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Viktor Barzin 01a718e17b [mailserver] Filter redundant local→local aliases to fix Dovecot 'exists more than once'
## Context

Dovecot auth logs have been steadily spamming
`passwd-file /etc/dovecot/userdb: User r730-idrac@viktorbarzin.me exists more
than once` (and the same for vaultwarden@) at ~31 occurrences per 500 log
lines. Under load this flakes IMAP auth for the e2e email-roundtrip probe
(spam@viktorbarzin.me uses the catch-all), which was masquerading as "Brevo
or probe timing" noise.

## Root cause

docker-mailserver builds Dovecot's `/etc/dovecot/userdb` from two sources:
real accounts (`postfix-accounts.cf`) AND virtual-alias entries whose
*target* resolves to a local mailbox (`postfix-virtual.cf`). When the same
address appears as BOTH a real mailbox AND an alias whose target is another
local mailbox, the generated userdb has two lines for that username pointing
to different home directories — e.g.:

  r730-idrac@viktorbarzin.me:...:/var/mail/.../r730-idrac/home
  r730-idrac@viktorbarzin.me:...:/var/mail/.../spam/home      ← from alias

Dovecot's passwd-file driver rejects the duplicate, and every subsequent
auth lookup logs the error.

This affected exactly two addresses:
- r730-idrac@viktorbarzin.me (real account + alias → spam@)
- vaultwarden@viktorbarzin.me  (real account + alias → me@)

Other aliases are fine: they either forward to external addresses (gmail
etc.) — no local userdb entry generated — or map an address to itself
(me@ → me@) which docker-mailserver dedups internally.

Note: removing the real accounts is not an option because Vaultwarden uses
`vaultwarden@viktorbarzin.me` as its live SMTP_USERNAME
(stacks/vaultwarden/modules/vaultwarden/main.tf:121).

## This change

Introduces a `local.postfix_virtual` that concatenates the Vault-sourced
aliases with `extra/aliases.txt`, then filters out any line matching the
exact "LHS RHS" shape where both sides are in `var.mailserver_accounts` and
LHS != RHS. That is, only the pure local→local redundant entries are
dropped; all forwarding aliases and the catch-all are preserved.

The filter is self-healing: if a future alias ever collides with a real
account, it gets silently suppressed instead of breaking Dovecot auth.

```
  Vault mailserver_aliases  ─┐
                              ├─ concat ─ split \n ─ filter ─ join \n ─► postfix-virtual.cf
  extra/aliases.txt ─────────┘                        │
                                                       └── drop if LHS+RHS both in
                                                           mailserver_accounts and
                                                           LHS != RHS
```

Filtered entries (confirmed via locally-simulated filter on live data):
- r730-idrac@viktorbarzin.me spam@viktorbarzin.me
- vaultwarden@viktorbarzin.me me@viktorbarzin.me

Preserved (sample): postmaster→me, contact→me, alarm-valchedrym→self+3 ext,
lubohristov→gmail, yoana→gmail, @viktorbarzin.me→spam (catch-all), all four
disposable `*-generated@` aliases.

## What is NOT in this change

- Real accounts in Vault (`secret/platform.mailserver_accounts`) are
  untouched — vaultwarden SMTP auth keeps working.
- Postfix postscreen btree lock contention (separate commit).
- Email-roundtrip probe IMAP window (separate commit).

## Test Plan

### Automated

`terraform validate` — passes (docker-mailserver module):

```
Success! The configuration is valid, but there were some validation warnings as shown above.
```

`scripts/tg plan -target=module.mailserver.kubernetes_config_map.mailserver_config`:

```
  # module.mailserver.kubernetes_config_map.mailserver_config will be updated in-place
  ~ resource "kubernetes_config_map" "mailserver_config" {
      ~ data = {
          ~ "postfix-virtual.cf" = (sensitive value)
            # (9 unchanged elements hidden)
        }
        id = "mailserver/mailserver.config"
    }
Plan: 0 to add, 1 to change, 0 to destroy.
```

`scripts/tg apply` — applied:

```
Apply complete! Resources: 0 added, 1 changed, 0 destroyed.
```

