相关文章

有使用PHP组件的朋友, 应该会注意到组件里头会有一个文件 composer.json, 它描述了组件的信息: 名称, 描述, 关键词, 作者, GitHub仓库地址...还有它所依赖的子组件, 是 Composer 工作的核心.

拿一个大家都知道的日志组件 monologcomposer.json 为例, 我说下一些比较重要的字段:

{
    "name": "monolog/monolog",
    "description": "Sends your logs to files, sockets, inboxes, databases and various web services",
    "keywords": ["log", "logging", "psr-3"],
    "homepage": "http://github.com/Seldaek/monolog",
    "type": "library",
    "license": "MIT",
    "authors": [
        {
            "name": "Jordi Boggiano",
            "email": "j.boggiano@seld.be",
            "homepage": "http://seld.be"
        }
    ],
    "require": {
        "php": "^7.0",
        "psr/log": "^1.0.1"
    },
    "require-dev": {
        "phpunit/phpunit": "^5.7",
        "graylog2/gelf-php": "^1.4.2",
        "sentry/sentry": "^0.13",
        "ruflin/elastica": ">=0.90 <3.0",
        "doctrine/couchdb": "~1.0@dev",
        "aws/aws-sdk-php": "^2.4.9 || ^3.0",
        "php-amqplib/php-amqplib": "~2.4",
        "swiftmailer/swiftmailer": "^5.3|^6.0",
        "php-console/php-console": "^3.1.3",
        "jakub-onderka/php-parallel-lint": "^0.9",
        "predis/predis": "^1.1",
        "phpspec/prophecy": "^1.6.1"
    },
    "suggest": {
        "graylog2/gelf-php": "Allow sending log messages to a GrayLog2 server",
        "sentry/sentry": "Allow sending log messages to a Sentry server",
        "doctrine/couchdb": "Allow sending log messages to a CouchDB server",
        "ruflin/elastica": "Allow sending log messages to an Elastic Search server",
        "php-amqplib/php-amqplib": "Allow sending log messages to an AMQP server using php-amqplib",
        "ext-amqp": "Allow sending log messages to an AMQP server (1.0+ required)",
        "ext-mongodb": "Allow sending log messages to a MongoDB server (via driver)",
        "mongodb/mongodb": "Allow sending log messages to a MongoDB server (via library)",
        "aws/aws-sdk-php": "Allow sending log messages to AWS services like DynamoDB",
        "rollbar/rollbar": "Allow sending log messages to Rollbar",
        "php-console/php-console": "Allow sending log messages to Google Chrome"
    },
    "autoload": {
        "psr-4": {"Monolog\\": "src/Monolog"}
    },
    "autoload-dev": {
        "psr-4": {"Monolog\\": "tests/Monolog"}
    },
    "provide": {
        "psr/log-implementation": "1.0.0"
    },
    "extra": {
        "branch-alias": {
            "dev-master": "2.0.x-dev"
        }
    },
    "scripts": {
        "test": [
            "parallel-lint . --exclude vendor",
            "phpunit"
        ]
    }
}

安装依赖的时候, 最重要的字段是 name, require 以及 require-dev.

name

该字段标识了组件的名称, 在 所有 的组件中, 它是唯一的;

require

该字段列举出该组件 所需的运行环境 以及 依赖的子组件的版本, 安装该组件时, 会检测运行环境, 并安装该组件的子组件, 以及这些子组件的所有子组件...直到子组件不再依赖任何组件为止;

require-dev

该字段不是必须的, 一般来说不安装里面的依赖, 也是可以用的, 通常都是用来跑单元测试. 依赖的安装同 require 字段.

其他字段对于理解镜像的原理没什么帮助, 有兴趣可以看下 这篇文章.

安装依赖的过程, 其实就是请求服务器, 要求拿到该组件的 composer.json 文件, 然后 JSON 解析, 得到 requirerequire-dev 字段的组件, 一直遍历下去, 根据文件描述的仓库地址 git clone 到本地.

看过我 上一篇文章 的朋友就知道, 文章末尾我们配置了 国内的composer镜像, 用来加速我们安装组件的过程, 它缓存了所有包的 composer.json, 并把仓库的每一个分支源码, 打包为 zip 压缩包, 并结合 cdn 加速.

