composer add custom module to magento2

Magento_composer.json

{
  "name": "magento/magento2ce",
  "description": "Magento 2 My project",
  "type": "project",
  "version": "2.2.7",
  "license": [
    "OSL-3.0",
    "AFL-3.0"
  ],
  "require": {
    "magento/product-community-edition": "2.2.7",
    "composer/composer": "@alpha",
   "VENDOR/magento2-module-MODULENAME": "VERSION CONSTRAINT"
    //....
  },
   "autoload": {
    "psr-4": {
      "Magento\\Framework\\": "lib/internal/Magento/Framework/",
      "Magento\\Setup\\": "setup/src/Magento/Setup/",
      "Magento\\": "app/code/Magento/"
    },
    "psr-0": {
      "": [
        "app/code/"
      ]
    },
    "files": [
      "app/etc/NonComposerComponentRegistration.php"
    ],
    "exclude-from-classmap": [
      "**/dev/**",
      "**/update/**",
      "**/Test/**"
    ]
  },
  "autoload-dev": {
    "psr-4": {
      "Magento\\Sniffs\\": "dev/tests/static/framework/Magento/Sniffs/",
      "Magento\\Tools\\": "dev/tools/Magento/Tools/",
      "Magento\\Tools\\Sanity\\": "dev/build/publication/sanity/Magento/Tools/Sanity/",
      "Magento\\TestFramework\\Inspection\\": "dev/tests/static/framework/Magento/TestFramework/Inspection/",
      "Magento\\TestFramework\\Utility\\": "dev/tests/static/framework/Magento/TestFramework/Utility/"
    }
  },
  "minimum-stability": "stable",
  "repositories": {
    "0": {
      "type": "composer",
      "url": "https://repo.magento.com/"
    },
    "mycustommodule": {
      "type": "vcs",
      "url": "https://github.com/mycompany/privaterepo"
    }
  }
}

Module_composer.json

{
  "name": "VENDOR/magento2-module-MODULENAME",
  "license": "OSL-3.0",
  "description": "Magento2 custom module",
  "require": {
    "php": "^7.0|^7.1",
    "ext-pcre": "*",
    "magento/framework": "^101.0",
    "magento/module-backend": "^100.2",
    "magento/module-catalog": "^102.0",
    "magento/module-store": "^100.2",
    "magento/module-eav": "^101.0",
    "magento/module-ui": "^101.0",
    "magento/module-config": "^101.0",
    "psr/log": "^1.1"
  },
  "type": "magento2-module",
  "autoload": {
    "files": [
      "registration.php"
    ],
    "psr-4": {
      "VENDOR\\MODULENAME\\": ""
    }
  }
}