Add environment variable credential provider

Author: jeskew

packages/credential-provider/__tests__/fromEnv.ts

@@ -0,0 +1,57 @@
+import {
+    ENV_KEY,
+    ENV_SECRET,
+    ENV_SESSION,
+    fromEnv,
+} from "../lib/fromEnv";
+
+const akid = process.env[ENV_KEY];
+const secret = process.env[ENV_SECRET];
+const token = process.env[ENV_SESSION];
+
+beforeEach(() => {
+    delete process.env[ENV_KEY];
+    delete process.env[ENV_SECRET];
+    delete process.env[ENV_SESSION];
+});
+
+afterAll(() => {
+    process.env[ENV_KEY] = akid;
+    process.env[ENV_SECRET] = secret;
+    process.env[ENV_SESSION] = token;
+});
+
+describe('fromEnv', () => {
+    it('should read credentials from known environment variables', async () => {
+        process.env[ENV_KEY] = 'foo';
+        process.env[ENV_SECRET] = 'bar';
+        process.env[ENV_SESSION] = 'baz';
+
+        expect(await fromEnv()()).toEqual({
+            accessKeyId: 'foo',
+            secretKey: 'bar',
+            sessionToken: 'baz',
+        });
+    });
+
+    it('can create credentials without a session token', async () => {
+        process.env[ENV_KEY] = 'foo';
+        process.env[ENV_SECRET] = 'bar';
+
+        expect(await fromEnv()()).toEqual({
+            accessKeyId: 'foo',
+            secretKey: 'bar',
+            sessionToken: void 0,
+        });
+    });
+
+    it(
+        'should reject the promise if no environmental credentials can be found',
+        async () => {
+            try {
+                await fromEnv()();
+                fail('The promise should have been rejected.');
+            } catch (e) {}
+        }
+    );
+});

packages/credential-provider/index.ts

@@ -1,4 +1,5 @@
 export * from './lib/chain';
 export * from './lib/fromCredentials';
+export * from './lib/fromEnv';
 export * from './lib/isCredentials';
 export * from './lib/memoize';

packages/credential-provider/lib/fromEnv.ts

@@ -0,0 +1,22 @@
+import {CredentialProvider} from "./CredentialProvider";
+import {Credentials} from "./Credentials";
+
+export const ENV_KEY = 'AWS_ACCESS_KEY_ID';
+export const ENV_SECRET = 'AWS_SECRET_ACCESS_KEY';
+export const ENV_SESSION = 'AWS_SESSION_TOKEN';
+
+export function fromEnv(): CredentialProvider {
+    return () => {
+        const accessKeyId: string = process.env[ENV_KEY];
+        const secretKey: string = process.env[ENV_SECRET];
+        if (accessKeyId && secretKey) {
+            return Promise.resolve<Credentials>({
+                accessKeyId,
+                secretKey,
+                sessionToken: process.env[ENV_SESSION],
+            });
+        }
+
+        return Promise.reject<Credentials>('Unable to find environment variable credentials.');
+    };
+}