Read db config from environment (#125)

* Read db config from environment

* Updates and tests

* Fix test case

* Simplify further

Author: wiltsecarpenter

src/resolver.ts

@@ -1,27 +1,9 @@
 import {createHmac} from "node:crypto";
-import {readFile} from "node:fs/promises";
-import {homedir} from "node:os";
-import {join} from "node:path";
-import {type CellPiece} from "./markdown.js";
+import type {CellPiece} from "./markdown.js";
 
-export type CellResolver = (cell: CellPiece) => CellPiece;
-
-export interface ResolvedDatabaseReference {
-  name: string;
-  origin: string;
-  token: string;
-  type: string;
-}
+const DEFAULT_DATABASE_TOKEN_DURATION = 60 * 60 * 1000 * 36; // 36 hours in ms
 
-interface DatabaseProxyItem {
-  secret: string;
-}
-
-type DatabaseProxyConfig = Record<string, DatabaseProxyItem>;
-
-interface ObservableConfig {
-  "database-proxy": DatabaseProxyConfig;
-}
+export type CellResolver = (cell: CellPiece) => CellPiece;
 
 interface DatabaseConfig {
   host: string;
@@ -31,59 +13,49 @@ interface DatabaseConfig {
   secret: string;
   ssl: "disabled" | "enabled";
   type: string;
-  url: string;
 }
 
-const configFile = join(homedir(), ".observablehq");
-const key = `database-proxy`;
-
-export async function readDatabaseProxyConfig(): Promise<DatabaseProxyConfig | null> {
-  let observableConfig;
-  try {
-    observableConfig = JSON.parse(await readFile(configFile, "utf-8")) as ObservableConfig | null;
-  } catch {
-    // Ignore missing config file
+function getDatabaseProxyConfig(env: typeof process.env, name: string): DatabaseConfig | null {
+  const property = `OBSERVABLEHQ_DB_SECRET_${name}`;
+  if (env[property]) {
+    const config = JSON.parse(Buffer.from(env[property]!, "base64").toString("utf8")) as DatabaseConfig;
+    if (!config.host || !config.port || !config.secret) {
+      throw new Error(`Invalid database config: ${property}`);
+    }
+    return config;
   }
-  return observableConfig && observableConfig[key];
-}
-
-function readDatabaseConfig(config: DatabaseProxyConfig | null, name): DatabaseConfig {
-  if (!config) throw new Error(`Missing database configuration file "${configFile}"`);
-  if (!name) throw new Error(`No database name specified`);
-  const raw = (config && config[name]) as DatabaseConfig | null;
-  if (!raw) throw new Error(`No configuration found for "${name}"`);
-  return {
-    ...decodeSecret(raw.secret),
-    url: raw.url
-  } as DatabaseConfig;
+  return null;
 }
 
-function decodeSecret(secret: string): Record<string, string> {
-  return JSON.parse(Buffer.from(secret, "base64").toString("utf8"));
-}
-
-function encodeToken(payload: {name: string}, secret): string {
+function encodeToken(payload: {name: string; exp: number}, secret: string): string {
   const data = JSON.stringify(payload);
   const hmac = createHmac("sha256", Buffer.from(secret, "hex")).update(data).digest();
   return `${Buffer.from(data).toString("base64")}.${Buffer.from(hmac).toString("base64")}`;
 }
 
-export async function makeCLIResolver(): Promise<CellResolver> {
-  const config = await readDatabaseProxyConfig();
+interface ResolverOptions {
+  databaseTokenDuration?: number;
+  env?: typeof process.env;
+}
+
+export async function makeCLIResolver({
+  databaseTokenDuration = DEFAULT_DATABASE_TOKEN_DURATION,
+  env = process.env
+}: ResolverOptions = {}): Promise<CellResolver> {
   return (cell: CellPiece): CellPiece => {
     if (cell.databases !== undefined) {
       cell = {
         ...cell,
         databases: cell.databases.map((ref) => {
-          const db = readDatabaseConfig(config, ref.name);
+          const db = getDatabaseProxyConfig(env, ref.name);
           if (db) {
             const url = new URL("http://localhost");
             url.protocol = db.ssl !== "disabled" ? "https:" : "http:";
             url.host = db.host;
             url.port = String(db.port);
             return {
               ...ref,
-              token: encodeToken(ref, db.secret),
+              token: encodeToken({...ref, exp: Date.now() + databaseTokenDuration}, db.secret),
               type: db.type,
               url: url.toString()
             };

test/resolver-test.ts

@@ -0,0 +1,45 @@
+import assert from "node:assert";
+import {makeCLIResolver} from "../src/resolver.js";
+
+describe("resolver", () => {
+  it("resolves a database client", async () => {
+    const resolver = await makeCLIResolver({
+      env: {
+        OBSERVABLEHQ_DB_SECRET_snow2:
+          "eyJuYW1lIjoic25vdzIiLCJ0eXBlIjoic25vd2ZsYWtlIiwiaG9zdCI6ImxvY2FsaG9zdCIsInBvcnQiOiIyODk5Iiwic3NsIjoiZGlzYWJsZWQiLCJvcmlnaW4iOiJodHRwOi8vMTI3LjAuMC4xOjMwMDAiLCJzZWNyZXQiOiJhNzQyOGJjMWY1ZjhhYzlkYTgzZDQ1ZGFlNTMwMDA5NjczY2U5MTRkY2ZmZDM0ZDA5ZTM2ZmUwY2I2M2Y4ZTMxIn0="
+      }
+    });
+    const cell = resolver({
+      type: "cell",
+      id: "",
+      body: "",
+      databases: [{name: "snow2"}]
+    });
+    assert.equal(cell.databases?.length, 1);
+    const database = cell.databases![0];
+    const token = (database as any).token;
+    const tokenDecoded = JSON.parse(Buffer.from(token.split(".")[0], "base64").toString("utf8"));
+    assert.equal(tokenDecoded.name, "snow2");
+    assert.deepStrictEqual(database, {name: "snow2", type: "snowflake", url: "http://localhost:2899/", token});
+  });
+
+  it("throws an error when it can't resolve", async () => {
+    const resolver = await makeCLIResolver({
+      env: {
+        OBSERVABLEHQ_DB_SECRET_snow2:
+          "eyJuYW1lIjoic25vdzIiLCJ0eXBlIjoic25vd2ZsYWtlIiwiaG9zdCI6ImxvY2FsaG9zdCIsInBvcnQiOiIyODk5Iiwic3NsIjoiZGlzYWJsZWQiLCJvcmlnaW4iOiJodHRwOi8vMTI3LjAuMC4xOjMwMDAiLCJzZWNyZXQiOiJhNzQyOGJjMWY1ZjhhYzlkYTgzZDQ1ZGFlNTMwMDA5NjczY2U5MTRkY2ZmZDM0ZDA5ZTM2ZmUwY2I2M2Y4ZTMxIn0="
+      }
+    });
+    try {
+      resolver({
+        type: "cell",
+        id: "",
+        body: "",
+        databases: [{name: "notthere"}]
+      });
+      assert.fail("should have thrown");
+    } catch (error: any) {
+      assert.equal(error.message, 'Unable to resolve database "notthere"');
+    }
+  });
+});