feat(jenkins): Add Jenkins plugin manager (#6668)

lib/manager/jenkins/__fixtures__/plugins.txt

+email-ext:1.2.3
+
+apache-httpcomponents-client-4-api:4.4.10-2.0 # comment
+authentication-tokens:1.2
+blueocean:1.21.0 # another comment
+#blueocean:1.22.0
+
+# this line is completely ignored

lib/manager/jenkins/__snapshots__/extract.spec.ts.snap

+// Jest Snapshot v1, https://goo.gl/fbAQLP
+
+exports[`manager/jenkins/extract extractPackageFile() extracts multiple image lines 1`] = `
+Array [
+  Object {
+    "currentValue": "1.2.3",
+    "datasource": "jenkins-plugins",
+    "depName": "email-ext",
+    "versioning": "docker",
+  },
+  Object {
+    "currentValue": "4.4.10-2.0",
+    "datasource": "jenkins-plugins",
+    "depName": "apache-httpcomponents-client-4-api",
+    "versioning": "docker",
+  },
+  Object {
+    "currentValue": "1.2",
+    "datasource": "jenkins-plugins",
+    "depName": "authentication-tokens",
+    "versioning": "docker",
+  },
+  Object {
+    "currentValue": "1.21.0",
+    "datasource": "jenkins-plugins",
+    "depName": "blueocean",
+    "versioning": "docker",
+  },
+]
+`;

lib/manager/jenkins/extract.spec.ts

+import { readFileSync } from 'fs';
+import { getName } from '../../../test/util';
+import { extractPackageFile } from './extract';
+
+const pluginsFile = readFileSync(
+  'lib/manager/jenkins/__fixtures__/plugins.txt',
+  'utf8'
+);
+
+const pluginsEmptyFile = readFileSync(
+  'lib/manager/jenkins/__fixtures__/empty.txt',
+  'utf8'
+);
+
+describe(getName(__filename), () => {
+  describe('extractPackageFile()', () => {
+    it('returns empty list for an empty file', () => {
+      const res = extractPackageFile(pluginsEmptyFile);
+      expect(res.deps).toHaveLength(0);
+    });
+
+    it('extracts multiple image lines', () => {
+      const res = extractPackageFile(pluginsFile);
+      expect(res.deps).toMatchSnapshot();
+      expect(res.deps).toHaveLength(4);
+    });
+  });
+});

lib/manager/jenkins/extract.ts

+import * as datasourceJenkins from '../../datasource/jenkins-plugins';
+import { logger } from '../../logger';
+import * as dockerVersioning from '../../versioning/docker';
+import { PackageDependency, PackageFile } from '../common';
+
+export function extractPackageFile(content: string): PackageFile | null {
+  logger.trace('jenkins.extractPackageFile()');
+  const deps: PackageDependency[] = [];
+  const regex = /^\s*(?<depName>[\d\w-]+):(?<currentValue>[^#\s]+).*$/;
+
+  for (const line of content.split('\n')) {
+    const match = regex.exec(line);
+
+    if (match) {
+      const { depName, currentValue } = match.groups;
+      const dep: PackageDependency = {
+        datasource: datasourceJenkins.id,
+        versioning: dockerVersioning.id,
+        depName,
+        currentValue,
+      };
+
+      deps.push(dep);
+    }
+  }
+
+  return { deps };
+}

lib/manager/jenkins/index.ts

+export { extractPackageFile } from './extract';
+
+export const defaultConfig = {
+  fileMatch: ['(^|/)plugins\\.txt'],
+};

lib/manager/jenkins/readme.md

+The Jenkins manager suppports the following format of the plugin list:
+
+```text
+plugin1:1.2.3
+plugin2:4.5 # this is a comment
+
+# this line is ignored
+```
+
+There's no strict specification on the name of the files, but usually it's `plugins.txt`