GraphQL入门与开源的GraphQL引擎Hasura体验

背景

Hasura 是一个开源的 GraphQL 引擎，它可以帮助开发人员快速构建和部署现代应用程序的后端。它提供了一个自动化的 GraphQL API ，可以直接连接到现有的数据库，并提供实时数据推送和订阅功能。 Hasura 团队总部位于印度。

下载安装

脚本地址：https://raw.githubusercontent.com/hasura/graphql-engine/stable/install-manifests/docker-compose/docker-compose.yaml

[root@graphql ~]# cd /opt/hasura/# 下载docker-compose.yml的编排脚本
[root@graphql hasura]# curl https://raw.githubusercontent.com/hasura/graphql-engine/stable/install-manifests/docker-compose/docker-compose.yaml -o docker-compose.yml# 启动容器
[root@graphql hasura]# docker compose up -d
[+] Running 3/3✘ Container hasura-data-connector-agent-1  Error                                                                     0.1s ✔ Container hasura-postgres-1              Running                                                                   0.0s ✔ Container hasura-graphql-engine-1        Created                                                                   0.1s 
dependency failed to start: container hasura-data-connector-agent-1 is unhealthy

遇到的问题：CPU does not support x86-64-v2

正常情况下，经过上述的安装之后就可以正常使用Hasura了，但是显然， docker compose 启动容器后显示了一条错误信息：

dependency failed to start: container hasura-data-connector-agent-1 is unhealthy

# 查看进程
[root@graphql hasura]# docker ps
CONTAINER ID   IMAGE                                   COMMAND                   CREATED          STATUS                            PORTS      NAMES
48055c1c2732   hasura/graphql-data-connector:v2.33.0   "/app/run-java.sh"        29 seconds ago   Restarting (127) 13 seconds ago              hasura-data-connector-agent-1
8e5e0f4d8cd5   postgres:15                             "docker-entrypoint.s…"   13 hours ago     Up 13 hours                       5432/tcp   hasura-postgres-1# 查看报错容器的日志信息
[root@graphql hasura]# docker logs 48055c1c2732
Fatal glibc error: CPU does not support x86-64-v2
Fatal glibc error: CPU does not support x86-64-v2
Fatal glibc error: CPU does not support x86-64-v2

原因分析
日志里说明了错误的原因，由于 CPU 架构问题。。
解决方法
那么，就换个不同的版本吧，但是从官方的发布日志里并没有找到需要的版本；换个思路， data-connector-agent 似乎是新版本才加入的，核心的 graphql-engine 能用就行，就从网络博客中找到了以下 docker-compose.yml 的编排脚本：

version: '3.6'
services:postgres:image: postgres:15restart: alwaysvolumes:- db_data:/var/lib/postgresql/dataports:- "5432:5432"environment:POSTGRES_PASSWORD: postgrespasswordgraphql-engine:image: hasura/graphql-engine:v2.24.0ports:- "8080:8080"depends_on:- "postgres"restart: alwaysenvironment:## postgres database to store Hasura metadataHASURA_GRAPHQL_METADATA_DATABASE_URL: postgres://postgres:postgrespassword@postgres:5432/postgres## this env var can be used to add the above postgres database to Hasura as a data source. this can be removed/updated based on your needsPG_DATABASE_URL: postgres://postgres:postgrespassword@postgres:5432/postgres## enable the console served by serverHASURA_GRAPHQL_ENABLE_CONSOLE: "true" # set to "false" to disable console## enable debugging mode. It is recommended to disable this in productionHASURA_GRAPHQL_DEV_MODE: "true"HASURA_GRAPHQL_ENABLED_LOG_TYPES: startup, http-log, webhook-log, websocket-log, query-log## uncomment next line to run console offline (i.e load console assets from server instead of CDN)# HASURA_GRAPHQL_CONSOLE_ASSETS_DIR: /srv/console-assets## uncomment next line to set an admin secret# HASURA_GRAPHQL_ADMIN_SECRET: myadminsecretkey
volumes:db_data:

遇到的问题：不同版本的PostgreSQL数据目录不兼容

如果一开始用的是 PostgreSQL 15 ，而重新换新的 docker-compose.yml 的编排脚本（里面是 PostgreSQL 14.X ）执行时，便会报出以下错误。

The data directory was initialized by PostgreSQL version 15, which is not compatible with this version 14.9 (Debian 14.9-1.pgdg120+1).

