Say hello to 6.1 and Browsertime 2.1

In this release we have a couple of bug fixes, some new functionality and a super early alpha of something really cool!

Let your plugin add metrics for budget #

One thing that we missed todo in 6.0 was to open up for plugins to add themselves to the budget. With this fix your plugin can add metrics that you then can use in your budget.

In the sitespeedio.config phase (where plugins can talk to each other) make sure to tell the budget plugin that you want it to collect metrics from your plugin. Do that by sending a message of the type budget.addMessageType and add the type of the metrics message you want it to collect.

In this example we tell the budget plugin that it should collect metrics of the type gpsi.pagesummary.

const messageMaker = context.messageMaker;

queue.postMessage(make('budget.addMessageType', {type: 'gpsi.pagesummary'}));

Let your plugin run async JavaScript in BrowserTime #

One of the cool features we released in 6.0 was the ability to let plugins register synchronous JavaScript in Browsertime. In this release you can also run asynchronous JavaScript.

case 'sitespeedio.setup': {
   make('browsertime.asyncscripts', {
     category: 'yourplugin',
     scripts: {
       myValue: 'Promise.resolve(43);'

Configure screenshots #

In this release you can change change the size of the screenshot and choose between png/jpg (to save some extra bytes). We use sharp to manipulate the screenshot. This is what you can do so far:

  --screenshot.type                  Set the file type of the screenshot [choices: "png", "jpg"] [default: "png"]
  --screenshot.png.compressionLevel  zlib compression level. default: 6]
  --screenshot.jpg.quality           Quality of the JPEG screenshot. 1-100 [default: 80]
  --screenshot.maxSize               The max size of the screenshot (width and height). [default: 2000]

Docker with bundled WebPageReplay #

Ohhh we are excited about this: It’s an really early release and you can help us by try it out.

Both and Browsertime have a new Docker container that you should use when you try out WebPageReplay. If you haven’t used WebPageReplay (or other performance tools like mahimahi) the short explanation is that they record your website and replay it locally so when you run your tests, you don’t need to hit the internet. This will give you a chance to have very stable metrics and make it easier to find regressions.

Test it out with #

The Docker container name is sitespeedio/ and you need to pass on the environment variable REPLAY to activate it. Else you just run it as usual. One thing thing though if you want to change the latency (the latency is set on localhost to simulate what it looks like for a real user) you do that with -e LATENCY (default is 100 ms).

Running for Chrome is easy:

docker run --cap-add=NET_ADMIN --shm-size=1g --rm -v "$(pwd):/" -e REPLAY=true sitespeedio/ -n 5 -b chrome

It also works for Firefox (note that we need the skipHar until the next HAR exporter is released):

docker run --cap-add=NET_ADMIN --shm-size=1g --rm -v "$(pwd):/" -e REPLAY=true sitespeedio/ -n 11 --browsertime.skipHar -b firefox

Test it out with Browsertime #

If you are a Browsertime user the correct container is sitespeedio/browsertime:2.1.1-wpr-alpha.

docker run --cap-add=NET_ADMIN --shm-size=1g --rm -v "$(pwd)":/browsertime -e REPLAY=true -e LATENCY=150 sitespeedio/browsertime:2.1.1-wpr-alpha
docker run --cap-add=NET_ADMIN --shm-size=1g --rm -v "$(pwd)":/browsertime -e REPLAY=true -e LATENCY=100 sitespeedio/browsertime:2.1.1-wpr-alpha -b firefox --skipHar -n 11

Feedback #

If you try it out, please get back to us in an issue and tell us how it worked for you!

Fixed #

We also has some fixes in for this release:

Checkout the full Changelog for all changes.