SMTP Email Alerter integration + make generic Alerter steps

docs/book/component-guide/alerters/README.md

@@ -1,72 +1,97 @@
 ---
-description: Sending automated alerts to chat services.
+description: Sending automated alerts to chat services and email.
 icon: message-exclamation
 ---
 
 # Alerters
 
-**Alerters** allow you to send messages to chat services (like Slack, Discord, Mattermost, etc.) from within your
-pipelines. This is useful to immediately get notified when failures happen, for general monitoring/reporting, and also
-for building human-in-the-loop ML.
+**Alerters** allow you to send messages to chat services (like Slack, Discord, etc.) or via email from within your
+pipelines. This is useful to immediately get notified about failures, for general monitoring/reporting, or
+for building human-in-the-loop ML workflows.
 
 ## Alerter Flavors
 
-Currently, the [SlackAlerter](slack.md) and [DiscordAlerter](discord.md) are the available alerter integrations. However, it is straightforward to
-extend ZenML and [build an alerter for other chat services](custom.md).
+Currently, the [SlackAlerter](slack.md), [DiscordAlerter](discord.md), and [SMTP Email Alerter](smtp_email.md) are the available alerter integrations. However, it is straightforward to extend ZenML and [build an alerter for other services](custom.md).
 
-| Alerter                            | Flavor    | Integration | Notes                                                              |
-|------------------------------------|-----------|-------------|--------------------------------------------------------------------|
-| [Slack](slack.md)                  | `slack`   | `slack`     | Interacts with a Slack channel                                     |
-| [Discord](discord.md)              | `discord` | `discord`   | Interacts with a Discord channel                                   |
-| [Custom Implementation](custom.md) | _custom_  |             | Extend the alerter abstraction and provide your own implementation |
+| Alerter                            | Flavor        | Integration   | Notes                                                              |
+|------------------------------------|---------------|---------------|--------------------------------------------------------------------|
+| [Slack](slack.md)                  | `slack`       | `slack`       | Interacts with a Slack channel                                     |
+| [Discord](discord.md)              | `discord`     | `discord`     | Interacts with a Discord channel                                   |
+| [SMTP Email](smtp_email.md)        | `smtp_email`  | `smtp_email`  | Sends email notifications via SMTP                                 |
+| [Custom Implementation](custom.md) | _custom_      |               | Extend the alerter abstraction and provide your own implementation |
 
 {% hint style="info" %}
 If you would like to see the available flavors of alerters in your terminal, you can use the following command:
 
 ```shell
 zenml alerter flavor list
 ```
-
 {% endhint %}
 
-## How to use Alerters with ZenML
+## How to Use Alerters with ZenML
 
-Each alerter integration comes with specific standard steps that you can use out of the box.
+### 1. Register an Alerter
 
-However, you first need to register an alerter component in your terminal:
+First, you register the alerter flavor of your choice. For example, for Slack:
 
 ```shell
-zenml alerter register <ALERTER_NAME> ...
+zenml alerter register my_slack_alerter \
+    --flavor=slack \
+    --slack_token=<YOUR_SLACK_BOT_TOKEN> \
+    --slack_channel_id=<YOUR_SLACK_CHANNEL_ID>
 ```
 
-Then you can add it to your stack using
+Then attach it to your stack:
 
 ```shell
-zenml stack register ... -al <ALERTER_NAME>
+zenml stack register my_stack -al my_slack_alerter ...
 ```
 
-Afterward, you can import the alerter standard steps provided by the respective integration and directly use them in
-your pipelines.
+### 2. Use `alerter_post_step` (Recommended)
+
+ZenML now provides a **unified** step for posting alerts, regardless of which alerter flavor you've chosen. Simply import
+and use `alerter_post_step`, passing an `AlerterMessage` object that you can fill with details:
+
+```python
+from zenml.alerter.steps.alerter_post_step import alerter_post_step
+from zenml.models.v2.misc.alerter_models import AlerterMessage
+from zenml import pipeline
+
+@pipeline
+def my_pipeline():
+    # Construct a message with an optional title, body, and extra metadata
+    msg = AlerterMessage(
+        title="Hello from my pipeline!",
+        body="All checks passed successfully.",
+        metadata={"accuracy": 0.95, "f1_score": 0.92}
+    )
+    result = alerter_post_step(msg)
+    # result is True if successfully posted, else False
+```
 
