mysql exporter: force password env to be defined before `DATA_SOURCE_…

…NAME` (grafana#440)

mysql-exporter/mysql-exporter.libsonnet

@@ -1,12 +1,10 @@
 local k = import 'ksonnet-util/kausal.libsonnet';
 local container = k.core.v1.container;
 local containerPort = k.core.v1.containerPort;
+local envVar = k.core.v1.envVar;
 local deployment = k.apps.v1.deployment;
 
-local secrets = import 'secrets.libsonnet';
-
-
-secrets {
+{
   image:: 'prom/mysqld-exporter:v0.12.1',
   mysql_fqdn:: '%s.%s.svc.cluster.local' % [
     $._config.deployment_name,
@@ -26,22 +24,35 @@ secrets {
     MYSQL_HOST: $.mysql_fqdn,
   },
 
+  // optionally define additional variables before DATA_SOURCE_NAME
+  mysql_additional_env_list:: [],
+
   mysqld_exporter_container::
     container.new('mysqld-exporter', $.image) +
     container.withPorts(k.core.v1.containerPort.new('http-metrics', 9104)) +
     container.withArgsMixin([
       '--collect.info_schema.innodb_metrics',
     ]) +
     container.withEnvMap($.mysqld_exporter_env) +
+    container.withEnvMixin($.mysql_additional_env_list) +
     // Force DATA_SOURCE_NAME to be declared after the variables it references
     container.withEnvMap({
       DATA_SOURCE_NAME: '$(MYSQL_USER):$(MYSQL_PASSWORD)@tcp($(MYSQL_HOST):3306)/',
     }),
 
-
   mysql_exporter_deployment:
     deployment.new('%s-mysql-exporter' % $._config.deployment_name, 1, [$.mysqld_exporter_container]),
 
   mysql_exporter_deployment_service:
     k.util.serviceFor($.mysql_exporter_deployment),
+
+  withSecretPassword(name, key='password'):: {
+    mysqld_exporter_env+:: {
+      MYSQL_PASSWORD:: '',
+    },
+
+    mysql_additional_env_list:: [
+      envVar.fromSecretRef('MYSQL_PASSWORD', name, key),
+    ],
+  },
 }