Add the monitor

1 files changed, 44 insertions, 0 deletions

diff --git a/lib/index.js b/lib/index.js
new file mode 100644
index 0000000..d5d9668
--- /dev/null
+++ b/lib/index.js
@@ -0,0 +1,44 @@
+const { promisify } = require('util');
+const { exec } = require('child_process');
+
+const internals = {
+  kActiveIndicator: 'active',
+  kFieldSeparator: '\n',
+  kKeyValueSeparator: '=',
+  kBlockSeparator: '\n\n',
+  statusCommand: 'systemctl show --no-page -p Id -p ActiveState',
+
+  formatStatusOutput(systemctlText) {
+
+    const blocks = systemctlText.trim().split(internals.kBlockSeparator);
+    return blocks
+      .map((block) => {
+
+        const fields = block.split(internals.kFieldSeparator);
+        return fields.reduce((fieldObject, field) => {
+
+          const [key, value] = field.split(internals.kKeyValueSeparator);
+          return {
+            ...fieldObject,
+            [key]: value
+          }
+        }, {})
+
+      })
+      .reduce((statusObject, service) => {
+
+        return {
+          ...statusObject,
+          [service.Id]: service.ActiveState === internals.kActiveIndicator
+        }
+      }, {});
+  },
+
+  exec: promisify(exec)
+};
+
+module.exports = async (services) => {
+
+  const { stdout } = await internals.exec(`${internals.statusCommand} ${services.join(' ')}`);
+  return internals.formatStatusOutput(stdout);
+};