Mail Latency Action

The mail-latency action reads messages from a Maildir, computes the delivery latency of each one from its Received headers, and writes the result as a CSV file.

It is an external action, published in mozership/probe-mail-latency ; it was built into Probe up to v1.21.0. Probe downloads it the first time a workflow uses it, and runs the executable whose SHA-256 the action.yml at the pinned commit names. It needs Probe v1.21.0 or later. The notes of each release  start with the uses line to copy.

The action connects to no host, so its action.yml declares guard: [allow-host], and Probe runs it under --allow-host without --allow-action. It writes its CSV into output_dir, so it declares no read-only: under --read-only, a step that uses it is refused unless --allow-action names it. See Guard.

Basic Syntax

The action reads the messages in a directory and writes the measurements as a CSV file.

- name: Measure delivery latency
  uses: github.com/mozership/probe-mail-latency@2340503ddb7081e1a7e4cc7e4391ac6e5937574d # v0.1.0
  with:
    mail_dir: "/var/mail/probe/new"
    output_dir: "./reports"
  test: res.status == 0

Parameters

Both directories are required: one to read from, one to write to.

mail_dir is read recursively, subdirectories included. A file is measured when it starts with a Return-Path: or Delivered-To: header, which is how a delivered message usually begins. Other files are left alone. Only the headers are read, up to the first empty line, and a header may be folded over several lines or not. The action fails, and writes no CSV, when a measured message has no Date header or no Received header.

Each message becomes one row of the CSV, with these columns:

• Sent Time Offset (sec) and Received Time Offset (sec): when the message was sent and received, counted from the earliest Date in the directory
• Sent Time: the Date header
• Last Received Time and First Received Time: the topmost and the bottom Received header
• End-to-End Latency (sec): from Date to the topmost Received
• Relay Latency (sec): from the bottom Received to the topmost one
• Return Path and File Path: the envelope sender and the file name

Times are written in the local time zone of the machine running probe, as 2006-01-02 15:04:05.

Response Object

The result points at the file that was written.