-## Using the Ask Step for Human-in-the-Loop Workflows
+When you run this pipeline, ZenML will automatically detect which alerter is configured in your active stack, then post
+to Slack, Discord, or send an email, etc. Each flavor interprets the message in its own format (Slack blocks, email HTML, etc.).
+
+### 3. Use `alerter_ask_step` for Human-in-the-Loop Workflows
 
 All alerters provide an `ask()` method and corresponding ask steps that enable human-in-the-loop workflows. These are essential for:
 
 - Getting approval before deploying models to production
 - Confirming critical pipeline decisions  
 - Manual intervention points in automated workflows
 
-### How Ask Steps Work
+#### How Ask Steps Work
 
-Ask steps (like `discord_alerter_ask_step` and `slack_alerter_ask_step`):
+The generic `alerter_ask_step` (and flavor-specific ask steps):
 
 1. **Post a message** to your chat service with your question
 2. **Wait for user response** containing specific approval or disapproval keywords
 3. **Return a boolean** - `True` if approved, `False` if disapproved or timeout
 
 ```python
+from zenml.alerter.steps.alerter_ask_step import alerter_ask_step
+from zenml.models.v2.misc.alerter_models import AlerterMessage
 from zenml import step, pipeline
-from zenml.integrations.slack.steps.slack_alerter_ask_step import slack_alerter_ask_step
 
 @step
 def train_model():
@@ -86,23 +111,31 @@ def deploy_model(model, approved: bool) -> None:
 def deployment_pipeline():
     trained_model = train_model()
     # Ask for human approval before deployment
-    approved = slack_alerter_ask_step("Deploy model to production?")
+    approval_msg = AlerterMessage(
+        title="Deployment Approval",
+        body="Deploy model to production?"
+    )
+    approved = alerter_ask_step(approval_msg)
     deploy_model(trained_model, approved)
 ```
 
-### Default Response Keywords
+If the underlying alerter doesn't support interactive approvals (e.g., SMTP Email), a `NotImplementedError`
+may be raised or it will always return `False`.
+
+#### Default Response Keywords
 
 By default, alerters recognize these response options:
 
 **Approval:** `approve`, `LGTM`, `ok`, `yes`  
 **Disapproval:** `decline`, `disapprove`, `no`, `reject`
 
-### Customizing Response Keywords
+#### Customizing Response Keywords
 
 You can customize the approval and disapproval keywords using alerter parameters:
 
 ```python
-from zenml.integrations.slack.steps.slack_alerter_ask_step import slack_alerter_ask_step
+from zenml.alerter.steps.alerter_ask_step import alerter_ask_step
+from zenml.models.v2.misc.alerter_models import AlerterMessage
 from zenml.integrations.slack.alerters.slack_alerter import SlackAlerterParameters
 
 # Use custom approval/disapproval keywords
@@ -111,18 +144,30 @@ params = SlackAlerterParameters(
     disapprove_msg_options=["stop", "cancel", "❌"]
 )
 
-approved = slack_alerter_ask_step(
-    "Deploy model to production?", 
-    params=params
+approval_msg = AlerterMessage(
+    title="Deployment Approval",
+    body="Deploy model to production?"
 )
+
+approved = alerter_ask_step(approval_msg, params=params)
 ```
 
