Category: Links

Git Tips From the Pros

I just came across some useful Git tips on a net tuts+ article  Git Tips From the Pros which includes:

  • Staging your commits in hunks;
  • Grabbing a file from another branch without changing branches;
  • Ignoring changes in a tracked file;
  • Zero-ing out a branches history; and
  • Some very useful aliases.

MySQL 5.6 – Memcached / NoSQL Support and More

MySQL 5.6 has been released with some interesting new features and performance increases:

  • What’s New in MySQL 5.6
  • DBA and Developer Guide to MySQL 5.6
  • InnoDB Integration with memcached:MySQL 5.6 includes a NoSQL interface, using an integrated memcached daemon that can automatically store data and retrieve it from InnoDB tables, turning the MySQL server into a fast “key-value store” for single-row insert, update, or delete operations. You can still also access the same tables through SQL for convenience, complex queries, bulk operations, application compatibility, and other strengths of traditional database software.

    With this NoSQL interface, you use the familiar memcached API to speed up database operations, letting InnoDB handle memory caching using its buffer pool mechanism. Data modified through memcached operations such as ADD, SET, INCR are stored to disk, using the familiar InnoDB mechanisms such as change buffering, the doublewrite buffer, and crash recovery. The combination of memcached simplicity and InnoDB durability provides users with the best of both worlds.

  • Multi-threaded Slaves
  • Improved IPv6 Support – both in the bind to address option and the INET_ATON() function.
  • Replication improvements.

All in all, some nice new features. Especially the memcached integration.

That said, MariaDB seems to be making inroads on MySQL with some distributions considering a switch. Some interesting reading from that project includes:

Adventures with LDAP (OpenLDAP) – SSL, Multi-Master Replication and Monitoring

In my career to date, I successfully managed to avoid all but the periphery engagement in OpenLDAP. Until recently that is – we had to build a Microsoft Exchange like environment with open source software in a way that was closely integrated and easily managed. But, more on that another time. For anyone else diving into OpenLDAP, here are some articles on my experiences that I have penned:

Securing LDAP with TLS / SSL

This is a continuation of a previous post, Creating an LDAP Addressbook / Directory where we add SSL encryption to the directory.

In our case, we used a signed Unified Communications Certificate (UCC) (also known as a Subject Alternative Names (SAN) Certificate) from GoDaddy. The following will work for those as well as standard signed certificates. I have not tested with wildcard certificates. If you want to use a self-signed certificate, see the TLS and SSL section of Ubuntu’s OpenLDAP documentation as well as notes at the end of this document.

GoDaddy (or any other signing authority) will, when presented with a CSR (Certificate Signing Request), return a signed certificate as well as their own CA cert. You will already have your private key which you used to generate the CSR. With this information, prepare a file called tls.ldif with (for example):

dn: cn=config
add: olcTLSCACertificateFile
olcTLSCACertificateFile: /etc/ssl/gd_bundle.crt
-
add: olcTLSCertificateFile
olcTLSCertificateFile: /etc/ssl/webmail.opensolutions.ie.crt
-
add: olcTLSCertificateKeyFile
olcTLSCertificateKeyFile: /etc/ssl/webmail.opensolutions.ie.key

And apply the change via:

ldapmodify -Y EXTERNAL -H ldapi:/// -f tls.ldif

On Ubuntu (you own distribution may vary here), you need to add the SSL service by editing /etc/default/slapd and updating the SLAPD_SERVICES line to read:

SLAPD_SERVICES="ldap:/// ldapi:/// ldaps:///"

and then restart the server (/etc/init.d/slapd restart). You should now consider firewalling the standard port (389) to force users to use the encrypted SSL port.

Following our example with Thunderbird, you can now update your LDAP directory configuration by setting the hostname to match the subject name in your UCC / certificate (e.g. abook.opensolutions.ie) and the port to 636.

Notes for Self Signed Certificates

If you are using a self-signed certificate, you need to ensure a couple of things. Let’s assume you created a self-signed certificate for abook.opensolutions.ie. Clients need a special configuration parameter for untrusted / self-signed certificates. Copy your self-signed certificate (e.g. /etc/ssl/webmail.opensolutions.ie.crt above) to the client machine(s) – say /etc/ssl/certs/abook.crt.

Now, on the client machine, add the following line to /etc/ldap/ldap.conf:

TLS_CACERT /etc/ssl/certs/abook.crt

Secondly, the hostname you use to access the LDAP server must also match the certificate subject name – i.e. use abook.opensolutions.ie in this example rather than an IP address / alternative hostname.

For OpenVPN Fans – Optimising for GE Networks

I came across this article today which discusses OpenVPN optimisations for Gigebit Ethernet networks.

http://community.openvpn.net/openvpn/wiki/Gigabit_Networks_Linux

It also shows the phenomenal improvement that can be made thanks to the AES-NI instruction set on newer Intel and AMD chips.

