refactor: move healthchecker to top level in src

Dockerfile

@@ -14,4 +14,4 @@ EXPOSE 8000
 
 CMD ["node", "dist/server.js"]
 
-HEALTHCHECK --interval=10s --timeout=10s --start-period=5s --retries=3 CMD ["node", "dist/healthcheck/healthcheck.js"]
+HEALTHCHECK --interval=10s --timeout=10s --start-period=5s --retries=3 CMD ["node", "dist/healthcheck.js"]

src/healthcheck/__tests__/healthcheck.spec.ts → src/__tests__/healthcheck.spec.ts

@@ -26,7 +26,7 @@ describe('healthcheck', () => {
   it('should exit with error code 1 if an error occurs', () => {
     const exitSpy = jest.spyOn(process, 'exit').mockImplementation();
 
-    require('../index');
+    require('../healthcheck');
 
     map['error'](new Error());
 
@@ -42,7 +42,7 @@ describe('healthcheck', () => {
   ])('should exit with error code %s if the response has status code %s', (exitCode, statusCode) => {
     const exitSpy = jest.spyOn(process, 'exit').mockImplementation();
 
-    require('../index');
+    require('../healthcheck');
 
     const response = {
       statusCode

src/healthcheck/healthcheck.ts → src/healthcheck.ts

@@ -2,7 +2,7 @@ import http from 'http';
 import path from 'path';
 import fs from 'fs';
 import FormData from 'form-data';
-import { info, trace } from '../logger';
+import { info, trace } from './logger';
 
 const form = new FormData();
 form.append('data', fs.createReadStream(path.resolve('src/healthcheck/rosterFile.rosz')));