Setting up a GitHub webhook in Jenkins

March 27, 2014August 31, 2015 Josh Reichardt 9 Comments

This post will detail the steps to have Jenkins automatically create a build if it detects changes to a GitHub repository. This can be a very useful improvement to your continuous integration setup with Jenkins because this method is only telling Jenkins to attempt a new build when a change is detected rather than polling on an interval, which can be a little bit inefficient.

There are a few steps necessary to get this process working correctly that I would like to highlight in case I have to do this again or if anybody else would like to set this up. Most of the guides that I found were very out of date so their instructions were a little bit unclear and misleading.

The first step is to configure Jenkins to talk to GitHub. You will need to download and install the GitHub plugin (I am using version 1.8 as of this writing). Manage Jenkins -> Manage Plugins -> Available -> GitHub plugin

After this is installed you can either create a new build or configure an existing build job. Since I already have one set up I will just modify it to use the GitHub hook. There are a few things that need to be changed.

First, you will need to add your github repo:

Then you will then have to tick the box indicated below – “Build when a change is pushed to GitHub”

Also note that Jenkins should have an SSH key already associated with the desired GitHub project.

You’re pretty close to being done. The final step is to head over to GitHub and adjust the settings for the project by creating a webhook for your Jenkins server. Select the repo you’re interested in and click Settings. If you aren’t an admin of the repo you will not be able to modify the settings, so talk to an owner to either finish this step for you or have them grant you admin to make the change yourself.

The GitHub steps are pretty straight forward. Open the “Webhooks & Services” tab -> choose “Configure Services” -> find the Jenkins (GitHub plugin option) and fill it in with a similar URL to the following:

http://<Name of Jenkins server>:8080/github-webhook/

Make sure to tick the active box and ensure it works by running the “Test Hook”. If it comes back with a payload deployed message you should be good to go.

UPDATE

I found an issue that was causing us issues. There is a check box near the bottom of the authentication section labeled “Prevent Cross Site Request Forgery exploits” that needs to be unchecked in order for this particular method to work.

Let me know if you have any issues, I haven’t found a good way to debug or test outside of the message returned from the GitHub configuration page. I did find another alternative method that may work but didn’t need to use it so I can update this if necessary.

If you want more details about web hooks you can check out these resources:

developer documentation.
You can also check out the GitHub Jenkins plugin here.
And another nice guide.

What is DevOps?

March 17, 2014August 31, 2015 Josh Reichardt 14 Comments

Since landing myself in a new and unexplored terrain as a freshly minted DevOps admin, I have been thinking a lot about what exactly DevOps is and how I will translate my skills moving into the position. I am very excited to have the opportunity to work in such a new and powerful area of IT (and at such a sweet company!) but really think I need to lay out some of the groundwork behind what DevOps is, to help strengthen my own understanding and hopefully to help others grasp some of the concepts and ideas behind it.

I have been hearing more and more about DevOps philosophy and its growing influence and adoption in the world of IT, especially in fast paced, cloud and start up companies. From what I have seen so far, I think I people really need to start looking at the impact that DevOps is making in the realm of system administration and how to set themselves up to succeed in this profession moving forward.

Here is the official DevOps description on Wikipedia:

DevOps is a software development method that stresses communication, collaboration and integration between software developers and information technology (IT) professionals. DevOps is a response to the interdependence of software development and IT operations. It aims to help an organization rapidly produce software products and services.

While this is a solid description, there still seems to be a large amount of confusion about what exactly DevOps is so I’d like to address some of the key ideas and views that go along with its mentality and application to system administration. To me, DevOps can be thought of as a combination of the best practices that a career in operations has to offer with many of the concepts and ideas that are used in the world of development. Especially those derived from Agile and Scrum.

The great thing about DevOps is that since it is so new, there is really no universally accepted definition of what it is limited to. This means that those who are currently involved in the DevOps development and adoption are essentially creating a new discipline, adding to it as they go. A current DevOps admin can be described in simple terms as a systems admin that works closely with developers to decrease the gap between operations and development. But that is not the main strength that DevOps offers and really just hits the tip of the ice burg for what DevOps actually is and means.

