Snowflake support

lib/commands.js

@@ -55,7 +55,7 @@ export async function add(argv, reset = false) {
   // DB credentials
   if (!reset) {
     url = await question(
-      "PostgreSQL or MySQL Database URL (including username and password): "
+      "PostgreSQL, MySQL, or Snowflake Database URL (including username and password): "
     );
   }
 

lib/server.js

@@ -10,6 +10,7 @@ import serializeErrors from "./serialize-errors";
 import {notFound, unauthorized, exit} from "./errors";
 import mysql from "./mysql";
 import postgres from "./postgres";
+import snowflake from "./snowflake";
 
 export function server(config, argv) {
   const development = process.env.NODE_ENV === "development";
@@ -25,7 +26,13 @@ export function server(config, argv) {
   } = config;
 
   const handler =
-    type === "mysql" ? mysql(url) : type === "postgres" ? postgres(url) : null;
+    type === "mysql"
+      ? mysql(url)
+      : type === "postgres"
+      ? postgres(url)
+      : type === "snowflake"
+      ? snowflake(url)
+      : null;
   if (!handler) {
     return exit(`Unknown database type: ${type}`);
   }

lib/snowflake.js

@@ -0,0 +1,99 @@
+import {json} from "micro";
+import {URL} from "url";
+import JSONStream from "JSONStream";
+import snowflake from "snowflake-sdk";
+
+export default url => {
+  url = new URL(url);
+  const {host: account, username, password, pathname, searchParams} = new URL(
+    url
+  );
+  const connection = snowflake.createConnection({
+    account,
+    username,
+    password,
+    database: pathname.slice(1),
+    schema: searchParams.get("schema"),
+    warehouse: searchParams.get("warehouse"),
+    role: searchParams.get("role")
+  });
+
+  return async function query(req, res) {
+    const body = await json(req);
+    const {sql, params} = body;
+
+    const client = await new Promise((resolve, reject) => {
+      if (connection.isUp()) return resolve(connection);
+      snowflake.configure({ocspFailOpen: false});
+      connection.connect((err, conn) => {
+        if (err) reject(err);
+        else resolve(conn);
+      });
+    });
+
+    const statement = client.execute({sqlText: sql, binds: params});
+    try {
+      const stream = statement.streamRows();
+
+      await new Promise((resolve, reject) => {
+        stream
+          .once("end", resolve)
+          .on("error", reject)
+          .pipe(JSONStream.stringify(`{"data":[`, ",", "]"))
+          .pipe(res, {end: false});
+      });
+    } catch (error) {
+      if (!error.statusCode) error.statusCode = 400;
+      throw error;
+    }
+
+    const schema = {
+      type: "array",
+      items: {
+        type: "object",
+        properties: statement
+          .getColumns()
+          .reduce(
+            (schema, column) => (
+              (schema[column.getName()] = dataTypeSchema(column)), schema
+            ),
+            {}
+          )
+      }
+    };
+    res.end(`,"schema":${JSON.stringify(schema)}}`);
+  };
+};
+
+// https://github.com/snowflakedb/snowflake-connector-nodejs/blob/master/lib/connection/result/data_types.js
+const array = ["null", "array"],
+  boolean = ["null", "boolean"],
+  integer = ["null", "integer"],
+  number = ["null", "number"],
+  object = ["null", "object"],
+  string = ["null", "string"];
+function dataTypeSchema(column) {
+  switch (column.getType()) {
+    case "binary":
+      return {type: object, buffer: true};
+    case "boolean":
+      return {type: boolean};
+    case "fixed":
+    case "real":
+      return {type: column.getScale() ? number : integer};
+    case "date":
+    case "timestamp_ltz":
+    case "timestamp_ntz":
+    case "timestamp_tz":
+      return {type: string, date: true};
+    case "variant":
+    case "object":
+      return {type: object};
+    case "array":
+      return {type: array, items: {type: object}};
+    case "time":
+    case "text":
+    default:
+      return {type: string};
+  }
+}

package.json

@@ -1,4 +1,7 @@
 {
+  "name": "@observablehq/database-proxy",
+  "description": "A local proxy to connect private Observable notebooks to private databases",
+  "version": "1.0.1",
   "bin": {
     "observable-database-proxy": "./bin/observable-database-proxy"
   },
@@ -11,11 +14,9 @@
     "pg": "^7.11.0",
     "pg-query-stream": "^2.0.0",
     "serialize-error": "^4.1.0",
+    "snowflake-sdk": "^1.5.0",
     "yargs": "^13.2.4"
   },
-  "name": "@observablehq/database-proxy",
-  "description": "A local proxy to connect private Observable notebooks to private databases",
-  "version": "1.0.1",
   "devDependencies": {
     "nodemon": "^1.19.1"
   },
@@ -24,5 +25,9 @@
     "test": "echo \"Error: no test specified\" && exit 1"
   },
   "author": "Observable",
-  "license": "ISC"
+  "license": "ISC",
+  "repository": {
+    "type": "git",
+    "url": "https://github.com/observablehq/database-proxy.git"
+  }
 }