[GitHub] [james-project] quantranhong1999 commented on a diff in pull request #1489: [ADR] Changing username

["quantranhong1999 (via GitHub)" <gi...@apache.org>]

quantranhong1999 commented on code in PR #1489:
URL: https://github.com/apache/james-project/pull/1489#discussion_r1139775150


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src/adr/0065-changing-username.md:
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+# 65. Changing username
+
+Date: 2023-03-17
+
+## Status
+
+Accepted (lazy consensus).
+
+Implemented.
+
+## Context
+Changing username is a desired feature for an email server. It is a common practice when a user marries. For example: 
+
+Alice MARTINEZ have an email address `alice.martinez@domain.tld` and gets married to Bob ERNANDEZ. She thus wants to
+change her email address to `alice.ernandez@domain.tld` while preserving her email data.
+
+Nowadays, James uses username as an identifier for user data. Therefore, this feature is hard to implement because of changing 
+directly identifier to another value is difficult and could break data consistency if we do not do it carefully.
+
+## Decision
+
+Need to copy the data
+Modular design
+
+We decided to do changing username with two steps: first create new username, then migrate the old user's data to new account - 
+the way we expect that is less dangerous to current data consistency. The data in old account need to be truncated after migrated to new account.
+
+For the data migration step, we decided to form it under a webadmin task with a modular design. A big data migration task contains 
+many small tasks that implement `UsernameChangeTaskStep` interface. This modular design for migration steps could help developers easier 
+to manage/test each step, and help other tailor James servers can implement their own steps as well.
+
+Today, implemented migration steps are:
+
+- `ForwardUsernameChangeTaskStep`: creates forward from old user to new user and migrates existing forwards
+- `FilterUsernameChangeTaskStep`: migrates users filtering rules
+- `DelegationUsernameChangeTaskStep`: migrates delegations where the impacted user is either delegatee or delegator
+- `MailboxUsernameChangeTaskStep`: migrates mailboxes belonging to the old user to the account of the new user. It also
+  migrates user's mailbox subscriptions.
+- `ACLUsernameChangeTaskStep`: migrates ACLs on mailboxes the migrated user has access to and updates subscriptions accordingly.
+
+We introduce `fromStep` query parameter that allows skipping previous steps, allowing to resume the username change from a failed step.
+This option could ease operators in case the data migration fails in the middle.
+
+## Consequences
+- Add one more useful feature to James rich feature set: Users can change their name while preserving their email data.
+- User would be aware that they have a new account through new username/password. No implicit migration without user attention is archived today.
+- JMAP Identity data is not migrated because they are tightly coupled to old username, user should create identities again themselves.
+- Some data considered not critical like Push subscription, Vacation response,... are not migrated today. Contributions for them is welcome.

Review Comment:
   BTW are we missing migration for Quota?



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