For one, DevOps offers a sort of cultural shift in the IT environment. Traditionally in IT landscapes, there has been somewhat of a divide between operations and development. You can think of this divide as a wall built between the dev and the ops teams either due to siloing of job skills and responsibilities or how the organization at broader perspective operates. Because of this dissection of duties, there is typically little to no overlap between the tool sets or thought process between the dev or ops teams, which can cause serious headaches trying to get products out the door.

So how do you fix this?

In practical application, the principals of DevOps can put into practice using things like Continuous Integration tools , configuration management, logging and monitoring, creating a standardized test, dev and QA environments, etc. The DevOps mindset and culture has many of its roots in environments of rapid growth and change. An example of this philosophy put in to practice is at start up companies that rely on getting their product to market as quickly as smoothly as possible. The good news is that larger enterprise IT environments are beginning to look at some of the benefits of this approach and starting to tear down the walls of the silos.

Some of the benefits of DevOps include:

Increased stability in your environment (embracing config management and version control)
Faster resolution of problems (decrease MTT)
Continuous software delivery (increasing release frequency brings ideas to market faster)
Much faster software development life cycles
Quicker interaction and feedback loops for key business stakeholders
Automate otherwise cumbersome and tedious tasks to free up time for devs and ops teams

These are some powerful concepts. And the benefits here cannot be underestimated because at the end of the day the company you work for is in the business of making money. And the faster they can make changes to become more marketable and competitive in the market the better.

One final topic I’d like to cover is programming. If you are even remotely interested in DevOps you should learn to program, if you don’t know already. This is the general direction of the discipline and if you don’t have a solid foundation to work from you will not be putting yourself into the best position to progress your career. This doesn’t mean you have to be a developer, but IMO you have have to at least know and understand what the developers are talking about. It is also very useful to know programming for all of the various scripting and automation tasks that are involved in DevOps. Not only will you be able to debug issues with other software, scripts and programs but you will be a much more valuable asset to your team if you can be trusted to get things done and help get product shipped out the door.

Exchange Transport Service won’t start

February 17, 2014August 31, 2015 Josh Reichardt 13 Comments

Due to an outage this weekend, I’d like to take a minute to briefly describe the scenario that occurred and how it was resolved. If you are having trouble starting your Exchange Transport Service then you may potentially be running into the same issue I was having during the outage. Luckily there is an easy remedy for the service failing to start. Basically what was happening was the Exchange message queue database was beginning to fail due to some sort of corruption, causing the Transport service to fail. Because the Transport service wasn’t running, the Edge Sync process was failing, causing external mail delivery to fail. Obviously a big issue, since you cannot receive any email from external domains if this is not working correctly.

To troubleshoot this, there are a few obvious signs that you should look at first. The main thing you should check first is your disk sizes, I wrote about it in my previous post. If your disks are full or are filling up then you are pretty much dead in the water and will need to fix your disk issue. In my scenario the disk sizes were not an issue so the next tool I turned to were the logs. I found a number of interesting entries in the Windows Application Event logs that gave me some clues. I want to detail as many of these messages as I can so that people who are having similar issues know what to look for.

There are a few possible resolutions to this problem. Through some Google searches one solution I found is that you can attempt to repair the corruption in the queue databases by running the database through ESE util. There is no guarantee this will work and it can potentially take a lot of time, depending on the size of your queue database. There is some good information here about the mail queue and how it works.

If you decide to repair the database, the mail queue file is located in the following location:

C:\Program Files\Microsoft\Exchange Server\V14\TransportRoles\data\Queue

Inside this directory is a file called tmp.edb. This is the file that you will need to repair.

The other method is much simpler and was the solution I went with. Instead of attempting to repair the database corruption, simply copy and rename the queue folder and restart the Transport service. Doing this will force the Transport service to create a new, fresh copy of the database queue along with all of the accompanying config files and associated items that are required to get things up and running. It is faster and simpler, IMO. The only problem with this approach is that items that were stuck in the queue when the database corruption occurred will be lost. For me, this was an acceptable loss. If not, you will probably have to use the first method and attempt to repair the database or try to somehow work with a shadow copy or backup somehow to get unstuck.