### Manual Verification

Post-apply configmap content (the two lines are gone):

```
$ kubectl -n mailserver get cm mailserver.config -o jsonpath='{.data.postfix-virtual\.cf}'
postmaster@viktorbarzin.me me@viktorbarzin.me
contact@viktorbarzin.me me@viktorbarzin.me
me@viktorbarzin.me me@viktorbarzin.me
lubohristov@viktorbarzin.me lyubomir.hristov3@gmail.com
alarm-valchedrym@viktorbarzin.me alarm-valchedrym@...,vbarzin@...,emil.barzin@...,me@...
yoana@viktorbarzin.me divcheva.yoana@gmail.com

@viktorbarzin.me spam@viktorbarzin.me
firmly-gerardo-generated@viktorbarzin.me me@viktorbarzin.me
closely-keith-generated@viktorbarzin.me vbarzin@gmail.com
literally-paolo-generated@viktorbarzin.me viktorbarzin@fb.com
hastily-stefanie-generated@viktorbarzin.me elliestamenova@gmail.com
```

Reloader triggers a pod rollout; once new pod is Ready:
- `kubectl -n mailserver exec <pod> -c docker-mailserver -- cut -d: -f1 /etc/dovecot/userdb | sort | uniq -d`
  expected output: empty (no duplicate usernames)
- `kubectl -n mailserver logs <pod> -c docker-mailserver --tail=500 | grep -c "exists more than once"`
  expected output: 0 (baseline was 31/500 lines)

## Reproduce locally

1. `kubectl -n mailserver get cm mailserver.config -o jsonpath='{.data.postfix-virtual\.cf}'`
2. Expect: no `r730-idrac@viktorbarzin.me spam@viktorbarzin.me` line and no
   `vaultwarden@viktorbarzin.me me@viktorbarzin.me` line.
3. After pod restart: `kubectl -n mailserver logs -l app=mailserver -c docker-mailserver --tail=500 | grep -c "exists more than once"` → 0.

Closes: code-27l

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
2026-04-18 21:29:02 +00:00
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This repo contains my infra-as-code sources.

My infrastructure is built using Terraform, Kubernetes and CI/CD is done using Woodpecker CI.

Read more by visiting my website: https://viktorbarzin.me

Documentation

Full architecture documentation is available in docs/ — covering networking, storage, security, monitoring, secrets, CI/CD, databases, and more.

Adding a New User (Admin)

Adding a new namespace-owner to the cluster requires three steps — no code changes needed.

1. Authentik Group Assignment

In the Authentik admin UI, add the user to:

  • kubernetes-namespace-owners group (grants OIDC group claim for K8s RBAC)
  • Headscale Users group (if they need VPN access)

2. Vault KV Entry

Add a JSON entry to secret/platformk8s_users key in Vault:

"username": {
  "role": "namespace-owner",
  "email": "user@example.com",
  "namespaces": ["username"],
  "domains": ["myapp"],
  "quota": {
    "cpu_requests": "2",
    "memory_requests": "4Gi",
    "memory_limits": "8Gi",
    "pods": "20"
  }
}
  • username key must match the user's Forgejo username (for Woodpecker admin access)
  • namespaces — K8s namespaces to create and grant admin access to
  • domains — subdomains under viktorbarzin.me for Cloudflare DNS records
  • quota — resource limits per namespace (defaults shown above)

3. Apply Stacks

vault login -method=oidc

cd stacks/vault && terragrunt apply --non-interactive
# Creates: namespace, Vault policy, identity entity, K8s deployer role

cd ../platform && terragrunt apply --non-interactive
# Creates: RBAC bindings, ResourceQuota, TLS secret, DNS records

cd ../woodpecker && terragrunt apply --non-interactive
# Adds user to Woodpecker admin list

What Gets Auto-Generated

Resource Stack
Kubernetes namespace vault
Vault policy (namespace-owner-{user}) vault
Vault identity entity + OIDC alias vault
K8s deployer Role + Vault K8s role vault
RBAC RoleBinding (namespace admin) platform
RBAC ClusterRoleBinding (cluster read-only) platform
ResourceQuota platform
TLS secret in namespace platform
Cloudflare DNS records platform
Woodpecker admin access woodpecker

New User Onboarding

If you've been added as a namespace-owner, follow these steps to get started.

