SLT-1103: Drupal chart: Add support for mailpit, deprecate mailhog

[k4lv15]

Motivation:
Mailhog is an email service we’re using in our development environments (local & Silta non-production) to test out if email functionalities are working properly. Mailhog is not maintained anymore and is causing issues for developers. Therefore, we need to replace it with some alternative. Our current pick is Mailpit.

Changes proposed:

• Add mailpit dependency, enable it, add default value overrides
• Update chart templates with needed changes for mailpit to work
• Update unit tests to run against mailpit instead of mailhog
• Keep mailhog in chart but add deprecation notices

How to test:

1. Install the updated chart and see that mailpit works (helm install drupal-release charts/drupal --set mailpit.enabled=true or test here: https://app.circleci.com/pipelines/github/wunderio/drupal-project-k8s/6873/workflows/20d2da53-257e-4bc2-8d2e-85bbb7c3eae2/jobs/22713). Test the following:
   • validation goes through (i.e., unit tests pass: helm unittest ./charts/drupal)
   • mailpit URL is listed in the release notes and it works
   • the legacy /mailhog path redirects to /mailpit
   • emails sent from Drupal (i.e., after password reset or new account creation) end up in mailpit, mailpit's UI works, i.e, you can mark emails as read, delete them, download etc.
2. See that updated installation checks work, i.e., try to install chart with both mailpit and mailhog enabled, see that the installation fails (or see screenshot below)
   

[Copilot]

Pull Request Overview

This pull request replaces Mailhog with Mailpit in the Drupal chart to address maintenance concerns and ensure a stable email testing service in development environments. Key changes include:

• Adding Mailpit configuration and dependency while deprecating Mailhog.
• Updating chart templates, tests, and configuration files to support Mailpit.
• Adding validation rules to prevent dual activation and production use of deprecated services.

Reviewed Changes

Copilot reviewed 11 out of 14 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
silta/silta.yml	Added Mailpit service flag
charts/drupal/values.yaml	Introduced Mailpit configuration values and overrides
charts/drupal/tests/drupal_deployment_test.yaml	Updated test cases to refer to Mailpit
charts/drupal/test.values.yaml	Changed Mailhog to Mailpit in test values
charts/drupal/templates/varnish-configmap-vcl.yaml	Added proxy bypass for Mailpit URLs
charts/drupal/templates/smtp-secret.yaml	Modified condition to include Mailpit
charts/drupal/templates/drupal-configmap.yaml	Added redirect from legacy Mailhog to Mailpit
charts/drupal/templates/checks.yaml	Inserted checks to prevent enabling both services simultaneously and blocking deprecated usage in production
charts/drupal/Chart.yaml	Added Mailpit as a chart dependency
.circleci/config.yml	Added Helm repo for the new Mailpit chart dependency

Files not reviewed (3)

• charts/drupal/templates/NOTES.txt: Language not supported
• charts/drupal/templates/_helpers.tpl: Language not supported
• charts/drupal/values.schema.json: Language not supported

Comments suppressed due to low confidence (1)

charts/drupal/values.yaml:757

• [nitpick] The nested 'mailpit' key inside the main Mailpit configuration block may be confusing. Consider renaming it (e.g., to 'webrootConfig' or similar) for clearer structure.

  mailpit:

[tormi]

RTBC. Nice work, thanks @k4lv15 ! 👍

/var/www/html$ env | grep SMTP_ADDRESS
SMTP_ADDRESS=feature-slt-1103-mail-mailpit-smtp:25