I wanted to read a trace of requests per second I have in a file and use it as the injection pattern in k6. I could do it by reading the values into an array, which is then used as the stages in a ramping arrival rate excutor, like this:

import http from 'k6/http';
import papaparse from 'https://jslib.k6.io/papaparse/5.1.1/index.js';
import { SharedArray } from 'k6/data';

const trace_file = 'PATH_TO_THE_TRACE_FILE';
const trace = new SharedArray('another data name', function () {
  return papaparse.parse(open(trace_file)).data;
});

var stages = []
for (var i of trace) {
  stages.push({ target: trace[i][0], duration: "1s" })
}

export const options = {
  discardResponseBodies: true,
  scenarios: {
    contacts: {
      executor: 'ramping-arrival-rate',
      startRate: 1,
      timeUnit: '1s',
      preAllocatedVUs: 50,
      maxVUs: 1000,
      stages: stages
    },
  },
};

export default function () {
  const url = "http://localhost:8555";
  http.get(url);
}

The current version of Ubuntu Server 20.04 LTS uses netplan in order to configure the network. If it doesn't use cloud-init to provision the network, the network configuration will be in a YAML file in /etc/netplan. There you can change the network parameters, such as the default gateway if you have a fixed connection.

After changing them, run this command to apply them (remember that you may disconnect from the network, so don't run it from a remote connection!):

sudo netplan apply

A more detailed explanation can be found in this very helpful post at linuxize.

I had some dashboards built in Python with Dash. They were using version 1.13.4 and I updated it to version 2.0.0. In addition to converting the imports, as explained in the migration guide, I also had to change state variables because I was getting the error:

ValueError: The state keyword argument may not be provided without the input keyword argument

I didn't understand the explanation in the migration guide. After reading the new documentation about callbacks, I've found that I had to change my app_callbacks. Previously, I had something like this:

@app.callback(
    Output(component_id='wl-plot', component_property='src'),
    [
        Input(component_id='sol-select', component_property='value'),
        Input(component_id='button-apply', component_property='n_clicks'),
    ],
    state=
    [
        State(component_id='base-dir', component_property='value'),
    ]
)

And I had to change it to this:

@app.callback(
    Output(component_id='wl-plot', component_property='src'),
    Input(component_id='sol-select', component_property='value'),
    Input(component_id='button-apply', component_property='n_clicks'),
    State(component_id='base-dir', component_property='value'),
)

So, basically, now you only have a list of Output, Input and State instances and you don need the state=....

I've found this script which is very handy to analyze if you Linux-based system is vulnerable to Spectre and Meltdown. I found this through this talk.

In a previous post I explained how to use Pelican with GitHub pages but didn't explain how to change the theme. I've changed it now to use Flex and it was harder than expected.

Most of the guides I've found talked about cloning pelican-themes in a folder on your system and changing the variable THEME to that folder. However, that doesn't work when you are using GitHub actions to build your site because it won't find that folder.

My solution was cloning the theme I wanted, Flex, to a folder inside the root folder of the blog:

git clone https://github.com/alexandrevicenzi/Flex

Then I set in pelicanconf.py the variable THEME as follows:

THEME = 'Flex'

In order to make it work with GitHub actions, I had to add in the file publi.sh, before calling pelican, this line:

git clone https://github.com/alexandrevicenzi/Flex

After commiting and pushing, it worked.