MS Teams: Auto-detect Power Automate and disable file attachments

[philslab-ninja]

Summary

Auto-detect Power Automate webhook URLs and disable file attachments by default to avoid the 28KB payload limit. Legacy webhook URLs keep files enabled. User configuration always overrides auto-detection.

Background

Microsoft Teams webhooks have a 28KB message size limit:

"The message size limit is 28 KB. When the size exceeds 28 KB, you receive an error."

With the retirement of Office 365 connectors, users are migrating from legacy webhooks (*.webhook.office.com) to Power Automate Workflows (*.api.powerplatform.com). Base64-encoded images in alerts frequently exceed this limit.

Changes

• Add new send_files: Optional[bool] = None parameter to MS Teams sink
• Add _is_power_automate_url() helper to detect Power Automate webhooks
• Auto-disable files for Power Automate URLs (*.api.powerplatform.com)
• Keep files enabled for legacy webhooks (*.webhook.office.com)
• Explicit send_files: true/false always overrides auto-detection
• Update documentation with auto-detection behavior

How it works

URL Pattern	Default send_files
*.api.powerplatform.com	false (auto)
*.webhook.office.com	true (auto)
Any URL with explicit config	Uses configured value

Test plan

• Verify Power Automate webhooks auto-disable file attachments
• Verify legacy webhooks keep file attachments enabled
• Verify explicit send_files: true overrides auto-detection for Power Automate
• Verify explicit send_files: false disables files for legacy webhooks
• Verify text-based content is still sent when files are disabled

References

• Create an Incoming Webhook - Microsoft Learn - Documents 28KB limit
• Retirement of Office 365 connectors - Microsoft 365 Developer Blog - Migration announcement
• Webhooks and connectors overview - Microsoft Learn

Fixes #1994

[CLAassistant]

All committers have signed the CLA.

[coderabbitai]

Walkthrough

Adds an optional send_files sink parameter (with auto-detection for Power Automate URLs), forwards it from MsTeams sink into the sender, and conditionally excludes file attachments when send_files is false; documentation updated with a "File Attachments" subsection and YAML examples.

Changes

Cohort / File(s)	Summary
Documentation docs/configuration/sinks/ms-teams.rst	Adds "File Attachments" subsection describing auto-detection of Power Automate URLs, the send_files override, YAML examples, and notes that text remains sent and prefer_redirect_to_platform unchanged.
Sink params & forwarding src/robusta/core/sinks/msteams/msteams_sink_params.py, src/robusta/core/sinks/msteams/msteams_sink.py	Adds send_files: Optional[bool] = None to MsTeamsSinkParams and forwards sink_config.send_files into MsTeamsSender.send_finding_to_ms_teams.
Sender logic src/robusta/integrations/msteams/sender.py	Adds _is_power_automate_url helper and send_files: Optional[bool]=None parameter to MsTeamsSender.send_finding_to_ms_teams; auto-detects default (disable for Power Automate), and filters out FileBlock attachments when send_files is false before sending.

Sequence Diagram(s)

sequenceDiagram
    participant Config as Sink Config
    participant Sink as MsTeamsSink
    participant Sender as MsTeamsSender
    participant Teams as MS Teams Webhook

    Config->>Sink: sink_config (webhook_url, send_files?)
    Sink->>Sender: send_finding_to_ms_teams(..., send_files=cfg.send_files)
    Sender->>Sender: if send_files is None -> _is_power_automate_url(webhook_url) -> decide send_files
    Sender->>Sender: split blocks into files_blocks and other_blocks
    alt send_files is false
        Sender-->>Sender: drop files_blocks
    else send_files is true
        Sender->>Sender: upload files_blocks as attachments
    end
    Sender->>Teams: send Adaptive Card (with/without attachments)
    Teams-->>Sender: response

Loading

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~20 minutes

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 40.00% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title accurately and concisely summarizes the main change: auto-detecting Power Automate URLs and disabling file attachments by default.
Linked Issues check	✅ Passed	The PR implements all requirements from issue #1994: adds send_files parameter, implements auto-detection for Power Automate URLs, filters FileBlocks when disabled, and updates documentation.
Out of Scope Changes check	✅ Passed	All changes are within scope of issue #1994: parameter addition, auto-detection logic, file filtering, and documentation updates directly address the 28KB payload limit problem.
Description check	✅ Passed	The PR description clearly relates to the changeset, explaining auto-detection of Power Automate URLs to disable file attachments and the new send_files parameter.

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✨ Finishing touches

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[coderabbitai]

Actionable comments posted: 1

🤖 Fix all issues with AI agents

In `@src/robusta/integrations/msteams/sender.py`:
- Around line 22-28: Docstring for _is_power_automate_url is misleading about
legacy domains; update the docstring to remove the incorrect reference to
'*.webhook.office.com' and either omit legacy domain mention or replace it with
the correct retiring domain '*.logic.azure.com' (or state that legacy connectors
are retired) so the description matches the implemented detection (checks for
".api.powerplatform.com" and "/powerautomate/"); keep the function name
_is_power_automate_url and its behavior unchanged.

📜 Review details

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro

📥 Commits

Reviewing files that changed from the base of the PR and between befa7f8 and ed438ac.

📒 Files selected for processing (3)

• docs/configuration/sinks/ms-teams.rst
• src/robusta/core/sinks/msteams/msteams_sink_params.py
• src/robusta/integrations/msteams/sender.py

🚧 Files skipped from review as they are similar to previous changes (1)

• docs/configuration/sinks/ms-teams.rst

🧰 Additional context used

🧬 Code graph analysis (1)

src/robusta/integrations/msteams/sender.py (2)

src/robusta/core/sinks/msteams/msteams_webhook_tranformer.py (2)

• MsTeamsWebhookUrlTransformer (28-69)
• template (53-69)

src/robusta/integrations/msteams/msteams_msg.py (1)

• MsTeamsMsg (28-198)

🔇 Additional comments (4)

src/robusta/integrations/msteams/sender.py (3)

64-89: Excellent documentation for the new parameter.

The docstring clearly explains the tri-state behavior of send_files: auto-detection when None, explicit control when True/False. Adding the parameter at the end with a default value maintains backward compatibility.

---

93-96: Auto-detection correctly uses the transformed webhook URL.

The auto-detection happens after MsTeamsWebhookUrlTransformer.template() is called, ensuring it evaluates the final URL (which may differ from the original due to webhook_override). This is the correct placement.

---

101-112: Clean filtering approach with minimal code change.

The implementation correctly filters FileBlock entries by clearing files_blocks when send_files is False. This preserves the existing code path while preventing file attachments from being included in the Adaptive Card payload.

src/robusta/core/sinks/msteams/msteams_sink_params.py (1)

13-13: Correct the claim about established pattern consistency.

The send_files: Optional[bool] = None implementation does NOT follow the established pattern from other sinks. Telegram, Pushover, and YaMessenger all use send_files: bool = True (simple boolean with default True), while MsTeams introduces a unique tri-state approach with None for auto-detection. This is a departure from the existing pattern, not a consistent implementation.

The tri-state behavior itself is sound—None enables auto-detection, True forces file sending, False disables it—but the justification in the original review is incorrect.

Likely an incorrect or invalid review comment.

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[philslab-ninja]

I created an image with the changes and tested it.

All scenarios work as expected.

1. Autodetection is working correctly ✅

When using power automate no images are sent:

When using legacy Office365 connector images and logs are sent:

2. Override is working correctly ✅

When setting send_files: false for the legacy URL no images or logs are sent:

When setting send_files: true for power automate URL we get an error, as expected:

[arikalon1]

Thanks for the PR @philslab-ninja