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mrhid6andClaude Opus 5 da3afca7fa feat(shared): unique users index is (instance_id, email)
One address is one user within an instance, not globally, so an account's
people can be projected into every instance they are granted.

The replacement index is created before email_1 is dropped, so a failure
at any point leaves a working constraint. The drop is idempotent and
tolerates two services racing it.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
2026-07-26 12:48:27 +01:00

100 lines
3.3 KiB
Go

// Package indexes declares the MongoDB indexes more than one Vantage service
// depends on.
package indexes
import (
"context"
"errors"
"fmt"
"go.mongodb.org/mongo-driver/v2/bson"
"go.mongodb.org/mongo-driver/v2/mongo"
"go.mongodb.org/mongo-driver/v2/mongo/options"
)
// legacyUserEmailIndex is the global unique index on users.email that this
// package used to declare. It is dropped on sight.
const legacyUserEmailIndex = "email_1"
// indexNotFound is MongoDB's IndexNotFound error code. Two services booting at
// once can both decide to drop the legacy index; the loser must not treat that
// as a failure.
const indexNotFound = 27
// EnsureCoreIndexes declares the unique indexes on users and instances.
//
// users is unique on (instance_id, email), NOT on email alone. One address is
// one user WITHIN an instance; the same address may hold a user in several
// instances, because an account's people are projected into each instance they
// are granted access to.
//
// This is a security property, not an optimisation, and it is only sufficient
// because every lookup by email is scoped by instance. There is deliberately no
// unscoped lookup by email anywhere in the codebase: an unscoped FindOne would
// return an arbitrary one of several matching users, which on the login path
// means signing someone into a tenant that is not theirs. If you are about to
// add one, you are about to reintroduce that bug.
//
// Creating an index that already exists with the same specification is a no-op,
// so this is safe to call at every boot from every service.
func EnsureCoreIndexes(ctx context.Context, db *mongo.Database) error {
// Create the replacement BEFORE dropping the legacy index. A failure here
// leaves the old constraint in place, which is safe; a failure after the
// drop would leave the collection unconstrained, which is not.
if _, err := db.Collection("users").Indexes().CreateOne(ctx, mongo.IndexModel{
Keys: bson.D{{Key: "instance_id", Value: 1}, {Key: "email", Value: 1}},
Options: options.Index().SetUnique(true).SetName("instance_email_unique"),
}); err != nil {
return fmt.Errorf("users.instance_id+email index: %w", err)
}
if err := dropIndexIfExists(ctx, db.Collection("users"), legacyUserEmailIndex); err != nil {
return fmt.Errorf("drop users.%s: %w", legacyUserEmailIndex, err)
}
if _, err := db.Collection("instances").Indexes().CreateOne(ctx, mongo.IndexModel{
Keys: bson.D{{Key: "slug", Value: 1}},
Options: options.Index().SetUnique(true),
}); err != nil {
return fmt.Errorf("instances.slug index: %w", err)
}
return nil
}
// dropIndexIfExists drops name, treating "it was not there" as success whether
// that is discovered by listing or by racing another service to the drop.
func dropIndexIfExists(ctx context.Context, col *mongo.Collection, name string) error {
cur, err := col.Indexes().List(ctx)
if err != nil {
return err
}
var existing []struct {
Name string `bson:"name"`
}
if err := cur.All(ctx, &existing); err != nil {
return err
}
found := false
for _, i := range existing {
if i.Name == name {
found = true
break
}
}
if !found {
return nil
}
err = col.Indexes().DropOne(ctx, name)
if err == nil {
return nil
}
var srvErr mongo.ServerError
if errors.As(err, &srvErr) && srvErr.HasErrorCode(indexNotFound) {
return nil
}
return err
}