠️ 警告

这些包处于开发的早期 MVP 阶段。您可能已经使用它们，它们将为您提供足够的功能子集，但可能尚未涵盖一些高级用例。

包	docs.rs	crates.io
migrate
migrate-core
migrate-state
migrate-state-dynamodb
migrate-state-file
migrate-state-test

“master”分支的文档可在此处找到。

migrate

migrate 是一个通用迁移工具。它为 Rust 中编写迁移脚本提供灵活的接口，并为您处理迁移状态。

概述

migrate 能够迁移任何类型的外部状态：生产数据库、云资源等。它监控应应用或回滚的迁移。在更高级的设置中，migrate 使用外部锁防止数据竞争，确保在任何时刻只有一个迁移在运行（目前尚未实现）。

在基本情况下，您应该能够仅实现 up 方法，并（可选）实现 down 方法。

示例模板

use async_trait::async_trait;
use migrate::MigrateCli;
use migrate::core::{Migration, Plan, MigrationCtxProvider};
use std::error::Error;
use rusoto_dynamodb::DynamoDb;

// File where `migrate` CLI will record the list of allready applied migrations
// This is called the migration state and there are several different backends
// that implement it. You may also implement your own, e.g. store the migration
// state in your own database.
// See the list of ready-to-use state backends bellow.
const MIGRATION_STATE_FILE_PATH: &str = "./migration-state";

type Result<T, E = Box<dyn Error + Send + Sync>> = std::result::Result<T, E>;

struct MyMigration;

#[async_trait]
impl Migration for MyMigration {
    type Ctx = rusoto_dynamodb::DynamoDbClient;

    async fn up(&mut self, ctx: &mut Self::Ctx) -> Result<()> {
        // Apply forward migration logic with the given context
        ctx.put_item(todo!()).await?;
    }

    async fn down(&mut self, ctx: &mut Self::Ctx) -> Result<()> {
        // Rollback the applied migration.
        // Ideally this should be purely inverse to up()
        ctx.delete_item(todo!()).await?;
    }
}

#[tokio::main]
async fn main() -> Result<()> {
    let state_storage = migrate_state_file::FileStateLock::new(MIGRATION_STATE_FILE_PATH);

    let mut plan = Plan::builder(state_storage);

    plan.ctx_provider(DynamoDbClientProvider)
        // Add migrations in order one after each other to the plan
        .migration("migration-1", MyMigration);

    // Run the `migrate` cli to get the parameters of how to
    // build and execute the rest of the migration plan
    // let cli = migrate::MigrateCli::from_cli_args();

    // Run the CLI (this is run in a test, it's commented out not to run CLI)
    // cli.run(plan).await?;

    Ok(())
}

struct DynamoDbClientProvider;

#[async_trait]
impl MigrationCtxProvider for DynamoDbClientProvider {
    type Ctx = rusoto_dynamodb::DynamoDbClient;

    async fn create_in_commit_mode(self: Box<Self>) -> Result<Self::Ctx> {
        // Create real database client that will do real changes on real data
        todo!()
    }

    async fn create_in_no_commit_mode(self: Box<Self>) -> Option<Result<Self::Ctx>> {
        // We can provide some mocked implementation of database client here
        // via the usage of traits or enums so that the client doesn't commit changes to the database
        todo!()
    }
}

可用的迁移状态后端

• DynamoDb: migrate_state_dynamodb
• 本地文件: migrate_state_file

锁定

migrate 应支持状态锁定以防止数据竞争（并发迁移）。此功能尚未实现，但计划在 1.0 版本中实现...

新的迁移初始化

migrate 命令行界面应该有一个子命令用于创建新的迁移模板，该模板应由迁移上下文特性实现进行配置。此功能也计划在 1.0 版本中实现，但尚未实现...

目标

• 方便和灵活的 API
• 一致性

非目标

• 性能

贡献

欢迎任何贡献，只需确保通过所需的 CI 检查即可 :D

参考文献

“迁移”这一想法最初是受到了east迁移工具（来自TypeScript领域）的启发。

许可证