Helm: Can Helm support to ignore {{expr}} which is just for configuration but not render?

I have a similar use case to have a go style template in a config map. Right now helm is trying to evaluate the template and causing errors in the config map.

I ran into this same/similar problem awhile ago and solved it by embedding including the alerting rules as separate files, as

apiVersion: v1
kind: ConfigMap
metadata:
  name: {{ template "fullname" . }}-rules
  labels:
    chart: "{{ .Chart.Name }}-{{ .Chart.Version | replace "+" "_" }}"
    role: {{ template "fullname" . }}-rulefiles
    prometheus: {{ template "fullname" . }}
data:
  {{ (.Files.Glob "files/kubernetes.rules").AsConfig }}
  {{ (.Files.Glob "files/etcd2.rules").AsConfig }}
  {{ (.Files.Glob "files/custom_alert.rules").AsConfig }}

AFAIK it is extremely difficult to escape {{ }} in a go template, and slurping the files in from elsewhere is much simpler.

The way to escape double curly brackets in Go templates is to use {{ "{{" }}. It's not extremely difficult, just ugly.

I'm going to close this issue as we have two separate solutions to the problem, but please re-open if this hasn't been resolved.

@bacongobbler Hello Matthew, I've been fighting with how to escape curly braces in a Helm template in markdown. Maybe I'm not understanding your solution. How would I render this correctly?
(just a snippet). I've tried raw/endraw, pre, single backslash, double backslash - No success!
thanks for any suggestion...I'm trying to put this in code block with either indents or backticks.

  apiVersion: apps/v1beta1
  kind: Deployment
  metadata:
    name: {{ template "fullname" . }}

@bacongobbler I found the solution. I need to use both pre and &123; &125;

@bacongobbler I found the solution. I need to use both pre and &123; &125;

Could you please show an example?
Is there a way to exclude one yaml from the template engine?

A viable hack is to let Helm render the template as a raw string. Note the opening and closing curly bracket with a backtick:

# Excerpt from a Prometheus Alertmanager yaml
receivers:
- name: slack-receiver
  slack_configs:
  - text: |-
      {{`{{ range .Alerts }}
        *Alert:* {{ .Annotations.summary }}
      {{ end }}`}}

A viable hack is to let Helm render the template as a raw string. Note the opening and closing curly bracket with a backtick:

# Excerpt from a Prometheus Alertmanager yaml
receivers:
- name: slack-receiver
  slack_configs:
  - text: |-
      {{`{{ range .Alerts }}
        *Alert:* {{ .Annotations.summary }}
      {{ end }}`}}

Thank you very much. That solved the big problem

you can also use printf for that:

{{ printf "{{ some value }}" }}

A viable hack is to let Helm render the template as a raw string. Note the opening and closing curly bracket with a backtick:

# Excerpt from a Prometheus Alertmanager yaml
receivers:
- name: slack-receiver
  slack_configs:
  - text: |-
      {{`{{ range .Alerts }}
        *Alert:* {{ .Annotations.summary }}
      {{ end }}`}}

it works, thx

apiVersion: v1
kind: ConfigMap
metadata:
name: {{ template "fullname" . }}-rules
labels:
chart: "{{ .Chart.Name }}-{{ .Chart.Version | replace "+" "_" }}"
role: {{ template "fullname" . }}-rulefiles
prometheus: {{ template "fullname" . }}
data:
{{ (.Files.Glob "files/kubernetes.rules").AsConfig }}
{{ (.Files.Glob "files/etcd2.rules").AsConfig }}
{{ (.Files.Glob "files/custom_alert.rules").AsConfig }}

This didn't work for me.
After banging my head for 2 days was able to make following work!

apiVersion: v1
kind: ConfigMap
metadata:
  name: {{ template "fullname" . }}-rules
  labels:
    chart: "{{ .Chart.Name }}-{{ .Chart.Version | replace "+" "_" }}"
    role: {{ template "fullname" . }}-rulefiles
    prometheus: {{ template "fullname" . }}
data:
  {{- (.Files.Glob "files/kubernetes.rules").AsConfig | nindent 2}}

A viable hack is to let Helm render the template as a raw string. Note the opening and closing curly bracket with a backtick:

# Excerpt from a Prometheus Alertmanager yaml
receivers:
- name: slack-receiver
  slack_configs:
  - text: |-
      {{`{{ range .Alerts }}
        *Alert:* {{ .Annotations.summary }}
      {{ end }}`}}

I can add to the chorus of confirmations that this still works.

And you may need it to get this to work:

https://www.vaultproject.io/docs/platform/k8s/injector/examples/

cat <<EOF >> ./patch.yaml
spec:
  template:
    metadata:
      annotations:
        vault.hashicorp.com/agent-inject: "true"
        vault.hashicorp.com/agent-inject-status: "update"
        vault.hashicorp.com/agent-inject-secret-db-creds: "database/creds/db-app"
        vault.hashicorp.com/agent-inject-template-db-creds: |
          {{- with secret "database/creds/db-app" -}}
          postgres://{{ .Data.username }}:{{ .Data.password }}@postgres:5432/appdb?sslmode=disable
          {{- end }}
        vault.hashicorp.com/role: "db-app"
        vault.hashicorp.com/ca-cert: "/vault/tls/ca.crt"
        vault.hashicorp.com/client-cert: "/vault/tls/client.crt"
        vault.hashicorp.com/client-key: "/vault/tls/client.key"
        vault.hashicorp.com/tls-secret: "vault-tls-client"
EOF

spec:
  groups:
  - name: alertrules.kafkalag
    rules:
    - alert: AssessmentAggregator lag
      expr: sum(samza_pipeline_metrics_consumer_lag{job_name= "AssessmentAggregator"}) > {{ .Values.assessment_aggregator_threshold }}
      for: 5m
      labels:
        severity: critical
      annotations:
        message: {{`"AssessmentAggregator lag is {{$value}}"`}}
        summary: AssessmentAggregator lag is Critical
````
You can add 

{{.......}}
```
and will template properly

A viable hack is to let Helm render the template as a raw string. Note the opening and closing curly bracket with a backtick:

# Excerpt from a Prometheus Alertmanager yaml
receivers:
- name: slack-receiver
  slack_configs:
  - text: |-
      {{`{{ range .Alerts }}
        *Alert:* {{ .Annotations.summary }}
      {{ end }}`}}

Unfortunately this does not work using promtool. https://prometheus.io/docs/prometheus/latest/configuration/unit_testing_rules/

spec:
  groups:
  - name: alertrules.kafkalag
    rules:
    - alert: AssessmentAggregator lag
      expr: sum(samza_pipeline_metrics_consumer_lag{job_name= "AssessmentAggregator"}) > {{ .Values.assessment_aggregator_threshold }}
      for: 5m
      labels:
        severity: critical
      annotations:
        message: {{`"AssessmentAggregator lag is {{$value}}"`}}
        summary: AssessmentAggregator lag is Critical

You can add

{{` ....... `}}

and will template properly

Awesome!!!. It worked. Thanks.