feat: health check

Author: feloy

src/health.ts

@@ -0,0 +1,57 @@
+import fetch from 'node-fetch';
+import { AbortSignal } from 'node-fetch/externals';
+import { URL } from 'url';
+import { KubeConfig } from './config';
+import { RequestOptions } from 'https';
+
+export class Health {
+    public config: KubeConfig;
+
+    public constructor(config: KubeConfig) {
+        this.config = config;
+    }
+
+    public async readyz(opts: RequestOptions): Promise<boolean> {
+        return this.check('/readyz', opts);
+    }
+
+    public async livez(opts: RequestOptions): Promise<boolean> {
+        return this.check('/livez', opts);
+    }
+
+    private async healthz(opts: RequestOptions): Promise<boolean> {
+        return this.check('/healthz', opts);
+    }
+
+    private async check(path: string, opts: RequestOptions): Promise<boolean> {
+        const cluster = this.config.getCurrentCluster();
+        if (!cluster) {
+            throw new Error('No currently active cluster');
+        }
+
+        const requestURL = new URL(cluster.server + path);
+        const requestInit = await this.config.applyToFetchOptions(opts);
+        const controller = new AbortController();
+        requestInit.signal = controller.signal as AbortSignal;
+        requestInit.method = 'GET';
+
+        return await fetch(requestURL.toString(), requestInit)
+            .then((response) => {
+                const status = response.status;
+                if (status === 200) {
+                    return true;
+                } else if (status === 404) {
+                    if (path === '/healthz') {
+                        // /livez/readyz return 404 and healthz also returns 404, let's consider it is live
+                        return true;
+                    }
+                    return this.healthz(opts);
+                } else {
+                    return false;
+                }
+            })
+            .catch((err) => {
+                return false;
+            });
+    }
+}

src/health_test.ts

@@ -0,0 +1,127 @@
+import { expect } from 'chai';
+import nock from 'nock';
+
+import { KubeConfig } from './config';
+import { Health } from './health';
+import { Cluster, User } from './config_types';
+
+describe('Health', () => {
+    describe('livez', () => {
+        it('should throw an error if no current active cluster', async () => {
+            const kc = new KubeConfig();
+            const health = new Health(kc);
+            await expect(health.livez({})).to.be.rejectedWith('No currently active cluster');
+        });
+
+        it('should return true if /livez returns with status 200', async () => {
+            const kc = new KubeConfig();
+            const cluster = {
+                name: 'foo',
+                server: 'https://server.com',
+            } as Cluster;
+
+            const user = {
+                name: 'my-user',
+                password: 'some-password',
+            } as User;
+            kc.loadFromClusterAndUser(cluster, user);
+
+            const scope = nock('https://server.com').get('/livez').reply(200);
+            const health = new Health(kc);
+
+            const r = await health.livez({});
+            expect(r).to.be.true;
+            scope.done();
+        });
+
+        it('should return false if /livez returns with status 500', async () => {
+            const kc = new KubeConfig();
+            const cluster = {
+                name: 'foo',
+                server: 'https://server.com',
+            } as Cluster;
+
+            const user = {
+                name: 'my-user',
+                password: 'some-password',
+            } as User;
+            kc.loadFromClusterAndUser(cluster, user);
+
+            const scope = nock('https://server.com').get('/livez').reply(500);
+            const health = new Health(kc);
+
+            const r = await health.livez({});
+            expect(r).to.be.false;
+            scope.done();
+        });
+
+        it('should return true if /livez returns status 404 and /healthz returns status 200', async () => {
+            const kc = new KubeConfig();
+            const cluster = {
+                name: 'foo',
+                server: 'https://server.com',
+            } as Cluster;
+
+            const user = {
+                name: 'my-user',
+                password: 'some-password',
+            } as User;
+            kc.loadFromClusterAndUser(cluster, user);
+
+            const scope = nock('https://server.com');
+            scope.get('/livez').reply(404);
+            scope.get('/healthz').reply(200);
+            const health = new Health(kc);
+
+            const r = await health.livez({});
+            expect(r).to.be.true;
+            scope.done();
+        });
+
+        it('should return false if /livez returns status 404 and /healthz returns status 500', async () => {
+            const kc = new KubeConfig();
+            const cluster = {
+                name: 'foo',
+                server: 'https://server.com',
+            } as Cluster;
+
+            const user = {
+                name: 'my-user',
+                password: 'some-password',
+            } as User;
+            kc.loadFromClusterAndUser(cluster, user);
+
+            const scope = nock('https://server.com');
+            scope.get('/livez').reply(404);
+            scope.get('/healthz').reply(500);
+            const health = new Health(kc);
+
+            const r = await health.livez({});
+            expect(r).to.be.false;
+            scope.done();
+        });
+
+        it('should return true if both /livez and /healthz return status 404', async () => {
+            const kc = new KubeConfig();
+            const cluster = {
+                name: 'foo',
+                server: 'https://server.com',
+            } as Cluster;
+
+            const user = {
+                name: 'my-user',
+                password: 'some-password',
+            } as User;
+            kc.loadFromClusterAndUser(cluster, user);
+
+            const scope = nock('https://server.com');
+            scope.get('/livez').reply(404);
+            scope.get('/healthz').reply(200);
+            const health = new Health(kc);
+
+            const r = await health.livez({});
+            expect(r).to.be.true;
+            scope.done();
+        });
+    });
+});