https://github.com/systemli/userli-postfix-adapter
https://github.com/systemli/userli-postfix-adapter
Last synced: about 1 month ago
JSON representation
- Host: GitHub
- URL: https://github.com/systemli/userli-postfix-adapter
- Owner: systemli
- License: gpl-3.0
- Created: 2024-09-29T11:24:48.000Z (over 1 year ago)
- Default Branch: main
- Last Pushed: 2026-04-22T14:32:02.000Z (about 2 months ago)
- Last Synced: 2026-04-22T16:27:08.057Z (about 2 months ago)
- Language: Go
- Size: 202 KB
- Stars: 0
- Watchers: 3
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- License: LICENSE
- Codeowners: .github/CODEOWNERS
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README
# userli-postfix-adapter
[](https://github.com/systemli/userli-postfix-adapter/actions/workflows/integration.yml) [](https://sonarcloud.io/summary/new_code?id=systemli_userli-postfix-adapter) [](https://sonarcloud.io/summary/new_code?id=systemli_userli-postfix-adapter) [](https://sonarcloud.io/summary/new_code?id=systemli_userli-postfix-adapter)
This is a postfix socketmap adapter for the [userli](https://github.com/systemli/userli) project.
It implements the [socketmap protocol](https://www.postfix.org/socketmap_table.5.html) to provide dynamic lookups for aliases, domains, mailboxes, and senders.
## Configuration
The adapter is configured via environment variables:
- `USERLI_TOKEN`: The token to authenticate against the userli API.
- `USERLI_BASE_URL`: The base URL of the userli API.
- `POSTFIX_RECIPIENT_DELIMITER`: The recipient delimiter used in Postfix (e.g., `+`). Default: empty.
- `SOCKETMAP_LISTEN_ADDR`: The address to listen on for socketmap requests. Default: `:10001`.
- `POLICY_LISTEN_ADDR`: The address to listen on for policy requests (rate limiting). Default: `:10003`.
- `METRICS_LISTEN_ADDR`: The address to listen on for metrics. Default: `:10002`.
- `RATE_LIMIT_MESSAGE`: The rejection message returned when a sender exceeds their quota. Default: `Rate limit exceeded, please try again later`.
- `REDIS_URL`: Connection URL for Redis (required). Format follows [`redis.ParseURL`](https://pkg.go.dev/github.com/redis/go-redis/v9#ParseURL), e.g. `redis://[user:password@]host:port/db`. Rate-limit state is stored in Redis so it survives restarts.
- `LOOKUP_CACHE_TTL`: TTL for cached successful (`OK`) lookup responses in Redis. Accepts any [Go duration](https://pkg.go.dev/time#ParseDuration) (e.g. `300s`, `5m`). Default: `300s`. Set to `0` to disable the cache. `NOTFOUND`/`TEMP`/`PERM` responses are never cached.
In Postfix, you can configure the adapter using the socketmap protocol like this:
```text
virtual_alias_maps = socketmap:inet:localhost:10001:alias
virtual_mailbox_domains = socketmap:inet:localhost:10001:domain
virtual_mailbox_maps = socketmap:inet:localhost:10001:mailbox
smtpd_sender_login_maps = socketmap:inet:localhost:10001:senders
```
### Rate Limiting (Policy Server)
The adapter also provides a Postfix SMTP Access Policy Delegation server for rate limiting outgoing mail.
It queries the Userli API for per-user quotas and enforces sending limits.
Configure in Postfix `main.cf`:
```text
smtpd_end_of_data_restrictions = check_policy_service inet:localhost:10003
```
The Userli API endpoint `/api/postfix/smtp_quota/{email}` returns:
```json
{
"per_hour": 100,
"per_day": 1000
}
```
Where `0` means unlimited. If the API is unreachable, messages are allowed (fail-open).
Rate-limit state is persisted to Redis (`REDIS_URL`) so it survives restarts. If Redis is unreachable, messages are also allowed (fail-open) and the `userli_postfix_adapter_ratelimit_backend_errors_total` counter is incremented.
## Docker
You can run the adapter using Docker.
A `docker-compose.yml` file is provided for convenience.
