Convert Drupal 8.6 site to Composer (after D8 end of life)? [closed]

Question

Client has a sqldump and a tarball of a broken Drupal site.

Instead of using Composer to set up the recommended project, it looks like the previous developer performed a git checkout of http://git.drupal.org/project/drupal circa Drupal 8.6.15 :anguished:.

I'd like to Composerize the project before attempting to update Drupal from D8 to D9, but it looks like I can no longer composer require "drupal/core-recommended": :8.6.15":

$ ddev composer install
No composer.lock file present. Updating dependencies to latest instead of installing from lock file. See https://getcomposer.org/install for more information.
Loading composer repositories with package information
Updating dependencies
Your requirements could not be resolved to an installable set of packages.

  Problem 1
    - composer/installers v1.5.0 requires composer-plugin-api ^1.0 -> found composer-plugin-api[2.3.0] but it does not match the constraint.
    - drupal/core-recommended 8.6.15 requires composer/installers v1.5.0 -> satisfiable by composer/installers[v1.5.0].
    - Root composer.json requires drupal/core-recommended 8.6.15 -> satisfiable by drupal/core-recommended[8.6.15].

composer [install] failed, composer command failed: exit status 2. stderr=

What's the best practice here?

Answer 1

Steps to create locally in DDEV:

mkdir testd9
cd testd9
ddev config
# defaults to: testd9, current folder, PHP
ddev composer create drupal/recommended-project:9.5.1 --no-install
nano composer.json
# change composer/installers to 1.5
# temporarily remove drupal/core-composer-scaffold to 8.6.15
# temporarily remove drupal/core-project-message to 8.6.15
# change drupal/core-recommended to 8.6.15
# save
nano .ddev/config.yaml
# change php_version to 7.4
# change composer_version to 1
# save
rm composer.lock
ddev restart
ddev composer install
ddev config
# defaults to testd9, web, drupal8
# load database
# load files folder
# test install
# upgrade to different drupal version.
# composer/installers will need to be upgraded occaisionally.
# at 8.8 it will require the drupal-core-composer-scaffold Keep in sync with drupal/core-recommended
# drupal/core-project-message is not needed.

resulting composer.json:

{
    "name": "drupal/recommended-project",
    "description": "Project template for Drupal 9 projects with a relocated document root",
    "type": "project",
    "license": "GPL-2.0-or-later",
    "homepage": "https://www.drupal.org/project/drupal",
    "support": {
        "docs": "https://www.drupal.org/docs/user_guide/en/index.html",
        "chat": "https://www.drupal.org/node/314178"
    },
    "repositories": [
        {
            "type": "composer",
            "url": "https://packages.drupal.org/8"
        }
    ],
    "require": {
        "composer/installers": "1.5",
        "drupal/core-recommended": "8.6.15"
    },
    "conflict": {
        "drupal/drupal": "*"
    },
    "minimum-stability": "stable",
    "prefer-stable": true,
    "config": {
        "allow-plugins": {
            "composer/installers": true,
            "drupal/core-composer-scaffold": true,
            "drupal/core-project-message": true,
            "dealerdirect/phpcodesniffer-composer-installer": true
        },
        "sort-packages": true
    },
    "extra": {
        "drupal-scaffold": {
            "locations": {
                "web-root": "web/"
            }
        },
        "installer-paths": {
            "web/core": [
                "type:drupal-core"
            ],
            "web/libraries/{$name}": [
                "type:drupal-library"
            ],
            "web/modules/contrib/{$name}": [
                "type:drupal-module"
            ],
            "web/profiles/contrib/{$name}": [
                "type:drupal-profile"
            ],
            "web/themes/contrib/{$name}": [
                "type:drupal-theme"
            ],
            "drush/Commands/contrib/{$name}": [
                "type:drupal-drush"
            ],
            "web/modules/custom/{$name}": [
                "type:drupal-custom-module"
            ],
            "web/profiles/custom/{$name}": [
                "type:drupal-custom-profile"
            ],
            "web/themes/custom/{$name}": [
                "type:drupal-custom-theme"
            ]
        },
        "drupal-core-project-message": {
            "include-keys": [
                "homepage",
                "support"
            ],
            "post-create-project-cmd-message": [
                "<bg=blue;fg=white>                                                         </>",
                "<bg=blue;fg=white>  Congratulations, you’ve installed the Drupal codebase  </>",
                "<bg=blue;fg=white>  from the drupal/recommended-project template!          </>",
                "<bg=blue;fg=white>                                                         </>",
                "",
                "<bg=yellow;fg=black>Next steps</>:",
                "  * Install the site: https://www.drupal.org/docs/installing-drupal",
                "  * Read the user guide: https://www.drupal.org/docs/user_guide/en/index.html",
                "  * Get support: https://www.drupal.org/support",
                "  * Get involved with the Drupal community:",
                "      https://www.drupal.org/getting-involved",
                "  * Remove the plugin that prints this message:",
                "      composer remove drupal/core-project-message"
            ]
        }
    }
}