April 1, 2017

An alternate transport for the Matrix Client-Server API

00:00 -0400

Matrix is an open communications protocol that has many great features. However, one flaw that it has is that the baseline specification is based on long-polling HTTP requests, which is not very efficient. In order to address this deficiency, I've created a spec that presents an alternative transport for the Matrix Client-Server API that uses a protocol that was designed for real-time communications instead of using HTTP.

March 13, 2017

The latest additions to my init.el

11:00 -0400

Inspired by xkcd (but using Alt-mousewheel):

(global-set-key (kbd "<M-mouse-5>") 'undo)
(global-set-key (kbd "<M-mouse-4>") 'redo)

And, since I sometimes need to paste from an HTTP request into a buffer:

(defun insert-from-url (url)
  (interactive "MURL: ")
  (let ((url-request-method "GET")
        (dest (current-buffer))
        (src (url-retrieve-synchronously url)))
    (set-buffer src)
    (goto-char (point-min))
    (search-forward "\n\n")
    (set-buffer dest)
    (insert-buffer-substring src (match-end 0))))
March 9, 2017
23:00 -0500
Hubert Chathi: First, @google.com combines Google Talk with Hangouts, and now they are separating the conferencing and chat functionality again
March 3, 2017
15:19 -0500
Hubert Chathi: so true
February 27, 2017
20:11 -0500
Hubert Chathi: Congratulations to all the organizations accepted to GSoC
February 24, 2017
09:56 -0500
Hubert Chathi: Well, thats just embarassing.
February 23, 2017
22:12 -0500
Hubert Chathi: Anyone proxied by @cloudflare.com or using sites proxied by them: your private data may have been leaked #
11:18 -0500
Hubert Chathi: SHA-1 is officially broken #
February 15, 2017
19:02 -0500
Hubert Chathi: RIP Stuart McLean
February 11, 2017
10:00 -0500
Hubert Chathi: Sign the petition to ask the government to honour their promise to fix our electoral system #
January 31, 2017
08:54 -0500
Hubert Chathi: Got our free Parks Canada Discovery Pass yesterday. Get yours at http://www.parksorders.ca/
January 25, 2017

On transparency

21:01 -0500

I've written briefly before about the value of companies being open and transparent. Back then, I wrote that the way that companies react when things go wrong is a good way to differentiate between them. No matter what company you deal with, things will go wrong at one point or another. Some companies try to avoid responsibility, or only tell you that something has happened if you ask them. Others companies are much more open about what happened.

Matrix.org (and the associated Riot.im) is an example of a team that falls into the latter category. And last night's incident is a good example. Their post-mortem blog post is a great example for others to follow. It gives a detailed timeline of what happened and why the outage occurred. And it finishes off with steps that they will take to prevent future incidents.

Kudos to the Matrix.org team for their transparency.

December 25, 2016
09:30 -0500
Hubert Chathi: Merry Christmas
December 1, 2016

Let's Encrypt for Kubernetes

21:08 -0500

A while ago, I blogged about automatic Let's Encrypt certificate renewal with nginx. Since then, I've also set up renewal in our Kubernetes cluster.

Like with nginx, I'm using acme-tiny to do the renewals. For Kubernetes, I created a Docker image. It reads the Let's Encrypt secret key from /etc/acme-tiny/secrets/account.key, and CSR files from /etc/acme-tiny/csrs/{name}.csr. In Kubernetes, these can be set up by mounting a Secrets store and a ConfigMap, respectively. It also reads the current certificates from /etc/acme-tiny/certs/{name}, which should also be set up by mounting a ConfigMap (called certificates), since that is where the container will put the new certificates.

Starting an acme-tiny pod will start an nginx server to store the .well-known directory for the Acme challenge. Running /opt/acme-tiny-utils/renew in the pod will renew the certificate if it will expire within 20 days (running it with the -f option will disable the check). Of course, we want the renewal to be automated, so we want to set up a sort of cron task. Kubernetes has cron jobs since 1.4, but at the time I was setting this up, we were still on 1.3. Kubernetes also does cron jobs by creating a new pod, whereas the way I want this to work is to run a program in an existing pod (though it could be set up to work the other way too). So I have another cron Docker image, which I have set up to run

kubectl exec `kubectl get pods --namespace=lb -l role=acme -o name | cut -d / -f 2` --namespace=lb ./renew sbscalculus.com

every day. That command finds the acme-tiny pod and runs the renew command, telling it to renew the sbscalculus.com certificate.