镜像服务器提供了让我们得到 composer.json 的接口, 我们只需提交一个包名, 还有请求结果的哈希值(是不是很懵逼, 我怎么知道结果的哈希值), 镜像服务器会返回一个 JSON, 它包含了很多 composer.json (至少一个), 这些 composer.json 里面就有我们要找的组件的 composer.json (根据name字段), 也包括了其他包的, 为什么会带有其他包的呢, 我捣鼓了挺多次, 发现是当 require 字段存在时, 它就顺带返回了, 不过也不是绝对的, 可能考虑体积关系, 也不会返回太多.

说了这么多, 看下 psr/log 组件的请求结果吧, 比较长, 它包含了5个包的信息:

hackification/log
mobio/target
notadd/wechat
psr/log
wedeto/log
{
    "packages":{
        "hackification/log":{
            "1.0.2":{
                "name":"hackification/log",
                "description":"Common interface for logging libraries",
                "keywords":[
                    "log",
                    "psr",
                    "psr-3",
                    "hack",
                    "hacklang"
                ],
                "homepage":"https://github.com/hackification/log",
                "version":"1.0.2",
                "version_normalized":"1.0.2.0",
                "license":[
                    "MIT"
                ],
                "authors":[
                    {
                        "name":"PHP-FIG",
                        "homepage":"http://www.php-fig.org/"
                    }
                ],
                "source":{
                    "type":"git",
                    "url":"https://github.com/hackification/log.git",
                    "reference":"75b02e14bd8e5b8ded75de91d7eb9df6046f7fa7"
                },
                "dist":{
                    "type":"zip",
                    "url":"https://files.phpcomposer.com/files/hackification/log/75b02e14bd8e5b8ded75de91d7eb9df6046f7fa7.zip",
                    "reference":"75b02e14bd8e5b8ded75de91d7eb9df6046f7fa7",
                    "shasum":""
                },
                "type":"library",
                "time":"2016-11-08T15:32:34+00:00",
                "autoload":{
                    "psr-4":{
                        "Psr\Log\":"Psr/Log/"
                    }
                },
                "extra":{
                    "branch-alias":{
                        "dev-master":"1.0.x-dev"
                    }
                },
                "require":{
                    "hhvm":">=3.0.0"
                },
                "replace":{
                    "psr/log":"*"
                },
                "uid":1072563
            },
            "dev-master":{
                "name":"hackification/log",
                "description":"Common interface for logging libraries",
                "keywords":[
                    "log",
                    "psr",
                    "psr-3",
                    "hack",
                    "hacklang"
                ],
                "homepage":"https://github.com/hackification/log",
                "version":"dev-master",
                "version_normalized":"9999999-dev",
                "license":[
                    "MIT"
                ],
                "authors":[
                    {
                        "name":"PHP-FIG",
                        "homepage":"http://www.php-fig.org/"
                    }
                ],
                "source":{
                    "type":"git",
                    "url":"https://github.com/hackification/log.git",
                    "reference":"75b02e14bd8e5b8ded75de91d7eb9df6046f7fa7"
                },
                "dist":{
                    "type":"zip",
                    "url":"https://files.phpcomposer.com/files/hackification/log/75b02e14bd8e5b8ded75de91d7eb9df6046f7fa7.zip",
                    "reference":"75b02e14bd8e5b8ded75de91d7eb9df6046f7fa7",
                    "shasum":""
                },
                "type":"library",
                "time":"2016-11-08T15:32:34+00:00",
                "autoload":{
                    "psr-4":{
                        "Psr\Log\":"Psr/Log/"
                    }
                },
                "extra":{
                    "branch-alias":{
                        "dev-master":"1.0.x-dev"
                    }
                },
                "require":{
                    "hhvm":">=3.0.0"
                },
                "replace":{
                    "psr/log":"*"
                },
                "uid":1072564
            }
        },
        "mobio/target":{
            "0.0.5":{
                "name":"mobio/target",
                "description":"PHP library for myTarget API",
                "keywords":[
                    "php",
                    "myTarget"
                ],
                "homepage":"",
                "version":"0.0.5",
                "version_normalized":"0.0.5.0",
                "license":[
                    "MIT"
                ],
                "authors":[