-### Important Notes
+#### Important Notes
 
 - **Return Type**: Ask steps return a boolean value - ensure your pipeline logic handles this correctly
 - **Keywords**: Response keywords are case-sensitive (except Slack, which converts to lowercase)
 - **Timeout**: If no valid response is received within the timeout period, the step returns `False`
 - **Permissions**: Ensure your bot has permissions to read messages in the target channel
 
+## Specialized Steps: Deprecated
+
+We previously provided specialized steps for Slack, Discord, and Email:
+- `slack_alerter_post_step`, `slack_alerter_ask_step`
+- `discord_alerter_post_step`, `discord_alerter_ask_step`
+- `smtp_email_alerter_post_step`
+
+These steps are **deprecated** and will be removed in a future release. Please migrate to the generic
+`alerter_post_step` and `alerter_ask_step` as shown above.
+
 <!-- For scarf -->
-<figure><img alt="ZenML Scarf" referrerpolicy="no-referrer-when-downgrade" src="https://static.scarf.sh/a.png?x-pxid=f0b4f458-0a54-4fcd-aa95-d5ee424815bc" /></figure>
+<figure><img alt="ZenML Scarf" referrerpolicy="no-referrer-when-downgrade" src="https://static.scarf.sh/a.png?x-pxid=f0b4f458-0a54-4fcd-aa95-d5ee424815bc" /></figure>

docs/book/component-guide/alerters/custom.md

@@ -8,12 +8,16 @@ description: Learning how to develop a custom alerter.
 Before diving into the specifics of this component type, it is beneficial to familiarize yourself with our [general guide to writing custom component flavors in ZenML](https://docs.zenml.io/how-to/infrastructure-deployment/stack-deployment/implement-a-custom-stack-component). This guide provides an essential understanding of ZenML's component flavor concepts.
 {% endhint %}
 
+> **Note**: Once you have implemented your custom alerter, you can post messages via the generic
+[`alerter_post_step`](./README.md#how-to-use-alerters-with-zenml) or [`alerter_ask_step`](./README.md#how-to-use-alerters-with-zenml)
+if your alerter supports interactive approvals.
+
 ### Base Abstraction
 
-The base abstraction for alerters is very basic, as it only defines two abstract methods that subclasses should implement:
+The base abstraction for alerters defines two main methods that subclasses should implement:
 
-* `post()` takes a string, posts it to the desired chat service, and returns `True` if the operation succeeded, else `False`.
-* `ask()` does the same as `post()`, but after sending the message, it waits until someone approves or rejects the operation from within the chat service (e.g., by sending "approve" / "reject" to the bot as a response). `ask()` then only returns `True` if the operation succeeded and was approved, else `False`.
+* `post()` takes either a string or an `AlerterMessage` object, posts it to the desired service, and returns `True` if the operation succeeded, else `False`.
+* `ask()` does the same as `post()`, but after sending the message, it waits until someone approves or rejects the operation from within the service (e.g., by sending "approve" / "reject" as a response). `ask()` then only returns `True` if the operation succeeded and was approved, else `False`.
 
 The `ask()` method is particularly useful for implementing human-in-the-loop workflows. When implementing this method, you should:
 - Wait for user responses containing approval keywords (like `"approve"`, `"yes"`, `"ok"`, `"LGTM"`)
@@ -22,27 +26,43 @@ The `ask()` method is particularly useful for implementing human-in-the-loop wor
 - Return `False` for disapproval, timeout, or any errors
 - Consider implementing configurable approval/disapproval keywords via parameters
 
