postrust-lambda 0.1.0

AWS Lambda adapter for Postrust
Documentation 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187

//! Postrust AWS Lambda handler.
//!
//! Deploys Postrust as an AWS Lambda function.

use lambda_http::{run, service_fn, Body, Error, Request, Response};
use sqlx::postgres::PgPoolOptions;
use sqlx::PgPool;
use std::sync::Arc;
use tokio::sync::{OnceCell, RwLock};
use tracing::{debug, error, info};

// Static pool for connection reuse across invocations
static POOL: OnceCell<PgPool> = OnceCell::const_new();
static SCHEMA_CACHE: OnceCell<Arc<RwLock<postrust_core::SchemaCache>>> = OnceCell::const_new();

#[tokio::main]
async fn main() -> Result<(), Error> {
    tracing_subscriber::fmt()
        .with_max_level(tracing::Level::INFO)
        .with_target(false)
        .without_time()
        .init();

    info!("Starting Postrust Lambda handler");

    run(service_fn(handler)).await
}

async fn handler(event: Request) -> Result<Response<Body>, Error> {
    let config = postrust_core::AppConfig::from_env();

    // Get or create pool
    let pool = POOL
        .get_or_init(|| async {
            info!("Creating database pool");
            PgPoolOptions::new()
                .max_connections(1) // Single connection for Lambda
                .connect(&config.db_uri)
                .await
                .expect("Failed to connect to database")
        })
        .await;

    // Get or create schema cache
    let schema_cache = SCHEMA_CACHE
        .get_or_init(|| async {
            info!("Loading schema cache");
            let cache = postrust_core::SchemaCache::load(pool, &config.db_schemas)
                .await
                .expect("Failed to load schema cache");
            Arc::new(RwLock::new(cache))
        })
        .await;

    // Process request
    match process_lambda_request(event, pool, schema_cache, &config).await {
        Ok(response) => Ok(response),
        Err(e) => {
            error!("Request error: {}", e);
            Ok(error_response(e))
        }
    }
}

async fn process_lambda_request(
    event: Request,
    pool: &PgPool,
    schema_cache: &Arc<RwLock<postrust_core::SchemaCache>>,
    config: &postrust_core::AppConfig,
) -> Result<Response<Body>, postrust_core::Error> {
    let jwt_config = postrust_auth::JwtConfig {
        secret: config.jwt_secret.clone(),
        secret_is_base64: config.jwt_secret_is_base64,
        audience: config.jwt_aud.clone(),
        role_claim_key: config.jwt_role_claim_key.clone(),
        anon_role: config.db_anon_role.clone(),
    };

    // Extract auth header
    let auth_header = event
        .headers()
        .get("authorization")
        .and_then(|v| v.to_str().ok());

    // Authenticate
    let auth_result = postrust_auth::authenticate(auth_header, &jwt_config)
        .map_err(|e| postrust_core::Error::InvalidJwt(e.to_string()))?;

    debug!("Authenticated as role: {}", auth_result.role);

    // Parse request body
    let body_bytes = match event.body() {
        Body::Empty => bytes::Bytes::new(),
        Body::Text(s) => bytes::Bytes::from(s.clone()),
        Body::Binary(b) => bytes::Bytes::from(b.clone()),
    };

    // Build HTTP request for parsing
    let mut builder = http::Request::builder()
        .method(event.method().clone())
        .uri(event.uri().clone());

    for (key, value) in event.headers() {
        builder = builder.header(key, value);
    }

    let http_request = builder
        .body(body_bytes.clone())
        .map_err(|e: http::Error| postrust_core::Error::Internal(e.to_string()))?;

    // Parse API request
    let mut api_request = postrust_core::parse_request(
        &http_request,
        config.default_schema(),
        &config.db_schemas,
    )?;

    // Parse payload
    if !body_bytes.is_empty() {
        let payload = postrust_core::api_request::payload::parse_payload(
            body_bytes,
            &api_request.content_media_type,
        )?;
        api_request.payload = payload;
    }

    // Get schema cache
    let cache = schema_cache.read().await;

    // Create execution plan
    let plan = postrust_core::create_action_plan(&api_request, &cache)?;

    // Build and execute query
    let query = postrust_core::query::build_query(&plan, Some(&auth_result.role))?;

    if !query.has_main() {
        return Ok(Response::builder()
            .status(200)
            .body(Body::from("[]"))
            .unwrap());
    }

    let (sql, _params) = query.build_main();
    debug!("Executing SQL: {}", sql);

    // Execute query
    let rows = sqlx::query(&sql)
        .fetch_all(pool)
        .await
        .map_err(|e| postrust_core::Error::Internal(e.to_string()))?;

    // Convert to JSON
    let json_rows: Vec<serde_json::Value> = rows
        .iter()
        .map(|row| {
            use sqlx::{Column, Row};
            let mut map = serde_json::Map::new();
            for column in row.columns() {
                let value: Option<serde_json::Value> = row.try_get(column.name()).ok();
                map.insert(
                    column.name().to_string(),
                    value.unwrap_or(serde_json::Value::Null),
                );
            }
            serde_json::Value::Object(map)
        })
        .collect();

    let body = serde_json::to_string(&json_rows).unwrap_or_else(|_| "[]".to_string());

    Ok(Response::builder()
        .status(200)
        .header("content-type", "application/json")
        .body(Body::from(body))
        .unwrap())
}

fn error_response(error: postrust_core::Error) -> Response<Body> {
    let status = error.status_code().as_u16();
    let body = serde_json::to_string(&error.to_json()).unwrap_or_else(|_| "{}".to_string());

    Response::builder()
        .status(status)
        .header("content-type", "application/json")
        .body(Body::from(body))
        .unwrap()
}