Support gzipped pushgateway requests (#508)

Author: vpalmisano

CHANGELOG.md

@@ -36,6 +36,8 @@ project adheres to [Semantic Versioning](http://semver.org/).
     `processRequests` metrics along with information about any other types of
     async resources that these metrics do not keep a track of (like timers).
 
+- Support gzipped pushgateway requests
+
 ## [14.0.1] - 2021-11-02
 
 ### Changed

lib/pushgateway.js

@@ -3,6 +3,7 @@
 const url = require('url');
 const http = require('http');
 const https = require('https');
+const { gzipSync } = require('zlib');
 const { globalRegistry } = require('./registry');
 
 class Pushgateway {
@@ -79,6 +80,12 @@ async function useGateway(method, job, groupings) {
 			this.registry
 				.metrics()
 				.then(metrics => {
+					if (
+						options.headers &&
+						options.headers['Content-Encoding'] === 'gzip'
+					) {
+						metrics = gzipSync(metrics);
+					}
 					req.write(metrics);
 					req.end();
 				})

test/pushgatewayTest.js

@@ -1,6 +1,7 @@
 'use strict';
 
 const nock = require('nock');
+const { gzipSync } = require('zlib');
 
 describe('pushgateway', () => {
 	const Pushgateway = require('../index').Pushgateway;
@@ -177,6 +178,33 @@ describe('pushgateway', () => {
 				expect(mockHttp.isDone());
 			});
 		});
+
+		it('should use gzip request', () => {
+			const mockHttp = nock('http://192.168.99.100:9091', {
+				reqheaders: {
+					'Content-Encoding': 'gzip',
+				},
+			})
+				.post(
+					'/metrics/job/testJob',
+					gzipSync('# HELP test test\n# TYPE test counter\ntest 100\n'),
+				)
+				.reply(200);
+
+			instance = new Pushgateway(
+				'http://192.168.99.100:9091',
+				{
+					headers: {
+						'Content-Encoding': 'gzip',
+					},
+				},
+				registry,
+			);
+
+			return instance.pushAdd({ jobName: 'testJob' }).then(() => {
+				expect(mockHttp.isDone());
+			});
+		});
 	};
 
 	describe('global registry', () => {