Fedora 26 not connecting to wireless

This is a quick hint in case you suffer from the same issue I had while installing Fedora 26 (alpha).

The installer didn’t manage to connect to my wireless router, a D-Link one. More specifically, it was not getting an IP address from the router. Some problem with DHCP it seems.

If that’s the case, open a terminal (press the Windows key, then type “Terminal” and hit Enter), and type the following command:

sudo sh -c 'echo "send dhcp-client-identifier = hardware;" > /etc/dhcp/dhclient.conf'

Then reconnect to your wireless network. After the first boot – when the system is installed – repeat the command above, just once.

By the way, this is not a new issue. I experienced this on Fedora 25, but curiously at the time the installer (the live system actually) worked fine. Just the installed system suffered from it. Now, with F26, it happened since the beginning. Here’s the bugzilla entry: https://bugzilla.redhat.com/show_bug.cgi?id=1154200.

Hope that helps, happy Fedora!

GNOME Release Party – Success! Hands on soon?

Hey guys, last Saturday we had our [first?] GNOME Release Party here in São Paulo, Brazil. It was very, very productive and most importantly, fun!

Georges already blogged about it, check it out!

Also, we had a feeling that another event, with a more hacking focus would be interesting. So, I setup a meetup in order to see if there are enough people interested in such a hands-on event 🙂

Updates on Timezone extension

Hey, this is a quick post to show the improvements the Timezone extension for GNOME Shell has received since it was born a couple of weeks ago.

  • Support avatars from Gravatar.com and Libravatar.
  • Support GitHub profile. We fetch people’s name, city and avatar from there.
  • Ability to specify a location for people.json file. We support even remote files (e.g.: http://example.com/people.json). This way a whole team can share this file and use a single copy of it!

Here’s a simple people.json file showing the new features:

[
  {
    "github": "jwendell",
    "tz": "America/Sao_Paulo"
  },
  {
    "name": "Niel",
    "gravatar": "niel@example.com",
    "city": "Cape Town",
    "tz": "Africa/Johannesburg"
  }
]

Screenshots:

Summary at the bottom. Clicking will open the preferences dialog
Preferences dialog

Timezone extension for GNOME Shell

I’d like to share with you my first GNOME Shell extension, Timezone: It helps people like me, who work in a distributed (global) team and need to know where and when their coworkers are.

screenshot

It reads a JSON file containing all people data and renders them into a nice overview organized by timezone. See all relevant information on its page: https://github.com/jwendell/gnome-shell-extension-timezone.

Please, install, test it and report any issue you find. Hope it’s useful to anyone as it is for me 🙂

New job: Red Hat

Hello!

It’s with great pleasure that I announce that since last December I am working at Red Hat! I’ve already updated my Linkedin profile but forgot to blog about it 🙂 .

It’s not a secret to anyone that I always admired Red Hat and that I think it is one of the best places to work for people like me, who loves Open Source. So, I consider this a big step in my life and career!

First day
First day in São Paulo office

I’m working in the Cloud Enablement team, which is responsible to bring Middleware products (JBoss, etc) to Red Hat’s PaaS, Openshift. That’s called xPaaS. It’s a entire new world to me: Docker, Kubernetes, Openshift, JBoss, etc… and at the same time it’s a very exciting moment.

I’m still living in São Paulo, but working from home now, which gives me some opportunities 🙂 .

Raleigh
Last week in Red Hat Headquarters

In other news, I’m now an Emeritus Member of the GNOME Foundation. This means that I’m quite a few time without substantial contributions to the project. Sad 🙁 . The good news is that working at Red Hat I’m closer than ever to contribute to Open Source projects! I hope to be back to the game soon 🙂

Hey, talking about cloud… Old but gold:

Systemd journal: What does “systemd-journal: Suppressed N messages from /system.slice/…” mean?

Under pressure, my system was generating lots of messages like this:

# systemctl -l status systemd-journald.service
Jun 24 13:47:23 localhost systemd-journal[155]: Suppressed 15460 messages from /system.slice/...

This means the system is generating lots of messages and journal is configured to drop some of them. This is called rate limit, and is useful to not overload the logging system.

Sometimes, however, you just want to get all messages, or perhaps increase these limits. This can be achieved by setting the variables RateLimitInterval and RateLimitBurst inside the config file /etc/systemd/journald.conf.

Quoting the man page for journal: To turn off any kind of rate limiting, set either value to 0.

Linux: Getting rid of “net_ratelimit: N callbacks suppressed” messages

Linux has a mechanism to avoid a DoS attack – with regard to logging – called rate limit. Every message logged by the kernel (including its modules), with printk(), is checked if it’s allowed to be actually printed through this mechanism.

The limits can be configured by tuning the files /proc/sys/kernel/printk_ratelimit and /proc/sys/kernel/printk_ratelimit_burst. In my machine, the values for these files are 5 and 10, respectively, meaning: It’s allowed 10 messages every 5 seconds. Exceeding this will make the kernel discard the message and print something like “ratelimit N: callbacks suppressed”.

However, the networking code in the kernel has its own limit configuration. They obey the same logic above, they use a different path just to allow independence from the generic logging functions. The files are: /proc/sys/net/core/message_cost and /proc/sys/net/core/message_burst. They are similar to their generic “parents” mentioned above.

The message_cost file contains the interval and message_burst contains the maximum number of messages allowed in that interval.

To disable this mechanism and allow every message to be logged, simply set the interval to 0:

# sysctl -w net.core.message_cost=0

Write “net.core.message_cost=0” to /etc/sysctl.d/some-file to make this change persistent to reboots.

This will make the message “net_ratelimit: N callbacks suppressed” go away. It’s up to you do disable this mechanism. Sometimes it’s just necessary, right?

Recovering lost files after a git reset –hard

This morning I’ve messed things up in my env…

I did a commit yesterday and thought I had pushed it, but not.
Today I did a git pull and was asked to do a merge, because there were changes in the remote.

I totally ignored this (don’t ask me why, perhaps absence of coffee…) and did a git reset –hard HEAD^^

So, yep, I lost my commit that existed only in my machine (this commit in particular was a file addition).

After blaming myself a lot, and a bit of google search, I’ve found this amazing blog post: http://zsoltfabok.com/blog/2012/06/recover-deleted-files-with-git/

I’m summarizing here the steps to have your commit (in my case, the file) back:

git fsck --no-reflog

This command will return a hash for the lost commit, something like

dangling commit fafeade9f348b18f37835ab49dab40172efde693

You can use this hash to do a checkout, for instance, and recover your file. \o/

So, let’s have a bit of coffee now 🙂