[stable/prometheus] Use yaml not literal for alertmanagerFiles (#3777)

- Use yaml not literal for alertmanagerFiles (closes #3576).
- Raise minor release number to mark the updated values structure.
- Fix typo in README associated with yaml not literal for
  serverFiles.

stable/prometheus/Chart.yaml

@@ -1,5 +1,5 @@
 name: prometheus
-version: 5.3.3
+version: 5.4.0
 description: Prometheus is a monitoring system and time series database.
 home: https://prometheus.io/
 icon: https://raw.githubusercontent.com/prometheus/prometheus.github.io/master/assets/prometheus_logo-cb55bb5c346.png

stable/prometheus/README.md

@@ -77,7 +77,7 @@ Assuming you have an existing release of the prometheus chart, named `prometheus
 1. Deploy a new release of the chart with version 5.0+ using prometheus 2.x. In the values.yaml set the scrape config as usual, and also add the `prometheus-old` instance as a remote-read target.
 
    ```
-	  prometheus.yml: |
+	  prometheus.yml:
 	    ...
 	    remote_read:
 	    - url: http://prometheus-old/api/v1/read
@@ -126,7 +126,7 @@ Parameter | Description | Default
 `alertmanager.service.loadBalancerSourceRanges` | list of IP CIDRs allowed access to load balancer (if supported) | `[]`
 `alertmanager.service.servicePort` | alertmanager service port | `80`
 `alertmanager.service.type` | type of alertmanager service to create | `ClusterIP`
-`alertmanagerFiles` | alertmanager ConfigMap entries | `alertmanager.yml`
+`alertmanagerFiles.alertmanager.yml` | Prometheus alertmanager configuration | example configuration
 `configmapReload.name` | configmap-reload container name | `configmap-reload`
 `configmapReload.image.repository` | configmap-reload container image repository | `jimmidyson/configmap-reload`
 `configmapReload.image.tag` | configmap-reload container image tag | `v0.1`

stable/prometheus/templates/alertmanager-configmap.yaml

@@ -10,5 +10,9 @@ metadata:
     release: {{ .Release.Name }}
   name: {{ template "prometheus.alertmanager.fullname" . }}
 data:
-{{ toYaml .Values.alertmanagerFiles | indent 2 }}
-{{- end }}
+{{- $root := . -}}
+{{- range $key, $value := .Values.alertmanagerFiles }}
+  {{ $key }}: |
+{{ toYaml $value | default "{}" | indent 4 }}
+{{- end -}}
+{{- end -}}

stable/prometheus/values.yaml

@@ -644,7 +644,7 @@ pushgateway:
 ## alertmanager ConfigMap entries
 ##
 alertmanagerFiles:
-  alertmanager.yml: |-
+  alertmanager.yml:
     global:
       # slack_api_url: ''