How to Install new module, add code to existing module that requires the new module, and import config for the new module in the same build

Question

I seem to be running into a circular dependency issue in the scenario where my new build has a new module (B), new code in an existing module (A) that depends on the new module (B) and new config being imported for the new module (B).

In the past I have handled this with creating and deploying two independent builds, one where I deploy the new modules and enable them, and in the second build, deploy code that requires the new modules and the config for the new modules.

Is there a better way to handle this?

The change in Module A is that one of the services in Module A requires a service from Module B.

I have already added dependency to the new module B in module_A.info.yml file but that does not help as the module is already installed.

drush en module_b does not work and it gives the error.

The service "module_A_service" has a dependency on a non-existent service "module_B_service".

The config import that is in the build has core.extensions updated to enable module_B when it is imported but config import with drush cim is failing with the same error as above.

Answer 1

This is the solution that worked

a) Implement a hook_update_N in module A that is already installed. In the hook_update_N add code to install module_b. Include this in the same build.

function module_a_update_NNNN(&$sandbox) {
  $module_installer = \Drupal::service('module_installer');
  $module_handler = \Drupal::service('module_handler');
  if (!$module_handler->moduleExists('module_b')) {
    $module_installer->install(['module_b']);
  }
}

b) Deploy the build

c) Do not clear cache. If you run cache clear before updb it will throw the same error as mentioned in the question.

d) Run drush updb

e) Run drush cim

f) Run drush cr