I don't think it is intentional that the default template is valid YAML, it's just meant to be plain text. I'd even argue it's meant to be Markdown. If I understand the use case, you would like to be able to add structured objects (with nesting) to the custom_details field?

I don't think it is intentional that the default template is valid YAML, it's just meant to be plain text. I'd even argue it's meant to be Markdown. If I understand the use case, you would like to be able to add structured objects (with nesting) to the custom_details field?

Correct, our teams prefer that so they can add logic on PagerDuty side depending on the field values.
I tried to keep the logic generic so it would resolve the 2 referenced issues as well.

Have you considered changing Details in the configuration file from map[string]string to map[string]interface{}?

// PagerdutyConfig configures notifications via PagerDuty.
type PagerdutyConfig struct {
...
	Details        map[string]interface{} `yaml:"details,omitempty" json:"details,omitempty"`
}

Would this avoid having to embed YAML inside existing YAML? I haven't checked if this will affect existing configurations, but it would be good to understand if this is a better option.

Have you considered changing Details in the configuration file from map[string]string to map[string]interface{}?

That was the initial approach I though about. It will create a free style format and would require checking the interfaces one by one as they can be either maps or templated strings. I'm open to experiment with it.

Curious to know... Is this going forward ?
Seems a real blessing having PD Custom Details properly rendered from the Alert Payload.

I'll update this PR with the suggested map[string]interface{} to support nested fields.

Thinking about this more, using a template like alerts: {{ .Alerts }} will translate into alert key with value of string as templates are only rendered into strings.

Parsing template results into maps or slices is possible but could be error-prone and we'd need a format for it.
Alternative option could be toggles to include specific details in the payload:

details: ...

details_include:
  alerts: true
  ...