refactor: make env var assertion more intuitive

The problem right now is that the constants that are loaded from the
environment have an additional name if specified. This additional name
is very confusing if you're presented with the error message

Environment variable Alchemy API key is not set.

This makes you wonder if perhaps you have mistyped the variable name.
It's almost always better to just print the variable name as it is
expected in your .env file. One notable exception is perhaps our Web3Up
proof and secret.

That's why this patch changes the approach of assertExists() to only
deal with environment variables (it's not used in any other way
currently) and have the caller specify the variable name and an optional
hint to help the person stumbling over a missing env var error with
additional context.

The name of assertExists() was renamed to getRequiredEnvVar() to better
reflect what the function is doing. The filename was also renamed to
further support this.

Author: pheuberger

src/index.ts

@@ -2,7 +2,7 @@ import "./instrument.js";
 import express, { type Express } from "express";
 import "reflect-metadata";
 import cors from "cors";
-import { assertExists } from "./utils/assertExists.js";
+import { getRequiredEnvVar } from "./utils/envVars.js";
 import { yoga } from "./client/graphql.js";
 import swaggerUi from "swagger-ui-express";
 import swaggerJson from "./__generated__/swagger.json" assert { type: "json" };
@@ -21,7 +21,7 @@ BigInt.prototype.fromJSON = function () {
   return BigInt(this.toString());
 };
 
-const PORT = assertExists(process.env.PORT, "PORT");
+const PORT = getRequiredEnvVar("PORT");
 
 const app: Express = express();
 

src/utils/assertExists.ts

@@ -1,54 +1,18 @@
-import { assertExists } from "./assertExists.js";
+import { getRequiredEnvVar } from "./envVars.js";
 
-export const supabaseCachingUrl = assertExists(
-  process.env.SUPABASE_CACHING_DB_URL,
-  "SUPABASE_CACHING_DB_URL",
-);
-
-export const supabaseCachingApiKey = assertExists(
-  process.env.SUPABASE_CACHING_ANON_API_KEY,
+export const supabaseCachingUrl = getRequiredEnvVar("SUPABASE_CACHING_DB_URL");
+export const supabaseCachingApiKey = getRequiredEnvVar(
   "SUPABASE_CACHING_ANON_API_KEY",
 );
-
-export const supabaseDataUrl = assertExists(
-  process.env.SUPABASE_DATA_DB_URL,
-  "SUPABASE_DATA_DB_URL",
-);
-
-export const supabaseDataServiceApiKey = assertExists(
-  process.env.SUPABASE_DATA_SERVICE_API_KEY,
+export const supabaseDataUrl = getRequiredEnvVar("SUPABASE_DATA_DB_URL");
+export const supabaseDataServiceApiKey = getRequiredEnvVar(
   "SUPABASE_DATA_SERVICE_API_KEY",
 );
-
-export const web3upKey = assertExists(process.env.KEY, "WEB3UP_KEY");
-export const web3upProof = assertExists(process.env.PROOF, "WEB3UP_PROOF");
-
-export const indexerEnvironment = assertExists(
-  process.env.INDEXER_ENVIRONMENT,
-  "INDEXER_ENVIRONMENT",
-);
-
-export const alchemyApiKey = assertExists(
-  process.env.ALCHEMY_API_KEY,
-  "Alchemy API key",
-);
-
-export const infuraApiKey = assertExists(
-  process.env.INFURA_API_KEY,
-  "Infura API key",
-);
-
-export const drpcApiPkey = assertExists(
-  process.env.DRPC_API_KEY,
-  "dRPC API KEY",
-);
-
-export const cachingDatabaseUrl = assertExists(
-  process.env.CACHING_DATABASE_URL,
-  "CACHING_DATABASE_URL",
-);
-
-export const dataDatabaseUrl = assertExists(
-  process.env.DATA_DATABASE_URL,
-  "DATA_DATABASE_URL",
-);
+export const web3upKey = getRequiredEnvVar("KEY", "WEB3UP Key");
+export const web3upProof = getRequiredEnvVar("PROOF", "WEB3UP Proof");
+export const indexerEnvironment = getRequiredEnvVar("INDEXER_ENVIRONMENT");
+export const alchemyApiKey = getRequiredEnvVar("ALCHEMY_API_KEY");
+export const infuraApiKey = getRequiredEnvVar("INFURA_API_KEY");
+export const drpcApiPkey = getRequiredEnvVar("DRPC_API_KEY");
+export const cachingDatabaseUrl = getRequiredEnvVar("CACHING_DATABASE_URL");
+export const dataDatabaseUrl = getRequiredEnvVar("DATA_DATABASE_URL");

src/utils/constants.ts

@@ -0,0 +1,10 @@
+export const getRequiredEnvVar = (variableName: string, hint?: string) => {
+  const variable = process.env[variableName];
+  if (!variable) {
+    throw new Error(
+      `Environment variable ${variableName}${hint ? ` (${hint})` : ""} is not set.`,
+    );
+  }
+
+  return variable;
+};