1. Join the VPN

# Install Tailscale: https://tailscale.com/download
tailscale login --login-server https://headscale.viktorbarzin.me
# Send the registration URL to Viktor, wait for approval
ping 10.0.20.100  # verify connectivity

2. Install Tools

Run the setup script to install kubectl, kubelogin, Vault CLI, Terraform, and Terragrunt:

# macOS
bash <(curl -fsSL https://k8s-portal.viktorbarzin.me/setup/script?os=mac)

# Linux
bash <(curl -fsSL https://k8s-portal.viktorbarzin.me/setup/script?os=linux)

3. Authenticate

# Log into Vault (opens browser for SSO)
vault login -method=oidc

# Test kubectl (opens browser for OIDC login)
kubectl get pods -n YOUR_NAMESPACE

4. Deploy Your First App

# Clone the infra repo
git clone https://github.com/ViktorBarzin/infra.git && cd infra

# Copy the stack template
cp -r stacks/_template stacks/myapp
mv stacks/myapp/main.tf.example stacks/myapp/main.tf

# Edit main.tf — replace all <placeholders>

# Store secrets in Vault
vault kv put secret/YOUR_USERNAME/myapp DB_PASSWORD=secret123

# Submit a PR
git checkout -b feat/myapp
git add stacks/myapp/
git commit -m "add myapp stack"
git push -u origin feat/myapp

After review and merge, an admin runs cd stacks/myapp && terragrunt apply.

5. Set Up CI/CD (Optional)

Create .woodpecker.yml in your app's Forgejo repo:

steps:
  - name: build
    image: woodpeckerci/plugin-docker-buildx
    settings:
      repo: YOUR_DOCKERHUB_USER/myapp
      tag: ["${CI_PIPELINE_NUMBER}", "latest"]
      username:
        from_secret: dockerhub-username
      password:
        from_secret: dockerhub-token
      platforms: linux/amd64

  - name: deploy
    image: hashicorp/vault:1.18.1
    commands:
      - export VAULT_ADDR=http://vault-active.vault.svc.cluster.local:8200
      - export VAULT_TOKEN=$(vault write -field=token auth/kubernetes/login
          role=ci jwt=$(cat /var/run/secrets/kubernetes.io/serviceaccount/token))
      - KUBE_TOKEN=$(vault write -field=service_account_token
          kubernetes/creds/YOUR_NAMESPACE-deployer
          kubernetes_namespace=YOUR_NAMESPACE)
      - kubectl --server=https://kubernetes.default.svc
          --token=$KUBE_TOKEN
          --certificate-authority=/var/run/secrets/kubernetes.io/serviceaccount/ca.crt
          -n YOUR_NAMESPACE set image deployment/myapp
          myapp=YOUR_DOCKERHUB_USER/myapp:${CI_PIPELINE_NUMBER}

Useful Commands

# Check your pods
kubectl get pods -n YOUR_NAMESPACE

# View quota usage
kubectl describe resourcequota -n YOUR_NAMESPACE

# Store/read secrets
vault kv put secret/YOUR_USERNAME/myapp KEY=value
vault kv get secret/YOUR_USERNAME/myapp

# Get a short-lived K8s deploy token
vault write kubernetes/creds/YOUR_NAMESPACE-deployer \
  kubernetes_namespace=YOUR_NAMESPACE

Important Rules

  • All changes go through Terraform — never kubectl apply/edit/patch directly
  • Never put secrets in code — use Vault: vault kv put secret/YOUR_USERNAME/...
  • Always use a PR — never push directly to master
  • Docker images: build for linux/amd64, use versioned tags (not :latest)

git-crypt setup

To decrypt the secrets, you need to setup git-crypt.

  1. Install git-crypt.
  2. Setup gpg keys on the machine
  3. git-crypt unlock

This will unlock the secrets and will lock them on commit