feat(helm): support custom TLS config

The following patch adjusts the podMonitor and serviceMonitor resource. The
static configuration `tlsConfig` is replaced so that the TLS configuration can be
configured individually by the user.

The option `insecureSkipVerify: true` has been removed as it is a security risk.
Users also have the option of redefining the `insecureSkipVerify` property
directly via `tlsConfig` if necessary. With regard to the previous rbac auth
option, however, this is superfluous.

Furthermore, the schema, i.e. HTTP or HTTPS, can now be defined to tell
Prometheus which protocol should be used for communication.

The following sample configuration specifies that the x509-certificate-exporter
encrypts requests via HTTPS and the HTTP client must authenticate itself via
HTTPS (client auth).

```yaml
prometheusServiceMonitor:
  tlsConfig:
    caFile: /etc/prometheus/tls/ca/ca.crt
    certFile: /etc/prometheus/tls/app2app/tls.crt
    keyFile: /etc/prometheus/tls/app2app/tls.key
    insecureSkipVerify: false
    serverName: prometheus-x509-certificate-exporter

prometheusPodMonitor:
  tlsConfig:
    caFile: /etc/prometheus/tls/ca/ca.crt
    certFile: /etc/prometheus/tls/app2app/tls.crt
    keyFile: /etc/prometheus/tls/app2app/tls.key
    insecureSkipVerify: false
    serverName: prometheus-x509-certificate-exporter
```

Important Note: The `serverName` attribute must correspond to the CommonName or a
Subject Alternative Name (SAN) of the TLS certificate. If this is not the case,
prometheus will reject the connection trying to match the IP address of the pod
with the CommonName / SAN.

The client certificate and private key as well as the certificate of the
certificate authorithy must be mounted additionally via the `extraVolumes` and
`extraVolumeMounts` option. This configuration is not standard and must also be
implemented by the user if TLS client authentication is required.

Signed-off-by: Markus Pesch <[email protected]>

deploy/charts/x509-certificate-exporter/README.md

@@ -427,14 +427,18 @@ hostPathsExporter:
 | prometheusServiceMonitor.scrapeInterval | string | `"60s"` | Target scrape interval set in the ServiceMonitor |
 | prometheusServiceMonitor.scrapeTimeout | string | `"30s"` | Target scrape timeout set in the ServiceMonitor |
 | prometheusServiceMonitor.extraLabels | object | `{}` | Additional labels to add to ServiceMonitor objects |
-| prometheusServiceMonitor.metricRelabelings | list | `[]` | Metrics relabel config for the ServiceMonitor, see: https://github.com/prometheus-operator/prometheus-operator/blob/main/Documentation/api.md#monitoring.coreos.com/v1.Endpoint |
+| prometheusServiceMonitor.metricRelabelings | list | `[]` | Metric relabel config for the ServiceMonitor, see: https://github.com/prometheus-operator/prometheus-operator/blob/main/Documentation/api.md#monitoring.coreos.com/v1.Endpoint |
 | prometheusServiceMonitor.relabelings | list | `[]` | Relabel config for the ServiceMonitor, see: https://github.com/prometheus-operator/prometheus-operator/blob/main/Documentation/api.md#monitoring.coreos.com/v1.Endpoint |
+| prometheusServiceMonitor.scheme | string | `"http"` | Scheme config for the ServiceMonitor, see: https://github.com/prometheus-operator/prometheus-operator/blob/main/Documentation/api.md#monitoring.coreos.com/v1.Endpoint |
+| prometheusServiceMonitor.tlsConfig | object | `{}` | Custom TLS configuration, see: https://github.com/prometheus-operator/prometheus-operator/blob/main/Documentation/api.md#monitoring.coreos.com/v1.TLSConfig |
 | prometheusPodMonitor.create | bool | `false` | Should a PodMonitor object be installed to scrape this exporter. For prometheus-operator (kube-prometheus) users. |
 | prometheusPodMonitor.scrapeInterval | string | `"60s"` | Target scrape interval set in the PodMonitor |
 | prometheusPodMonitor.scrapeTimeout | string | `"30s"` | Target scrape timeout set in the PodMonitor |
 | prometheusPodMonitor.extraLabels | object | `{}` | Additional labels to add to PodMonitor objects |
 | prometheusPodMonitor.metricRelabelings | list | `[]` | Metric relabel config for the PodMonitor, see: https://github.com/prometheus-operator/prometheus-operator/blob/main/Documentation/api.md#monitoring.coreos.com/v1.Endpoint |
 | prometheusPodMonitor.relabelings | list | `[]` | Relabel config for the PodMonitor, see: https://github.com/prometheus-operator/prometheus-operator/blob/main/Documentation/api.md#monitoring.coreos.com/v1.Endpoint |
+| prometheusPodMonitor.scheme | string | `"http"` | Scheme config for the PodMonitor, see: https://github.com/prometheus-operator/prometheus-operator/blob/main/Documentation/api.md#monitoring.coreos.com/v1.Endpoint |
+| prometheusPodMonitor.tlsConfig | object | `{}` | Custom TLS configuration, see: https://github.com/prometheus-operator/prometheus-operator/blob/main/Documentation/api.md#monitoring.coreos.com/v1.TLSConfig |
 | prometheusRules.create | bool | `true` | Should a PrometheusRule object be installed to alert on certificate expiration. For prometheus-operator (kube-prometheus) users. |
 | prometheusRules.alertOnReadErrors | bool | `true` | Should the X509ExporterReadErrors alerting rule be created to notify when the exporter can't read files or authenticate with the Kubernetes API. It aims at preventing undetected misconfigurations and monitoring regressions. |
 | prometheusRules.readErrorsSeverity | string | `"warning"` | Severity for the X509ExporterReadErrors alerting rule |

