https://github.com/hauleth/plug_telemetry_server_timing

Plug for providing Telemetry metrics within browser DevTools
https://github.com/hauleth/plug_telemetry_server_timing

elixir elixir-plug hacktoberfest metrics plug server-timing telemetry

Last synced: 2 months ago
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Plug for providing Telemetry metrics within browser DevTools

• Host: GitHub
• URL: https://github.com/hauleth/plug_telemetry_server_timing
• Owner: hauleth
• License: mit
• Created: 2019-10-08T10:25:39.000Z (about 5 years ago)
• Default Branch: master
• Last Pushed: 2024-03-19T13:07:41.000Z (10 months ago)
• Last Synced: 2024-10-12T23:20:44.326Z (3 months ago)
• Topics: elixir, elixir-plug, hacktoberfest, metrics, plug, server-timing, telemetry
• Language: Elixir
• Homepage: https://hex.pm/packages/plug_telemetry_server_timing
• Size: 78.1 KB
• Stars: 18
• Watchers: 3
• Forks: 4
• Open Issues: 1
• Metadata Files:
  • Readme: README.md
  • Changelog: CHANGELOG.md
  • Funding: .github/FUNDING.yml
  • License: LICENSE

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README

        
# Plug.Telemetry.ServerTiming

This library provides support for [`Server-Timing`][st] header in Plug

applications by exposing [Telemetry][tm] events as metrics in HTTP headers. This

allows developers to use their's browser DevTools to display server metrics in

readable way.

## Installation

The package can be installed by adding `plug_server_timing` to your list of

dependencies in `mix.exs`:

```elixir

def deps do

  [

    {:plug_telemetry_server_timing, "~> 0.3.0"}

  ]

end

```

Then add `Plug.ServerTiming` to your pipeline **BEFORE** any `Plug.Telemetry`

definitions:

```elixir

plug Plug.Telemetry.ServerTiming

plug Plug.Telemetry, event_prefix: [:my, :plug]

```

And then you need to `install/1` metrics you will want to see in the DevTools:

```elixir

Plug.Telemetry.ServerTiming.install([

  {[:my, :plug, :stop], :duration}

])

```

Now when you will open given page in [browsers with support for

`Server-Timing`][caniuse] you will be able to see the data in DevTools, example

in Google Chrome:

![Google Chrome DevTools image example](assets/example.png)

### Important

You need to place this plug **BEFORE** `Plug.Telemetry` call as otherwise it

will not see it's events (`before_send` callbacks are called in reverse order

of declaration, so this one need to be added before `Plug.Telemetry` one.

## Caveats

This will not respond with events that happened in separate processes, only

events that happened in the Plug process will be recorded.

### WARNING

Current specification of `Server-Timing` do not provide a way to specify event

start time, which mean, that the data displayed in the DevTools isn't trace

report (like the content of the "regular" HTTP timings) but raw dump of the data

displayed as a bars. This can be a little bit confusing, but right now there is

nothing I can do about it.

[caniuse]: https://caniuse.com/#feat=server-timing

[st]: https://w3c.github.io/server-timing/#the-server-timing-header-field

[tm]: https://github.com/beam-telemetry/telemetry

## License

[MIT License](LICENSE)