[prometheus-modbus-exporter] fix config-reloader-sidecar deployment

[stefan-kolev]

Summary

The config-reloader-sidecar has never actually deployed for any chart user since it was added, due to two compounding bugs:

1. Typo in template gate. templates/deployment.yaml:57 reads .Values.configReloaderSidecar.enable, but values.yaml provides .enabled (with a 'd'). Helm silently resolves the missing key to nil, so the sidecar block is always skipped — even with the chart's own default value of enabled: true.

2. Missing securityContext override on the sidecar. The openenergyprojects/config-reloader-sidecar image runs as root in order to send signals to the modbus_exporter process via the shared PID namespace. The chart's default podSecurityContext.runAsNonRoot: true then causes kubelet to reject the container with:

   container has runAsNonRoot and image will run as root
   

   The chart provided no per-container securityContext override for the sidecar, so even if the typo were fixed in isolation, the sidecar would CreateContainerConfigError on default chart values.

Changes

• templates/deployment.yaml
  • Rename .Values.configReloaderSidecar.enable → .enabled to match values.yaml.
  • Add imagePullPolicy (was previously omitted).
  • Add a templated container-level securityContext block, sourced from configReloaderSidecar.securityContext.
• values.yaml: provide a default configReloaderSidecar.securityContext with runAsNonRoot: false and runAsUser: 0, with a comment explaining why the override is necessary.
• Chart.yaml: bump chart version 0.1.4 → 0.1.5.

The main modbus_exporter container's container-level securityContext.runAsNonRoot: true is unchanged — only the sidecar gets the explicit root override it needs.

Test plan

Verified live on a Kubernetes cluster running the chart:

• helm lint passes.
• helm template renders both containers, with the sidecar block correctly conditional on .enabled.
• helm upgrade of an existing release: both modbus_exporter and config-reloader-sidecar containers come up Ready (1/1 → 2/2).
• Editing the referenced ConfigMap and waiting now reloads modbus_exporter config without a pod rollout (which is the whole reason the sidecar exists).
• Pre-fix behavior reproduced: with stock 0.1.4, helm template emits no sidecar at all, and explicitly setting configReloaderSidecar.enable: true (workaround) makes the sidecar appear but it then fails with CreateContainerConfigError: container has runAsNonRoot and image will run as root.