deploy/charts/x509-certificate-exporter/templates/podmonitor.yaml

@@ -19,9 +19,11 @@ spec:
     scrapeTimeout: {{ .Values.prometheusPodMonitor.scrapeTimeout }}
     {{- if .Values.rbacProxy.enable }}
     bearerTokenFile: /var/run/secrets/kubernetes.io/serviceaccount/token
-    scheme: https
+    {{- end }}
+    scheme: {{ .Values.prometheusPodMonitor.scheme }}
+    {{- with .Values.prometheusPodMonitor.tlsConfig }}
     tlsConfig:
-      insecureSkipVerify: true
+    {{- . | toYaml | nindent 6 }}
     {{- end }}
     {{- with .Values.prometheusPodMonitor.metricRelabelings }}
     metricRelabelings:

deploy/charts/x509-certificate-exporter/templates/servicemonitor.yaml

@@ -19,9 +19,11 @@ spec:
     scrapeTimeout: {{ .Values.prometheusServiceMonitor.scrapeTimeout }}
     {{- if .Values.rbacProxy.enable }}
     bearerTokenFile: /var/run/secrets/kubernetes.io/serviceaccount/token
-    scheme: https
+    {{- end }}
+    scheme: {{ .Values.prometheusServiceMonitor.scheme }}
+    {{- with .Values.prometheusServiceMonitor.tlsConfig }}
     tlsConfig:
-      insecureSkipVerify: true
+    {{- . | toYaml | nindent 6 }}
     {{- end }}
     {{- with .Values.prometheusServiceMonitor.metricRelabelings }}
     metricRelabelings:

deploy/charts/x509-certificate-exporter/values.yaml

@@ -240,6 +240,10 @@ prometheusServiceMonitor:
   metricRelabelings: []
   # -- Relabel config for the ServiceMonitor, see: https://github.com/prometheus-operator/prometheus-operator/blob/main/Documentation/api.md#monitoring.coreos.com/v1.Endpoint
   relabelings: []
+  # -- Scheme config for the ServiceMonitor, see: https://github.com/prometheus-operator/prometheus-operator/blob/main/Documentation/api.md#monitoring.coreos.com/v1.Endpoint
+  scheme: http
+  # -- Custom TLS configuration, see: https://github.com/prometheus-operator/prometheus-operator/blob/main/Documentation/api.md#monitoring.coreos.com/v1.TLSConfig
+  tlsConfig: {}
 
 prometheusPodMonitor:
   # -- Should a PodMonitor object be installed to scrape this exporter. For prometheus-operator (kube-prometheus) users.
@@ -254,6 +258,10 @@ prometheusPodMonitor:
   metricRelabelings: []
   # -- Relabel config for the PodMonitor, see: https://github.com/prometheus-operator/prometheus-operator/blob/main/Documentation/api.md#monitoring.coreos.com/v1.Endpoint
   relabelings: []
+  # -- Scheme config for the PodMonitor, see: https://github.com/prometheus-operator/prometheus-operator/blob/main/Documentation/api.md#monitoring.coreos.com/v1.Endpoint
+  scheme: http
+  # -- Custom TLS configuration, see: https://github.com/prometheus-operator/prometheus-operator/blob/main/Documentation/api.md#monitoring.coreos.com/v1.TLSConfig
+  tlsConfig: {}
 
 prometheusRules:
   # -- Should a PrometheusRule object be installed to alert on certificate expiration. For prometheus-operator (kube-prometheus) users.