Monitor your Exchange disk sizes

February 11, 2014August 31, 2015 Josh Reichardt 11 Comments

A word to the wise. If you all of a sudden are unable to send and receive email messages in your Exchange environment, take a look and make sure the Exchange server disks aren’t being filled up. Today I ran across an interesting (and by interesting I mean that this could have caused a serious outage) issue where Windows updates were very routinely being downloaded for our next patch management installation cycle but unknowingly were also causing our email services to stop functioning correctly. I am thankful the scenario didn’t get ugly and luckily this event gives me the opportunity to talk about a few of things that I think might be useful for readers and other admins.

It turns out that this month’s wave of Windows updates caused the disks on our Hub Transport servers to quietly fill up during the day, unbeknownst to any of the admins. In normal circumstances this process is by design and almost never becomes an issue, however in this case there was not enough disk available for Exchange to work correctly. This could have been disastrous had we not known that the disk was starting to fill up. We could have been chasing our tails for a much longer period of time and the situation could have escalated to a more stressful situation. For some reason, the company likes to be able to send and receive emails. Thank god for monitoring that works.

There are a couple things that need to be investigated at this point. First, had we not known that the Windows updates were what were causing the disk to fill up, a logical place to start looking for clues would be to examine the log files on the suspect servers. I would like to take a little bit of time and quickly go over some steps for looking at logs in an Exchange environment, when thinking about potential disk space issues a few things come to mind. Are log files growing rapidly? Did somebody turn on verbose logging and accidentally forget to turn it off? To verify the logs aren’t the issue there are a few places that are good to look. If you are familiar with or have ever used message tracking in Exchange you know how powerful it can be. Sometimes that can also potentially be an issue with your disk filling up. Here is the location that these message tracking logs are stored:

C:\Program Files\Microsoft\Exchange Server\V14\TransportRoles\Logs\MessageTracking

Another location that gets used when you turn on verbose logging for troubleshooting send or receive connectors are the smtpsend and smtpreceive directories. These can fill up quite quickly if you forget to turn off verbose logging on a send or receive connector when are you done troubleshooting. This location is here:

C:\Program Files\Microsoft\Exchange Server\V14\TransportRoles\Logs\ProtocolLog

Finally, there is a location for logging protocol settings on the hub transport. These logs can be found here:

C:\Program Files\Microsoft\Exchange Server\V14\TransportRoles\Logs\ProtocolLog

I would like to point out quickly that any and all of the behaviors of these logging methods can be modified using the Exchange Management Shell, and sometimes for more detailed settings can only be modified by the EMS.

If these quick spot checks don’t uncover any immediate problems another good technique to help gain some insight into where your disk space issues are is to use a tool that enumerates file locations and file sizes. There are a few tools available, one of them I like to use is Space Sniffer. It is fast, easy to use and gives a good visual representation of directory sizes and file sizes. The tool can do much more but in this case we are just interested in finding the disk issue quickly. We were able to quickly find that the size and contents of the %windir%\softwaredistribution\download folder were growing rather quickly. I just happen to know that this is the temporary location that Windows uses to store Windows update files before they are installed.

There are a few things that can be done here. You can either clear the temporary Windows updates files, delete other unnecessary files or you can grow your disks. We were lucky because our Hub Transport servers are VM’s and increasing the disk size of these servers is simple. That seems like the best option if it is a possibility, just in case something like this happens again we will have the additional space so the Exchange servers won’t bog down.

Ultimately we prevented the disaster from occurring but the incident is a great illustration of the lesson I’d like to share. Make sure you have a good monitoring and alerting solution in place. Otherwise you may not have any clue where to start looking. If we did not have a reliable monitoring tool in place it would have been much more difficult to track this problem down in the first place because our Exchange environment is large and complex. Because we have good monitoring tools we were able to quickly identify the problem and resolve it before anything bad happened. On a side note, I am still thinking about how we can take this monitoring and alerting one step further in the future to become proactive instead of reactive but for now the monitoring tools are doing their job and because of this we avoided a potential disaster. If you have any thoughts on proactive monitoring and alerting relating to these types of disk issues let me know, I’d love to hear how you handle it.

