T973: add build script for node_exporter package

packages/node_exporter/.gitignore

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+*.tar.gz
+node_exporter-*
+debian

packages/node_exporter/Jenkinsfile

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+// Copyright (C) 2024 VyOS maintainers and contributors
+//
+// This program is free software; you can redistribute it and/or modify
+// in order to easy exprort images built to "external" world
+// it under the terms of the GNU General Public License version 2 or later as
+// published by the Free Software Foundation.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program.  If not, see <http://www.gnu.org/licenses/>.
+@NonCPS
+
+// Using a version specifier library, use 'current' branch. The underscore (_)
+// is not a typo! You need this underscore if the line immediately after the
+// @Library annotation is not an import statement!
+@Library('vyos-build@current')_
+
+def pkgList = [
+    ['name': 'node_exporter',
+     'buildCmd': 'cd ..; ./build.py'],
+]
+// Start package build using library function from https://github.com/vyos/vyos-build
+buildPackage('node_exporter', pkgList, null, true, "**/packages/node_exporter/**")

packages/node_exporter/build.py

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+#!/usr/bin/env python3
+
+from pathlib import Path
+from subprocess import run
+import requests
+import tarfile
+
+VERSION = '1.8.2'
+URL = f'https://github.com/prometheus/node_exporter/releases/download/v{VERSION}/node_exporter-{VERSION}.linux-amd64.tar.gz'
+TARNAME = f'node_exporter-{VERSION}.linux-amd64.tar.gz'
+
+# download the tarball from url
+response = requests.get(URL)
+with open(TARNAME, 'wb') as f:
+    f.write(response.content)
+
+# create the install dir
+path = Path('debian/usr/sbin')
+path.mkdir(parents=True, exist_ok=True)
+
+
+# extract the tarball to current directory
+with tarfile.open(TARNAME, "r:gz") as tar:
+    filenames = tar.getnames()
+    for filename in filenames:
+        if filename.endswith('node_exporter'):
+            tar.extract(filename)
+            break
+
+
+# move the binary to install dir
+Path(filename).rename(f"{path}/{filename.split('/')[1]}")
+
+fpm_cmd = [
+        'fpm', '--input-type', 'dir', '--output-type', 'deb', '--name', 'node-exporter',
+        '--version', VERSION, '--deb-compression', 'gz',
+        '--maintainer', 'VyOS Package Maintainers <[email protected]>',
+        '--description', 'Prometheus exporter for machine metrics',
+        '--license', 'Apache-2.0', '-C', 'debian', '--package', '..'
+
+    ]
+
+run(fpm_cmd)