Using a Guard

The ClsGuard can be also used set up the CLS context. While it is not a "guard" per-se, it's the second best place to set up the CLS context, since after a middleware, it is the first piece of code that the request hits.

To use it, pass its configuration to the guard property to the ClsModule.forRoot() options:

Automatically

Use mount: true

app.module.ts

@Module({
    imports: [
        ClsModule.forRoot({
            guard: { mount: true },
        }),
    ],
    // ...
})
export class AppModule {}

Manually

If you need any other guards to use the ClsService, it's preferable to mount ClsGuard manually as the first guard in the root module:

app.module.ts

@Module({
    imports: [
        ClsModule.forRoot({
            guard: { mount: false }
        }),
    ]
    providers: [
        {
            provide: APP_GUARD,
            useClass: ClsGuard,
        },
    ],
    // ...
})
export class AppModule {}

or mount it directly on the Controller/Resolver with

@UseGuards(ClsGuard);

caution

Please note: since the ClsGuard uses the AsyncLocalStorage#enterWith method, using the ClsGuard comes with some security considerations!