Git Web Applications (aka GitHub Alternatives)

I’ve been through the mill with a few of these and it’s a growing list of options. I should start by saying that I love GitHub and use it regularly for a large number of projects (including some of my own, some for my company and some for my customers). The only problem I have with GitHub is that I just haven’t made the jump to trust it with our proprietary code – the primary asset of the company. Particularly after a high profile security breech.

Now, nothing I’ve come across yet comes close to GitHub. But two we use daily have good matching features:

  • Gitorious –  whether they intended it or not, it’s a good clone of GitHub but always a little behind on features. It’s also a Ruby on Rails application and the documentation is getting far better. When we started, it was pretty… shite, to be honest. Installing and upgrading was a pain. They have addressed this with http://getgitorious.com/ which includes a virtual appliance for VirtualBox so you can be up and running in minutes.
  • Atlassian Stash – if you’re a small team (<= 10 users) then this could be for you. Installation is pretty easy, it looks great, is very fast (over HTTP/S, but it’s inbuilt SSH client is extremely slow) and is very easy to use. Pull requests are also done really really well. It’s a full Java webapp so it does require some CPU and memory. For <= 10 users, my definite favorite. Thereafter though it gets expensive – e.g. for up to 25 users you’ll fork out $1,800 / annum. That’s not entirely unaffordable but if you’re using Stash, then you may also be using their other products such as Jira, Confluence, Bamboo, Fisheye and Crucible. Now that adds up to a hefty bill!

One’s I have not tested and so cannot speak authoritively on include:

  • GitLab – Looks like a very interesting alternative.
  • RhodeCode – they say it will “change the way you manage your code”.
  • Gitolite – a quick look at the available information for this definitely puts it in the also ran category. There’s no polish or anything nice to entice one to even try it.
  • Gitosis – in their own words: “Manage git repositories, provide access to them over SSH, with tight access control and not needing shell accounts”. The project appears dead.

 

So it’s finally happened…

RIPE put out a press release today:

RIPE NCC Begins to Allocate IPv4 Address Space From the Last /8

14 Sep 2012

On Friday 14 September, 2012, the RIPE NCC, the Regional Internet Registry (RIR) for Europe, the Middle East and parts of Central Asia, distributed the last blocks of IPv4 address space from the available pool.

This means that we are now distributing IPv4 address space to Local Internet Registries (LIRs) from the last /8 according tosection 5.6 of “IPv4 Address Allocation and Assignment Policies for the RIPE NCC Service Region“.

This section states that an LIR may receive one /22 allocation (1,024 IPv4 addresses), even if they can justify a larger allocation. This /22 allocation will only be made to LIRs if they have already received an IPv6 allocation from an upstream LIR or the RIPE NCC. No new IPv4 Provider Independent (PI) space will be assigned.

It is now imperative that all stakeholders deploy IPv6 on their networks to ensure the continuity of their online operations and the future growth of the Internet.

In other words, for all intents and purposes, Europe (and Central Asia and the Middle East) is out of IPv4 addresses. Funnily enough, I’m actually happy that this long predicted day has arrived and we can start the next phase of IPv6 deployment.

Thunderbird 15 Released with Chat – But Shite Error Handling

I’ve just moved a couple of my chat and IRC accounts over to Thunderbird 15 to see how they look. After all, one communications application is better than three. Mozilla have a good instruction set here and they work well for standard chat accounts.

However, most corporations using in house XMPP servers with self signed certificates and these fail with no error messages whatsoever. It was by fluke I found this post: How to Make Thunderbird Chat Work with Most XMPP/Jabber Accounts. Thanks for doing the legwork Rod, this helped a lot.

 

Try Git In Your Browser

I know, I know. The fourth Git post in a row…

But, in case you missed it or in case you’d like to try Git without installing any software, then checkout http://try.github.com/

Today [GitHub are] launching a unique and easy way, in the format of a Code School interactive course, for new Git and GitHub users to try both the tool and the service without a single bit of software installation.

If you know of a developer, designer, or other knowledge worker that would benefit from using Git but that hasn’t made the leap just yet, send them over to try.github.com when they have a spare 15 minutes.

Centralised Logging

I’m currently looking at some centralised logging tools and the following stand out:

  • Octopussy – one I cam across a long time ago but looking at some of the others below it may be past its sell by date?
  • Graylog2 – GSOH (in dating parlance) – “Manage your logs in the dark and have lasers going and make it look like you’re from space.“
  • logstash – “a tool for managing events and logs. You can use it to collect logs, parse them, and store them for later use (like, for searching). Speaking of searching, logstash comes with a web interface for searching and drilling into all of your logs.“
  • Kibana - You have logs. Billions of lines of data. You shipped, dated it, parsed it and stored it. Now what do you do with it? Now you make sense of it… Kibana is an alternative browser based interface for Logstash… that allows you to efficiently search, graph, analyze and otherwise make sense of a mountain of logs.

Kibana has a Bootstrap UI and is written in PHP which immediately bumps it up my list 😉