Why Computer Science degrees translate to System Administration

January 23, 2014August 31, 2015 Josh Reichardt 8 Comments

I run across a lot of articles and posts that talk about how a degree in Computer Science is usually irrelevant to system administration and that you are just as well off with another degree or no degree at all. I think that line of logic is very short sighted and today I am going (or at least attempt) to explain why. By no means am I criticizing these approaches, in fact I believe in the logic that there is more than one way to skin a cat, and I have found many other highly successful admins that have reached their positions by these alternate means. I just want to quickly clarify that I am not advising readers that taking the CS route to becoming a system admin is the only, right way to go, I am simply relating my own experiences in system administration to my background in CS and making a case of why pursuing a degree in Computer Science, or any other degree in engineering for that matter isn’t going to hurt your chances of becoming a sysadmin.

When you think of Computer Science you think of programming or maybe math, at least I do. Most CS programs these days have a heavy orientation towards programming and the scientific and mathematic applications of programming as it applies to the world around us. As an aside, I am beginning to see many more programs that are tailored to specific disciplines inside the realm of IT which looks promising. This is a great hybrid approach in my opinion because it gives students a chance to look at a few alternate options. Coding isn’t my passion so having an option to become a system administrator without the amount of intense coding from a CS program looks like an attractive approach.

It is true that many of the mundane daily tasks related to system administration don’t involve 8 hours a day of reading and writing code. Because of this I think it is important to characterize and distinguish a sysadmin as somebody who relies on software tools and programming to solve problems and technical challenges but doesn’t necessarily devote all of their time and energy to living in and interacting with code. The relationship of the sysadmin to programming is more of an indirect one, though still very important.

The farther along I wander on in my journey as a sysadmin the more I realize how the CS background is helping me. I have a solid foundation in many of the core concepts that were taught through the CS program, which in turn have indirectly influenced my abilities as a system administrator for the better. The first and most valuable asset my CS background has given me is the ability to write and understand code. This is extremely useful in my daily slew of activities. It allows me to approach problems with a programmatic methodology, it allows me to automate redundant and repeatable tasks with scripts, it gives me intuition into why databases or programs are slow, it allows me to debug issues systematically, and on and on. Obviously these skills can be learned elsewhere but having them rolled up into your education when you learn about Computer Science as part of the package deal is very convenient. I would much rather have this set of skills and have the ability to look at things from a different perspective than have to learn each of these techniques separately. There is no way that somebody coming from a business or other similar background will know about silly things like big O notation or how different algorithms work at a fundamental level, it just isn’t part of their background so they don’t spend time thinking about these things.

This really parlays into other areas well and you are setting yourself up for a diversified and broad horizon for future employment prospects. For example, take a pure sysadmin that knows no programming or CS; at their core they know system administration. But what if they either get burnt out (which is common in this profession) or they don’t keep up the skills to match their position? There is nowhere in the industry for these individuals to turn, unless they want to go into management. That is why I believe individuals that choose not to further their careers are essentially crippling themselves and their future prospects by not knowing how or learning to program, or to at least understand how system administration and programming can relate to each other. With a diverse background the CS sysadmin could potentially move into a Devops role, a pure programming and development role or a management role. With the diverse IT ecosystem, programming and development skills are very much saught after and so the demand is high for these other types of positions and sets of skills.

Another well known fact in the IT industry, which I don’t necessarily agree with but nonetheless exists, is the fact that just having a CS degree will open doors that may not otherwise be open without a degree. I personally believe that a degree shouldn’t dictate your position but by having a degree you set yourself up for some unique opportunities and certainly are not hurting yourself. For example, all other things being equal, somebody scanning through resumes has to select an individual applicant that either has a degree in Computer Science or a degree in Philosophy. Which do you think will be picked? Like I said, I don’t think the hiring process is fair or even has anything to do with skill but can be used as a way to get ahead of the competition in the hiring process and can therefore a degree be valuable by itself as well as viewed as a strategic component in the hiring process if nothing else.

Here’s what I am saying. You don’t have to have a degree in Computer Science to be a great System Administrator. But the CS background definitely equips you with the tools to both understand some of the more abstract technical concepts and ideas and give you a robust framework working through and solving these difficult and complex problems. Ultimately the most important factors in being a good sysadmin (let alone anything else) is a combination of many different things, including a willingness to learn and the amount of experience an individual possesses. There is no cookie cutter way to build the perfect sysadmin and you will invariably find a very diverse group of people in this profession, but a head start with a CS degree is certainly one path that won’t hurt you and is a good attribute of many good sysadmins.