原因分析
docker compose 会按名称重用卷（这样就不会丢失数据）。在更换 PostgreSQL 大版本时，必须将数据迁移到新卷，如果没有任何有用的数据，则删除旧的卷。
解决方法
先删除容器，再删除未被任何容器使用的本地卷
docker volume ls # 查看本地所有的卷
docker volume prune # 删除未被任何容器使用的本地卷

[root@graphql hasura]# docker volume ls
DRIVER    VOLUME NAME
local     hasura_db_data# 这条命令并没有删除卷，接着就用下一条语句直接删除
[root@graphql hasura]# docker volume prune
WARNING! This will remove anonymous local volumes not used by at least one container.
Are you sure you want to continue? [y/N] y
Total reclaimed space: 0B[root@graphql hasura]# docker volume rm hasura_db_data
hasura_db_data
/var/lib/docker/volumes# 再次尝试启动
[root@graphql hasura]# docker compose up -d# 启动成功
[root@graphql hasura]# docker ps
CONTAINER ID   IMAGE                           COMMAND                    CREATED              STATUS                        PORTS                                       NAMES
5709437e2127   hasura/graphql-engine:v2.24.0   "/bin/sh -c '\"${HGE_…"   About a minute ago   Up About a minute (healthy)   0.0.0.0:8080->8080/tcp, :::8080->8080/tcp   hasura-graphql-engine-1
a41ec5127932   postgres:15                     "docker-entrypoint.s…"    About a minute ago   Up About a minute             0.0.0.0:5432->5432/tcp, :::5432->5432/tcp   hasura-postgres-1

连接数据源

安装启动成功后，可以打开浏览器访问控制台：http://your-host:8080/console。

可以直接使用 Hasura 自带的 PostgreSQL 作为数据源进行操作。

Hasura 本身就是基于 PostgreSQL 进行开发的，目前对其他的数据库也在做适配中，不过如果要连接 MySQL ，则需要使用其企业版。。

因此如果确实有连接 MySQL 的强需求，则可以尝试下国产版的 Hasura ：飞布。

GraphQL基本操作

关于 GraphQL 可以结合以下两个网址极速入门~~

GraphQL入门
Countries GraphQL API

基本查询

query {countries{name,codephones}
}

嵌套查询

query {countries{name,codephone,languages{code,name,native,rtl}}
}

条件查询

{countries(filter : {code:{eq: "AU"} }) {namecodephonelanguages {codenamenativertl}}
}query getCountry {country(code: "CN"){name,codephones}
}

别名

{countries(filter : {code:{eq: "AU"} }) {namecodephonelan: languages {codenamenativertl}}
}

片段

{conflictOne: countries(filter: {code: {eq: "PS"}}) {...sameField}conflictTwo: countries(filter: {code: {eq: "IL"}}) {...sameField}
}fragment sameField on Country {codenamenativelan: languages {codenamenative}
}

操作名称query

query getCounty {countries(filter : {code:{eq: "CN"} }) {namecodephonelanguages {codenamenativertl}}
}

变量

query getCounty($code: String) {countries(filter: {code: {eq: $code}}) {namecodephonelanguages {codenamenativertl}}
}{"code": "AU"
}

默认变量

query getCounty($code: String = "CN") {countries(filter: {code: {eq: $code}}) {namecodephonelanguages {codenamenativertl}}
}

指令：include，skip

query getCounty($code: String, $withLanguages: Boolean!) {countries(filter: {code: {eq: $code}}) {namecodephonelanguages @include(if: $withLanguages){codenamenativertl}states @skip(if: $withLanguages){codename}}
}{"code": "CN","withLanguages": false
}