SurrealDB

Build services on SurrealDB, the multi-model database. One URL scheme selects the protocol at runtime - embed it in-process for tests, point at a server in production.

Overview

acton-service provides SurrealDB integration with:

• Runtime protocol selection - the any engine picks the transport from the URL scheme
• Automatic retry logic - exponential backoff for connection failures
• Actor-based management - connection lifecycle handled by SurrealDbAgent
• Root authentication - optional username/password signin
• Health monitoring - reported through the readiness probe
• Append-only audit storage - SurrealDB is a supported audit backend

The client type is SurrealClient, an alias for surrealdb::Surreal<surrealdb::engine::any::Any>.

Installation

Enable the surrealdb feature:

[dependencies]
acton-service = { version = "0.31.1", features = ["surrealdb"] }

Or add it to an existing feature set:

[dependencies]
acton-service = { version = "0.31.1", features = ["http", "surrealdb", "observability"] }

Connection Modes

The URL scheme determines the transport - there is no separate mode setting:

# In-memory, no server required
[surrealdb]
url = "mem://"

# WebSocket against a running SurrealDB server
[surrealdb]
url = "ws://localhost:8000"
username = "root"
password = "root"

Configuration

Full configuration options:

# config.toml
[surrealdb]
# Connection URL - the scheme selects the protocol (required)
url = "ws://localhost:8000"

# Namespace to use (default: "default")
namespace = "myapp"

# Database to use (default: "default")
database = "production"

# Root username for authentication (optional)
username = "root"

# Root password for authentication (optional)
password = "root"

# Maximum retry attempts for the connection (default: 5)
max_retries = 5

# Delay between retry attempts in seconds (default: 2)
retry_delay_secs = 2

# Whether the database is optional (default: false)
# If true, the service can start without a SurrealDB connection
optional = false

# Lazy initialization (default: true)
# If true, the connection is established in the background after startup
lazy_init = true

Authentication is only attempted when both username and password are set; the client signs in as a root user, then selects the configured namespace and database. Retries use exponential backoff, doubling retry_delay_secs on each attempt up to max_retries.

Environment Variable Overrides

ACTON_SURREALDB_URL=ws://surreal.prod.example.com:8000
ACTON_SURREALDB_NAMESPACE=myapp
ACTON_SURREALDB_DATABASE=production

# Pull the password from a secrets manager in production
export ACTON_SURREALDB_PASSWORD=$(vault read -field=password secret/surrealdb)

Basic Usage

Access SurrealDB through AppState. state.surrealdb() is async and returns Option<Arc<SurrealClient>> - it is None when SurrealDB is not configured or not yet connected.

use acton_service::prelude::*;

#[derive(Debug, Serialize, Deserialize)]
struct User {
    name: String,
    email: String,
}

async fn list_users(
    State(state): State<AppState>,
) -> Result<Json<Vec<User>>> {
    let db = state
        .surrealdb()
        .await
        .ok_or_else(|| Error::Internal("SurrealDB not available".into()))?;

    let users: Vec<User> = db
        .query("SELECT name, email FROM users ORDER BY name")
        .await?
        .take(0)?;

    Ok(Json(users))
}

surrealdb::Error converts into the framework's Error::Database(DatabaseError) automatically, so a bare ? works inside handlers.

Parameterized Queries

Bind parameters instead of interpolating them into SurrealQL:

async fn find_user(
    State(state): State<AppState>,
    Path(email): Path<String>,
) -> Result<Json<Option<User>>> {
    let db = state
        .surrealdb()
        .await
        .ok_or_else(|| Error::Internal("SurrealDB not available".into()))?;

    let user: Option<User> = db
        .query("SELECT name, email FROM users WHERE email = $email LIMIT 1")
        .bind(("email", email))
        .await?
        .take(0)?;

    Ok(Json(user))
}

Creating Records

async fn create_user(
    State(state): State<AppState>,
    Json(input): Json<User>,
) -> Result<Json<User>> {
    let db = state
        .surrealdb()
        .await
        .ok_or_else(|| Error::Internal("SurrealDB not available".into()))?;

    let created: Option<User> = db
        .query("CREATE users CONTENT $data")
        .bind(("data", input))
        .await?
        .take(0)?;

    created
        .map(Json)
        .ok_or_else(|| Error::Internal("Insert returned no record".into()))
}

take(n) selects the result set of the nth statement, so a multi-statement query() can be unpacked one statement at a time.

Health Checks

SurrealDB health is reported through SurrealDbHealth in the pool health summary, which backs the /ready endpoint. It carries the sanitized URL (credentials stripped), the namespace, the database, and whether the client is connected.

[surrealdb]
optional = false  # Service is not ready until SurrealDB connects

curl http://localhost:8080/ready
# Returns 200 OK if SurrealDB is healthy
# Returns 503 Service Unavailable if it is down

Set optional = true to let the service stay ready while SurrealDB is unavailable - state.surrealdb() simply returns None, and handlers decide how to degrade.

Audit Storage

With the audit and surrealdb features enabled, SurrealDB is a supported append-only audit backend. The audit_events table is defined with immutability enforced at the database level:

DEFINE TABLE IF NOT EXISTS audit_events SCHEMAFUL
    PERMISSIONS
        FOR select FULL
        FOR create FULL
        FOR update NONE
        FOR delete NONE;

Update and delete are denied by the database itself, so the hash-chained audit log cannot be rewritten through the application. See Audit Logging for the event model and configuration.

Error Handling

Connection errors are categorized with troubleshooting guidance attached to the message:

• Authentication errors - bad credentials or a user without permission to sign in
• Network errors - the server is unreachable, DNS fails, or the connection is refused
• Permission errors - the user cannot access the requested namespace or database
• Not found errors - the namespace or database does not exist
• Timeout errors - the server is overloaded or unresponsive

URLs are sanitized before logging, so credentials embedded in a connection URL are never written to logs.

Testing with mem://

The in-memory engine needs no server, which makes it a good fit for integration tests:

# config.test.toml
[surrealdb]
url = "mem://"
namespace = "test"
database = "test"
lazy_init = false  # Connect during startup so tests fail fast

Related Features

• Database (PostgreSQL) - PostgreSQL integration (mutually exclusive with surrealdb)
• Turso (libsql) - Edge SQLite integration (mutually exclusive with surrealdb)
• ClickHouse (Analytics) - Analytical store that composes with any primary backend
• Audit Logging - Append-only audit events with SurrealDB storage
• Health Checks - Automatic database health monitoring
• Reactive Architecture - Actor-based connection management