Now in order for the Acme challenge to work, HTTP requests to /.well-known/acme-challenge/ get redirected to acme-tiny rather than to the regular pods serving those services. Our services are behind our HAProxy image. So I have a 0acmetiny entry (the 0 causes it to be sorted before all other entries) in the services ConfigMap for HAProxy that reads:

      "namespace": "lb",
      "selector": {
        "role": "acme"
      "hostnames": ["^.*"],
      "path": "^/\\.well-known/acme-challenge/.*$",
      "ports": [80]

This causes HAProxy to all the Acme challeges to the acme-tiny pod, while leaving all the other requests alone.

And that's how we have our certificates automatically renewed from Let's Encrypt.

November 21, 2016
21:31 -0500
Hubert Chathi: Congratulations to @riot.im and @matrix.org for the beta release of cross-platform end-to-end encryption
November 8, 2016
08:09 -0500
Hubert Chathi: Americans: hold your nose and vote today. And may the lesser of two evils win.
November 3, 2016
16:34 -0400
Hubert Chathi: My solution to people not changing passwords on their devices: set the default password to "IAmAnIdiotForNotChangingThePassword"
October 25, 2016
09:27 -0400
Hubert Chathi: Amanda's picture was in our local newspaper
September 7, 2016
16:50 -0400
Hubert Chathi: Domain owners, beware of the Chinese Domain Scam. I've gotten some of these emails too.
September 6, 2016

Buildbot latent build slaves

12:28 -0400

I've blogged before about using Buildbot to build our application server. One problem with it is that the build (and testing) process can be memory intensive, which can sometimes exceed the memory that we have available in our Kubernetes cluster. I could add another worker node, but that would be a waste, since we do builds infrequently.

Fortunately, the Buildbot developers have already built a solution to this: latent buildslaves. A latent buildslave is a virtual server that is provisioned on-demand. That means that when a build isn't active, then we don't have to pay for an extra server to be active; we only have to pay for the compute time that we actually need for builds (plus a bit of storage space).

I chose to use AWS EC2 as the basis of our buildslave. Buildbot also supports OpenStack, so I could have just used DreamCompute, which we already use for our Kubernetes cluster, but with AWS EC2, we can take advantage of spot instances and save even more money if we needed to. In any event, the setup would have been pretty much the same.

Setting up a latent buildslave on AWS is pretty straightforward. First, create an EC2 instance in order to build a base image for the buildslave. I started with a Debian image. Then, install any necessary software for the buildslave. For us, that included the buildslave software itself (Debian package buildbot-slave), git, tinc, npm, and Docker. Most of our build process happens inside of Docker containers, so we don't need anything else. We use tinc to build a virtual network with our Kubernetes cluster, so that we can push Docker images to our own private Docker repository.

After installing the necessary software, we need to configure it. It's configured just like a normal buildslave would be configured: I configured tinc, added an ssh key so that it could check out our source code, configured Docker so that it could push to our repository, and of course configured the Buildbot slave itself. Once it's configured, I cleaned up the image a bit (truncated logs, cleared bash history, etc.), and then took a snapshot in the AWS control panel, giving it a name so that it would show up as an AMI.

Finally, I added the latent buildslave in our Buildbot master configuration, giving it the name of the AMI that was created. Once set up, it ran pretty much as expected. I pushed out a change, Buildbot master created a new EC2 instance, built our application server, pushed and deployed it to our Kubernetes cluster, and after a short delay (to make sure there are no other builds), deleted the EC2 instance. In all, the EC2 instance ran for about 20 minutes. Timings will vary, of course, but it will run for less than an hour. If we were paying full price for a t2.micro instance in us-east-1, each build would cost just over 1 cent. We also need to add in the storage cost for the AMI which, given that I started with an 8GB image, will cost us at most 80 cents per month (since EBS snapshots don't store empty blocks, it should be less than that). We probably average about two builds a month, giving us an average monthly cost of at most 83 cents, which is not too bad.