                ],
                "source":{
                    "type":"git",
                    "url":"https://github.com/MobioInc/target.git",
                    "reference":"5baeaae1aa7d85c5b5fd4e33a06608a1de93d73b"
                },
                "dist":{
                    "type":"zip",
                    "url":"https://files.phpcomposer.com/files/MobioInc/target/5baeaae1aa7d85c5b5fd4e33a06608a1de93d73b.zip",
                    "reference":"5baeaae1aa7d85c5b5fd4e33a06608a1de93d73b",
                    "shasum":""
                },
                "type":"library",
                "time":"2016-10-31T08:52:52+00:00",
                "autoload":{
                    "psr-4":{
                        "Mobio\Target\":"src/"
                    }
                },
                "require":{
                    "php":">=5.5.0",
                    "psr/log":"~1.0",
                    "guzzlehttp/guzzle":"^6.1"
                },
                "require-dev":{
                    "phpunit/phpunit":"^5.5"
                },
                "provide":{
                    "psr/log":"1.0.0"
                },
                "uid":1060012
            },
            "dev-master":{
                "name":"mobio/target",
                "description":"PHP library for myTarget API",
                "keywords":[
                    "php",
                    "myTarget"
                ],
                "homepage":"",
                "version":"dev-master",
                "version_normalized":"9999999-dev",
                "license":[
                    "MIT"
                ],
                "authors":[

