monitoring-8.x-1.x-dev/modules/prometheus/monitoring_prometheus.module

<?php

use Drupal\Core\Form\FormStateInterface;

/**
 * Implements hook_form_FORM_ID_alter() for \Drupal\monitoring\Form\MonitoringSettingsForm.
 */
function monitoring_prometheus_form_monitoring_settings_alter(&$form, FormStateInterface $form_state, $form_id) {
  $config = \Drupal::config('monitoring_prometheus.settings');

  $allowed_ips = '';
  if ($allowed_ips_config = $config->get('allowed_ips')) {
    $allowed_ips = implode("\r\n", $allowed_ips_config);
  }

  $form['allowed_ips'] = [
    '#type' => 'textarea',
    '#title' => t('Allowed Prometheus IPs'),
    '#default_value' => $allowed_ips,
    '#description' => t("Specify IPs that are allowed to access the /metrics url that monitoring_prometheus provides. Enter one IP per line. This doesn't bypass the permission based access control."),
  ];

  $custom_labels = '';
  if ($custom_labels_config = $config->get('custom_labels')) {
    foreach ($custom_labels_config as $label_name => $label_value) {
       $custom_labels .= "$label_name=$label_value" . "\r\n";
    }
  }

  $form['custom_labels'] = [
    '#type' => 'textarea',
    '#title' => t('Custom labels'),
    '#default_value' => $custom_labels,
    '#description' => t('Specify custom labels that will be applied to each Gauge. Enter one label per line using this example syntax: environment=production.'),
  ];

  if (\Drupal::moduleHandler()->moduleExists('token')) {
    $form['token_help'] = [
      '#theme' => 'token_tree_link',
      '#token_types' => ['file'],
    ];
    $form['custom_labels']['#description'] .= ' ' . t('Tokens will be replaced.');
  }

  $form['#submit'][] = 'monitoring_prometheus_settings_form_submit';
}

/**
 * Form submission handler for monitoring_prometheus_form_monitoring_settings_alter().
 *
 * @see motinoring_prometheus_form_monitoring_settings_alter()
 */
function monitoring_prometheus_settings_form_submit($form, FormStateInterface $form_state) {
  $config = \Drupal::configFactory()->getEditable('monitoring_prometheus.settings');

  $allowed_ips = explode("\r\n", $form_state->getValue('allowed_ips'));
  $config->set('allowed_ips', array_filter($allowed_ips));

  $labels = [];
  $label_lines = explode("\r\n",  $form_state->getValue('custom_labels'));
  foreach ($label_lines as $line) {
    $parts = explode('=', $line);
    if (count($parts) < 2) {
      continue;
    }
    $labels[trim($parts[0])] = trim($parts[1]);
  }
  $config->set('custom_labels', array_filter($labels));
  $config->save();
}