-Then base abstraction looks something like this:
+The base abstraction looks something like this:
 
 ```python
-from abc import ABC
-from typing import Optional
-from zenml.stack import StackComponent
-from zenml.alerter import BaseAlerterStepParameters
+from typing import Optional, Union
+from zenml.models.v2.misc.alerter_models import AlerterMessage
 
 class BaseAlerter(StackComponent, ABC):
     """Base class for all ZenML alerters."""
 
     def post(
-            self, message: str, params: Optional[BaseAlerterStepParameters]
+            self, message: Union[str, AlerterMessage], 
+            params: Optional[BaseAlerterStepParameters] = None
     ) -> bool:
-        """Post a message to a chat service."""
+        """Post a message to a service.
+
+        Args:
+            message: Either a simple string message or a structured AlerterMessage
+            params: Optional parameters to configure the alert behavior
+
+        Returns:
+            True if the message was successfully delivered, False otherwise
+        """
         return True
 
     def ask(
-            self, question: str, params: Optional[BaseAlerterStepParameters]
+            self, question: Union[str, AlerterMessage],
+            params: Optional[BaseAlerterStepParameters] = None
     ) -> bool:
-        """Post a message to a chat service and wait for approval."""
+        """Post a message to a service and wait for approval.
+
+        Args:
+            question: Either a simple string question or a structured AlerterMessage
+            params: Optional parameters to configure the alert behavior
+
+        Returns:
+            True if the question was approved by a user, False otherwise
+        """
         return True
 ```
 
@@ -58,29 +78,61 @@ Creating your own custom alerter can be done in four steps:
 
     ```python
     import logging
-    from typing import Optional
+    from typing import Optional, Union
 
     from zenml.alerter import BaseAlerter, BaseAlerterStepParameters
+    from zenml.models.v2.misc.alerter_models import AlerterMessage
 
 
     class MyAlerter(BaseAlerter):
         """My alerter class."""
 
         def post(
-            self, message: str, params: Optional[BaseAlerterStepParameters]
+            self, message: Union[str, AlerterMessage], 
+            params: Optional[BaseAlerterStepParameters] = None
         ) -> bool:
-            """Post a message to a chat service."""
+            """Post a message to a service.
+
+            This method handles both string messages and AlerterMessage objects.
+
+            Args:
+                message: Either a string or AlerterMessage object
+                params: Optional parameters for the alert
+
+            Returns:
+                True if successful, False otherwise
+            """
             try:
-                # Implement your chat service posting logic here
-                # e.g., send HTTP request to chat API
-                logging.info(f"Posting message: {message}")
+                # Handle AlerterMessage objects
+                if isinstance(message, AlerterMessage):
+                    # Extract structured data from the AlerterMessage
+                    title = message.title
+                    body = message.body
+                    metadata = message.metadata
+
+                    # Format the message appropriately for your service
+                    formatted_message = f"{title}\n\n{body}"
+
+                    # Use metadata as needed
+                    if metadata:
+                        # Process any custom metadata as needed
+                        pass
+
+                    # Send the formatted message to your service
+                    # ...
+                    print(f"Sending AlerterMessage: {formatted_message}")
+                else:
+                    # Handle simple string messages for backward compatibility
+                    print(f"Sending string message: {message}")
+
                 return True
             except Exception as e:
                 logging.error(f"Failed to post message: {e}")
                 return False
 
         def ask(
-            self, question: str, params: Optional[BaseAlerterStepParameters]
+            self, question: Union[str, AlerterMessage],
+            params: Optional[BaseAlerterStepParameters] = None
         ) -> bool:
             """Post a message to a chat service and wait for approval."""
             try:
@@ -211,4 +263,4 @@ It is important to draw attention to when and how these abstractions are coming
 The design behind this interaction lets us separate the configuration of the flavor from its implementation. This way we can register flavors and components even when the major dependencies behind their implementation are not installed in our local setting (assuming the `MyAlerterFlavor` and the `MyAlerterConfig` are implemented in a different module/path than the actual `MyAlerter`).
 {% endhint %}
 
-<figure><img src="https://static.scarf.sh/a.png?x-pxid=f0b4f458-0a54-4fcd-aa95-d5ee424815bc" alt="ZenML Scarf"><figcaption></figcaption></figure>
+<figure><img src="https://static.scarf.sh/a.png?x-pxid=f0b4f458-0a54-4fcd-aa95-d5ee424815bc" alt="ZenML Scarf"><figcaption></figcaption></figure>