                ],
                "source":{
                    "type":"git",
                    "url":"https://github.com/MobioInc/target.git",
                    "reference":"70aa382ca6d3ba3b5a834bbe85d3fc2cbfec965f"
                },
                "dist":{
                    "type":"zip",
                    "url":"https://files.phpcomposer.com/files/MobioInc/target/70aa382ca6d3ba3b5a834bbe85d3fc2cbfec965f.zip",
                    "reference":"70aa382ca6d3ba3b5a834bbe85d3fc2cbfec965f",
                    "shasum":""
                },
                "type":"library",
                "time":"2017-02-13T18:53:10+00:00",
                "autoload":{
                    "psr-4":{
                        "Mobio\Target\":"src/"
                    }
                },
                "require":{
                    "php":">=5.5.0",
                    "guzzlehttp/guzzle":"^6.1",
                    "psr/log":"~1.0"
                },
                "require-dev":{
                    "phpunit/phpunit":"^5.5"
                },
                "provide":{
                    "psr/log":"1.0.0"
                },
                "uid":700331
            }
        },
        "notadd/wechat":{
            "dev-master":{
                "name":"notadd/wechat",
                "description":"Notadd's Wechat Module.",
                "keywords":[
                    "framework",
                    "cms",
                    "member",
                    "notadd"
                ],
                "homepage":"https://notadd.com",
                "version":"dev-master",
                "version_normalized":"9999999-dev",
                "license":[
                    "Apache-2.0"
                ],
                "authors":[
                    {
                        "name":"Notadd",
                        "email":"notadd@ibenchu.com"
                    }
                ],
                "source":{
                    "type":"git",
                    "url":"https://github.com/notadd/wechat.git",
                    "reference":"e3f684cd225f3fadf21953c0289cb8426baad0e5"
                },
                "dist":{
                    "type":"zip",
                    "url":"https://files.phpcomposer.com/files/notadd/wechat/e3f684cd225f3fadf21953c0289cb8426baad0e5.zip",
                    "reference":"e3f684cd225f3fadf21953c0289cb8426baad0e5",
                    "shasum":""
                },
                "type":"notadd-module",
                "time":"2017-11-13T04:23:05+00:00",
                "autoload":{
                    "psr-4":{
                        "Notadd\Wechat\":"src/"
                    }
                },
                "require":{
                    "php":">=7.0",
                    "overtrue/wechat":"~3.1"
                },
                "require-dev":{
                    "notadd/installers":"0.14.*",
                    "notadd/testing":"0.4.*",
                    "phpunit/phpunit":"~6.0"
                },
                "replace":{
                    "guzzlehttp/guzzle":"*",
                    "guzzlehttp/promises":"*",
                    "guzzlehttp/psr7":"*",
                    "monolog/monolog":"*",
                    "psr/container":"*",
                    "psr/http-message":"*",
                    "psr/log":"*",
                    "symfony/http-foundation":"*",
                    "symfony/polyfill-mbstring":"*",
                    "symfony/psr-http-message-bridge":"*"
                },
                "uid":1108963
            }
        },
        "psr/log":{
            "1.0.0":{
                "name":"psr/log",
                "description":"Common interface for logging libraries",
                "keywords":[
                    "log",
                    "psr",
                    "psr-3"
                ],
                "homepage":"",
                "version":"1.0.0",
                "version_normalized":"1.0.0.0",
                "license":[
                    "MIT"
                ],
                "authors":[
                    {
                        "name":"PHP-FIG",
                        "homepage":"http://www.php-fig.org/"
                    }
                ],
                "source":{
                    "type":"git",
                    "url":"https://github.com/php-fig/log.git",
                    "reference":"fe0936ee26643249e916849d48e3a51d5f5e278b"
                },
                "dist":{
                    "type":"zip",
                    "url":"https://files.phpcomposer.com/files/php-fig/log/fe0936ee26643249e916849d48e3a51d5f5e278b.zip",
                    "reference":"fe0936ee26643249e916849d48e3a51d5f5e278b",
                    "shasum":""
                },
                "type":"library",
                "time":"2012-12-21T11:40:51+00:00",
                "autoload":{
                    "psr-0":{
                        "Psr\Log\":""
                    }
                },
                "uid":29358
            },
            "1.0.1":{
                "name":"psr/log",
                "description":"Common interface for logging libraries",
                "keywords":[
                    "log",
                    "psr",
                    "psr-3"
                ],
                "homepage":"https://github.com/php-fig/log",
                "version":"1.0.1",
                "version_normalized":"1.0.1.0",
                "license":[
                    "MIT"
                ],
                "authors":[
                    {
                        "name":"PHP-FIG",
                        "homepage":"http://www.php-fig.org/"
                    }
                ],
                "source":{
                    "type":"git",
                    "url":"https://github.com/php-fig/log.git",
                    "reference":"5277094ed527a1c4477177d102fe4c53551953e0"
                },
                "dist":{
                    "type":"zip",
                    "url":"https://files.phpcomposer.com/files/php-fig/log/5277094ed527a1c4477177d102fe4c53551953e0.zip",
                    "reference":"5277094ed527a1c4477177d102fe4c53551953e0",
                    "shasum":""
                },
                "type":"library",
                "time":"2016-09-19T16:02:08+00:00",
                "autoload":{
                    "psr-4":{
                        "Psr\Log\":"Psr/Log/"
                    }
                },
                "extra":{
                    "branch-alias":{
                        "dev-master":"1.0.x-dev"
                    }
                },
                "require":{
                    "php":">=5.3.0"
                },
                "uid":1000789
            },
            "1.0.2":{
                "name":"psr/log",
                "description":"Common interface for logging libraries",
                "keywords":[
                    "log",
                    "psr",
                    "psr-3"
                ],
                "homepage":"https://github.com/php-fig/log",
                "version":"1.0.2",
                "version_normalized":"1.0.2.0",
                "license":[
                    "MIT"
                ],
                "authors":[
                    {
                        "name":"PHP-FIG",
                        "homepage":"http://www.php-fig.org/"
                    }
                ],
                "source":{
                    "type":"git",
                    "url":"https://github.com/php-fig/log.git",
                    "reference":"4ebe3a8bf773a19edfe0a84b6585ba3d401b724d"
                },
                "dist":{
                    "type":"zip",
                    "url":"https://files.phpcomposer.com/files/php-fig/log/4ebe3a8bf773a19edfe0a84b6585ba3d401b724d.zip",
                    "reference":"4ebe3a8bf773a19edfe0a84b6585ba3d401b724d",
                    "shasum":""
                },
                "type":"library",
                "time":"2016-10-10T12:19:37+00:00",
                "autoload":{
                    "psr-4":{
                        "Psr\Log\":"Psr/Log/"
                    }
                },
                "extra":{
                    "branch-alias":{
                        "dev-master":"1.0.x-dev"
                    }
                },
                "require":{
                    "php":">=5.3.0"
                },
                "uid":1029935
            },
            "dev-master":{
                "name":"psr/log",
                "description":"Common interface for logging libraries",
                "keywords":[
                    "log",
                    "psr",
                    "psr-3"
                ],
                "homepage":"https://github.com/php-fig/log",
                "version":"dev-master",
                "version_normalized":"9999999-dev",
                "license":[
                    "MIT"
                ],
                "authors":[
                    {
                        "name":"PHP-FIG",
                        "homepage":"http://www.php-fig.org/"
                    }
                ],
                "source":{
                    "type":"git",
                    "url":"https://github.com/php-fig/log.git",
                    "reference":"4ebe3a8bf773a19edfe0a84b6585ba3d401b724d"
                },
                "dist":{
                    "type":"zip",
                    "url":"https://files.phpcomposer.com/files/php-fig/log/4ebe3a8bf773a19edfe0a84b6585ba3d401b724d.zip",
                    "reference":"4ebe3a8bf773a19edfe0a84b6585ba3d401b724d",
                    "shasum":""
                },
                "type":"library",
                "time":"2016-10-10T12:19:37+00:00",
                "autoload":{
                    "psr-4":{
                        "Psr\Log\":"Psr/Log/"
                    }
                },
                "extra":{
                    "branch-alias":{
                        "dev-master":"1.0.x-dev"
                    }
                },
                "require":{
                    "php":">=5.3.0"
                },
                "uid":29285
            }
        },
        "wedeto/log":{
            "v0.9.1":{
                "name":"wedeto/log",
                "description":"Wedeto Platform - Logger",
                "keywords":[

