Preparing for Drupal 8 migration
Preparing servers
Since Drupal 7 to Drupal 8 is not done on single instance, We have to install fresh Drupal 8 and migrate content and themes to new Drupal 8 instance.
Upgrading Drupal 7 to latest drupal 7 version
This is the best approach while migrating older Drupal 7 version to Drupal 8. Because for running migrate modules smoothly we need to ensure core files and database tables are latest.
Prepare catalog of Current Drupal 7 Website
Before migration starts we have to list out components in current websites, this will be helpful in moving forward. Keep an excel sheet or any comfortable document where list out all content types , modules , views,taxonomy , custom blocks etc.
there is no migration path for view configurations. so list out all views which currently using , this need to be manually created during migration.
Install fresh Drupal 8 from drupal.org
download and install latest Drupal 8 version from drupal.org.
List of contributed modules installed
Prepare list of contributed module list in existing website(Drupal 7). We have to check for each contributed modules Drupal 8 version is available or not. Most of the major modules have corresponding production ready Drupal 8 version available. But for some modules it will be in alpha or beta stage. Some contributed modules are now part of Drupal core. Also modules may not be available in Drupal 8. For modules are not available in Drupal 8 we have to analyse for which functionality it is using and install alternate module in Drupal 8 that will do same functionality. If it is not available create custom module which will do same functionality. But most of the modules are available in Drupal 8.
Below is the some major modules which is already available in Drupal Core.
Views , CKeditor etc
install all available modules in new Drupal 8 instance. Then only corresponding module contents migrated during migration process.
Install Essential modules
Enable Update manager module to install new modules in new instance. You can message to enable this module while opening extent menu.
enable Update manager module and then click configure link
This will open window where yu can install new contributed modules.
Before going to enable migrate module. we are installing Admin tool bar module which will show admin menu as below picture. This module will help to traverse to all pages from top toolbar.
install this module from below link
https://www.drupal.org/project/admin_toolbar
Also you can use below module for better admin menu
https://www.drupal.org/project/adminimal_admin_toolbar
Enable migrate modules
after installation go to list modules in extent menu.
You can see below migrate modules. enable those modules.
Conclusion
Now we prepared new Drupal 8 server with all contributed modules installed. Next we are going for migration of Drupal 7 to Drupal 8.
Read How to estimate Drupal 7 to Drupal 8 Migration