```bash
docker compose up -d
# Create the database and load fixtures
docker compose exec userli bin/console doctrine:schema:create
docker compose exec userli bin/console doctrine:fixtures:load --no-debug
docker compose exec postfix postmap -q "example.org" socketmap:inet:adapter:10001:domain
```
The socketmap names supported are:
- `alias` - For virtual alias lookups
- `domain` - For virtual domain lookups
- `mailbox` - For virtual mailbox lookups
- `senders` - For sender login map lookups
## Usage Example
You can test the socketmap adapter using `postmap`:
```bash
# Test alias lookup
postmap -q "test@example.com" socketmap:inet:localhost:10001:alias
# Test domain lookup
postmap -q "example.com" socketmap:inet:localhost:10001:domain
# Test mailbox lookup
postmap -q "user@example.com" socketmap:inet:localhost:10001:mailbox
# Test sender lookup
postmap -q "sender@example.com" socketmap:inet:localhost:10001:senders
```
### Docker Usage
```bash
# Build and run with docker-compose
docker-compose up --build
# Or build manually
docker build -t userli-postfix-adapter .
docker run -e USERLI_TOKEN=your_token -e USERLI_BASE_URL=http://your-userli-instance -p 10001:10001 -p 10002:10002 userli-postfix-adapter
```
## Protocol Details
The adapter implements the Postfix socketmap protocol using netstrings for encoding. Each request and response is formatted as:
```text
[length]:[data],
```
Where:
- `length` is the decimal length of the data
- `:` is a delimiter
- `data` is the actual request or response content
- `,` is the terminating comma
### Request Format
```text
[length]:[mapname key],
```
Examples:
- `22:alias test@example.com,` - Look up alias for
- `18:domain example.com,` - Check if domain example.com exists
- `23:mailbox user@example.com,` - Check if mailbox exists
- `24:senders user@example.com,` - Get senders for
### Response Format
The adapter returns one of these response types:
- `OK [data]` - Successful lookup with data
- `NOTFOUND` - No data found for the key
- `TEMP [reason]` - Temporary error (retry later)
- `PERM [reason]` - Permanent error (don't retry)
Examples:
- `19:OK dest@example.com,` - Alias found, destination is
- `4:OK 1,` - Domain/mailbox exists
- `8:NOTFOUND,` - No data found
- `20:TEMP Service error,` - Temporary service error
## Observability
The adapter exposes Prometheus metrics on `/metrics` (port 10002) and provides health check endpoints.
### Metrics
**Socketmap Metrics:**
- `userli_postfix_adapter_request_duration_seconds` - Request duration histogram
- `userli_postfix_adapter_requests_total` - Total request counter
- `userli_postfix_adapter_active_connections` - Active connections gauge
- `userli_postfix_adapter_connection_pool_usage` - Connection pool usage (0-500)
**HTTP Client Metrics:**
- `userli_postfix_adapter_http_client_duration_seconds` - Userli API request duration
- `userli_postfix_adapter_http_client_requests_total` - Userli API request counter
**Health:**
- `userli_postfix_adapter_health_check_status` - Health check status (1=healthy, 0=unhealthy)
**Policy/Rate Limiting Metrics:**
- `userli_postfix_adapter_policy_active_connections` - Active policy connections gauge
- `userli_postfix_adapter_policy_requests_total` - Total policy request counter
- `userli_postfix_adapter_policy_request_duration_seconds` - Policy request duration histogram
- `userli_postfix_adapter_quota_exceeded_total` - Total messages rejected due to quota
- `userli_postfix_adapter_quota_checks_total` - Total quota checks performed
- `userli_postfix_adapter_ratelimit_backend_errors_total` - Total Redis errors hit by the rate limiter, labelled by `operation`
All metrics include relevant labels (handler, status, endpoint, etc.).
### Health Endpoints
- **`/health`** - Liveness probe (always returns 200 OK)
- **`/ready`** - Readiness probe (checks Userli API connectivity)
Example Kubernetes configuration:
```yaml
livenessProbe:
httpGet:
path: /health
port: 10002
readinessProbe:
httpGet:
path: /ready
port: 10002
```