                ],
                "homepage":"https://wedeto.net/",
                "version":"v0.9.1",
                "version_normalized":"0.9.1.0",
                "license":[
                    "MIT"
                ],
                "authors":[
                    {
                        "name":"Egbert van der Wal",
                        "email":"ewal@pointpro.nl"
                    }
                ],
                "source":{
                    "type":"git",
                    "url":"https://github.com/Wedeto/Log.git",
                    "reference":"acc7f4aa66965dd2627a3886c9ac8b0d77b0a268"
                },
                "dist":{
                    "type":"zip",
                    "url":"https://files.phpcomposer.com/files/Wedeto/Log/acc7f4aa66965dd2627a3886c9ac8b0d77b0a268.zip",
                    "reference":"acc7f4aa66965dd2627a3886c9ac8b0d77b0a268",
                    "shasum":""
                },
                "type":"library",
                "time":"2017-04-10T12:31:55+00:00",
                "autoload":{
                    "psr-4":{
                        "Wedeto\Log\":"src/"
                    }
                },
                "require":{
                    "psr/log":"1.0.*",
                    "wedeto/util":"0.9.*",
                    "php":">=7.0.0"
                },
                "require-dev":{
                    "mikey179/vfsstream":"~1"
                },
                "provide":{
                    "psr/log":"1.0.*"
                },
                "uid":1336127
            },
            "v0.9.2":{
                "name":"wedeto/log",
                "description":"Wedeto Platform - Logger",
                "keywords":[

                ],
                "homepage":"https://wedeto.net/",
                "version":"v0.9.2",
                "version_normalized":"0.9.2.0",
                "license":[
                    "MIT"
                ],
                "authors":[
                    {
                        "name":"Egbert van der Wal",
                        "email":"ewal@pointpro.nl"
                    }
                ],
                "source":{
                    "type":"git",
                    "url":"https://github.com/Wedeto/Log.git",
                    "reference":"55e6b03f0b446b7054078fd8a680ad1499d26264"
                },
                "dist":{
                    "type":"zip",
                    "url":"https://files.phpcomposer.com/files/Wedeto/Log/55e6b03f0b446b7054078fd8a680ad1499d26264.zip",
                    "reference":"55e6b03f0b446b7054078fd8a680ad1499d26264",
                    "shasum":""
                },
                "type":"library",
                "time":"2017-04-10T18:15:36+00:00",
                "autoload":{
                    "psr-4":{
                        "Wedeto\Log\":"src/"
                    }
                },
                "require":{
                    "psr/log":"1.0.*",
                    "wedeto/util":"0.9.*",
                    "php":">=7.0.0"
                },
                "require-dev":{
                    "mikey179/vfsstream":"~1"
                },
                "provide":{
                    "psr/log":"1.0.*"
                },
                "uid":1336697
            }
        }
    }
}

可以看到, packages 字段里面有5个包, 里面的 psr/log 字段就是我们要找的, 而里面有各个分支的 composer.json, 以分支 1.0.0 为例, 里面有两个很关键的字段, sourcedist:

{
    "source":{
        "type":"git",
        "url":"https://github.com/php-fig/log.git",
        "reference":"fe0936ee26643249e916849d48e3a51d5f5e278b"
    },
    "dist":{
        "type":"zip",
        "url":"https://files.phpcomposer.com/files/php-fig/log/fe0936ee26643249e916849d48e3a51d5f5e278b.zip",
        "reference":"fe0936ee26643249e916849d48e3a51d5f5e278b",
        "shasum":""
    }
}

dist

该字段其实就是加速的 zip 压缩包, 无需 git clone, 只需把 zip 下载到本地, 解压完, 分支 1.0.0 就装好了.

source

这个字段的作用, 就是万一 dist 字段的 zip 下载不了, 不会马上中断整个安装流程, 而是接着 git clone. 也就是说, dist 字段失败, 或者压根就没有 dist 字段, 就走 source 字段.


看到这里, 对 Composer 的了解应该多了很多吧? 还记得 请求结果的哈希值 吗? 这个哈希哪里来的, 为什么我可以提前知道这个请求的 JSON 的哈希值? 还有, 接口在哪里? 镜像服务器的官方网站, 并没有提供啊...

下一篇文章再告诉你.

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