feat(sensor): email trigger

[gokulav137]

Adding email triggers support using existing email notification service

Resolves #1817

Also added Example and unit tests for email trigger

First time contributor here. Please let me know incase any issues/ changes in design

Email Trigger specification:

EmailTrigger

(Appears on: TriggerTemplate)

EmailTrigger refers to the specification of the email notification trigger.

Field	Description
parameters \[\]TriggerParameter	(Optional) Parameters is the list of key-value extracted from event’s payload that are applied to the trigger resource.
username string	(Optional) Username refers to the username used to connect to the smtp server.
smtpPassword Kubernetes core/v1.SecretKeySelector	(Optional) SMTPPassword refers to the Kubernetes secret that holds the smtp password used to connect to smtp server.
host string	Host refers to the smtp host url to which email is send.
port int32	(Optional) Port refers to the smtp server port to which email is send. Defaults to 0.
to \[\]string	(Optional) To refers to the email addresses to which the emails are send.
from string	(Optional) From refers to the address from which the email is send from.
subject string	(Optional) Subject refers to the subject line for the email send.
body string	(Optional) Body refers to the body/content of the email send.

Example:

apiVersion: argoproj.io/v1alpha1
kind: Sensor
metadata:
  name: webhook
spec:
  dependencies:
    - name: test-dep
      eventSourceName: webhook
      eventName: example
  triggers:
    - parameters:
        - src:
            dependencyName: test-dep
            dataKey: body.to
          dest: email.to.-1
        - src:
            dependencyName: test-dep
            dataTemplate: "Hi {{.Input.body.name}},\n\n\tHello There.\n\nThanks,\nObi"
          dest: email.body
      template:
        name: email-trigger
        email:
          username: username
          smtpPassword:
            key: password
            name: smtp-secret
          # to:
          #   - [email protected]
          #   - [email protected]
          host: smtp.example.net
          port: 587
          from: [email protected]
          subject: Hello There

Checklist:

• My organization is added to USERS.md.

[whynowy]

Thank for submitting the PR!

[whynowy]

Is making it []string better?

[gokulav137]

Making it [] string would better. But argoproj/notifications-engine doesn't support multiple to emails.
This line passes only one to address down.
https://github.com/argoproj/notifications-engine/blob/master/pkg/services/email.go#L84C43-L84C43

[whynowy]

How to send to multiple recipients?

[gokulav137]

I was thinking along the lines that the user can create a mail group at their end and use that.

But if we need to support this out of the box, I think we have to either:

• Modify the notifications-engine to support multiple to emails
  maybe something like

to := String.Split(dest.Recipient, ",")
email := smtp.New(smtp.Options{
........
........
}).WithSubject(subject).WithBody(body).To(to[0], to[1:]...)

in https://github.com/argoproj/notifications-engine/blob/master/pkg/services/email.go#L77-L84
This shouldn't break any existing functionality

OR

• Send multiple email notifications with each of the to addresses. But this isn't ideal.

OR

• we have to implement a different email service

@whynowy , Would be great to get your opinion on this. Thanks

[whynowy]

Can you check how the following is implemented?

https://github.com/argoproj/notifications-engine/blob/master/README.md?plain=1#L73

[gokulav137]

My understanding was that it was sending out multiple emails out with different recipients as mentioned in the second option. As this matches with pattern in other applications like slack where a recipient will be a channel or user.

Hence the suggestion of adding support for comma separated emails for recipients to the email notification service at notification-engine.

But I will take another look at it. Thanks.

[gokulav137]

Cloned the notifications-engine repo and ran it locally.

Its sending the emails separately. So an email will be sent out for each recipient:

apiVersion: cert-manager.io/v1
kind: Certificate
metadata:
  name: another
  annotations:
    notifications.argoproj.io/subscriptions: |
      - trigger: [on-cert-ready]
        destinations:
          - service: email
            recipients: [[email protected], [email protected]]
spec:
  secretName: something
  issuerRef:
    name: letsencrypt-staging
  emailAddresses:
    - [email protected]

I tried adding the comma separated change it worked.

 to := String.Split(dest.Recipient, ",")
 email := smtp.New(smtp.Options{
 ........
 ........
 }).WithSubject(subject).WithBody(body).To(to[0], to[1:]...)

It send an email with multiple to addresses:

apiVersion: cert-manager.io/v1
kind: Certificate
metadata:
  name: another
  annotations:
    notifications.argoproj.io/subscriptions: |
      - trigger: [on-cert-ready]
        destinations:
          - service: email
            recipients: ["[email protected],[email protected]", [email protected]]
spec:
  secretName: something
  issuerRef:
    name: letsencrypt-staging
  emailAddresses:
    - [email protected]

Here one email would be sent with only [email protected] as recipient and another with both.

@whynowy what do you think. Should I go with this approach and raise a pull request there. Looks like it will add to notification-engines functionality too.

[whynowy]

I would suggest:

1. Make the To a []string;
2. Do for loop here to send notifications;
3. If there's a follow up in notification-engine to support multiple recipients, we update it here.

[gokulav137]

Cool, sounds like a good plan. Will do the same. Thanks.

[whynowy]

Please also add a doc in https://github.com/argoproj/argo-events/tree/master/docs/sensors/triggers. Thanks!

[whynowy]

Shall we move it to validate.go?

[gokulav137]

As I understand validate.go does the pre validations when a sensor is created.

To support dynamic recipient address the validation was moved here. So that validation for to addresses will take place during execution.

Please correct me if I am wrong.

[whynowy]

@gokulav137 - you are right, missed that!