Automating the Automation Tool

Automation tools are excellent, no doubt, but as you get acclimatised to how good they are you always thinking of ways of trimming off the fat from the unnecessary time you spend using them. Take your CI (Continuous Integration) tool for example - at my current job we currently make heavy use of Atlassian's Bamboo for the majority of our automation. We have developed a number of scripts to do the actual work but we use Bamboo's interface to pass parameters to the build. 

Personally I'm really poor at doing repeatable, mundane tasks that don't really engage my brain however require a decent level of concentration. One such activity is going to Bamboo's UI, finding the correct plan and entering in a bunch of parameters in order to run our scripts in a particular way. 

This click happy process doesn't do much for my sanity, especially when you are doing this numerous times a day and are prone to mistakes due to complete boredom. 

Enter scriptural, my little repository of scripts that I'm putting together for mundane tasks that I can automate. One such task is running Bamboo builds from a little python script which will then check the progress up to a certain length of time. This allows me to define the parameters in a file for future use and change them as required. I don't have to even go to the Bamboo UI now as my script can wait until the build is complete and report back to me on success or failure.

Now you might say I'm being overly precious of my time here, but the next time you're clicking through a UI to complete a task that you've done twenty times before, copy pasting values, and maybe making a mistake - think to yourself, is there a better way to do this? Sure UI's are fancy and nice to look at, but if I've seen it before am I that interested? I wonder is there an API sitting behind this UI...

With the availability of API's that most tools now have, chances are that you too can be more productive by creating a little script that runs in a fraction of the time that you would have spent with your mouse clicking away. 

Check out my example's in the repository to see how I've done it. Suggestions welcome...
    

Pessimism and Optimism - Finding the balance

Pessimism is often seen as the negative in many situations, however, is too much optimism just as bad?

In a uncharacteristic departure from my usual blogs on technical problems, and possible solutions, I'd like to offer some food for thought on the social factors that effect projects, timelines and expectations. 

As someone who tries wherever possible to be optimistic about whether or not I can deliver outcomes to the customer, I sometimes wonder whether or not being too optimistic is detrimental. 
      For example if I say that I'll get something done for a specific date (the optimist in me) but it turns out that it's a larger body of work than I originally thought, I'd rather go above and beyond in order to meet the date than let people down. Now, I'm not saying that doing extra to meet deadlines is incorrect, far from it, but if it's happening constantly it may mean I am not learning from this experience. Am I masking an underlying problem that I didn't understand the work to be done? Or that I am poor at estimating the time it needs to complete a body of work? Is optimism in these cases taking precedence of realism?

Enter pessimism. Should I be more pessimistic about what can be done in order that peoples expectations are met without me having to constantly do extra to get it done? Or will this lead to bad relations with the people that you are working with?

Like everything it's the balance that counts. Without a healthy dose of pessimism I think that our promises to get work done will end up in letting people down or burn out in trying to make up for poor estimation. In contrast without optimism we would not be able to have drive to reach beyond our current situation and make things better than the status quo. 
      Therefore, I think the balance in the two end up being realism - the ability to deliver the things that you say you'll deliver in a time frame, that's achievable in your working day. I'd be really interested in what others think on this topic, whether this rambling is right or wrong.

Let's cover pragmatism another day...

AWS RDS MySQL SSL

Following my previous post of SSL with ELB's and instances I'd like to write a quick post about SSL and RDS MySQL. This is worth another blog post because it behaves slightly differently than your normal apache http or tomcat servers. 

This is because the SSL is enforced at the user level and not at the server port level. Typically when you disable insecure traffic to a particular server you will disable the port that it is listening on for insecure traffic - such as port 80 for the apache web server. 

MySQL is different, you still connect through the default port (3306), or whatever port you have configured it to run, but the difference is the way you connect. In order to ensure secure communication you must first create a user which requires SSL to connect:

First connect to the RDS instance as the root user:

mysql -h myinstance.123456789012.us-east-1.rds.amazonaws.com -P 3306 -u root -p

You can then create users in the specific way:

GRANT SELECT, INSERT, UPDATE, DELETE on db_name.* to 'encrypted_user'@'%' IDENTIFIED BY 'suprsecret' REQUIRE SSL;FLUSH PRIVILEGES;

You can now test this with the mysql client that you used earlier to connect to the database earlier:

mysql -h myinstance.123456789012.us-east-1.rds.amazonaws.com -u encrypted_user -p --ssl_ca=mysql-ssl-ca-cert.pem --ssl-verify-server-cert

The above should prompt you for the password that you set up above, and allow you to connect to the database securely. 

This is the database server end complete. The next part is to configure your application to use SSL to connect to the database securely. There are a number of ways in which you can complete this, for this example I'm going to configure a java application.

For this example we're going to configure the JDK to allow the secure connection. There are a number of options here, including application container specific configurations but this way has the advantage that all java applications (container or otherwise) will be able to connect.

First get the RDS MySQL server certificate from AWS:

wget https://rds.amazonaws.com/doc/mysql-ssl-ca-cert.pem

Now import this into the java trust store (replace $JAVA_HOME as necessary):

$JAVA_HOME/bin/keytool -importcert -alias rds -keystore $JAVA_HOME/jre/lib/security/cacerts -storepass changeme -file ./auspost-root-ca.cer -noprompt

Connecting to the MySQL database is the same as before however you now specify three new options in your connection string which connect using SSL:

jdbc:mysql://myinstance.123456789012.us-east-1.rds.amazonaws.com:3306?useSSL=true&verifyServerCertificate=true&requireSSL=true

For brevity I will not include the rest of the code that you use in java in order to connect.

AWS and SSL - ELB to instance, Instance to ELB

At a glance

Here's the top tips to remember when attempting to enable SSL from an ELB to an instance and from that instance to another ELB:

• ELB's don't like backend self signed intermediate/root certificates, they need the actual certificate that the instance server is presenting
• Instances are quite happy to use the root certificate when connecting to a server presenting a signed certificate.
• Openssl and curl are your friends for testing (explained in detail below):

openssl s_client -connect <elb_dns>:443 -CAfile server.crt

• You can redirect your ELB listeners to listen on an un-secure port but communicate to the instance securely which is handy for testing
• Use ELB health checks with SSL in order to get continuous verification that SSL is working

In the detail - What we're attempting to achieve

SSL (TLS) is the standard for encrypting traffic between a client and a server. One of the best explanations that I've seen about it is here so I'll leave you to read through (I know I found it useful) and get an overview of SSL. 

In this exercise we'll be attempting to enable encrypted traffic from an ELB to an instance and from that instance to another ELB. For example say if I have a web tier and an application tier, I would typically have an ELB in front of each, therefore I need to configure both front and back end certificates on each ELB and also the instances.

I'll be using a certificate which has been signed by an internal root CA, as it's a little more complicated and more like a scenario that you'll be presented with when trying to complete SSL with your own server. Openssl have docs on creating signing requests and self signed certificates.

ELB configuration

A great guide for creating HTTPS ELB's is already defined by the kind people at AWS so I'll only concentrate on the parts that tripped me up.

Front End

Front end certificates in AWS are stored in IAM, allowing you to choose them when creating new ELB's. This is pretty smart as you'll typically use the same certificates for many ELB's. Here, it's just a matter of selecting an existing certificate or uploading a new one per the guide.

Back End

This was a real pain. I assumed that ELB's would work in the same way that the bundle file would in your OS, that is, that you could upload the root certificate to the backend of the ELB and it would be enough to work with the certificate being presented with by the instance. However this was not the case, so my number one tip, is to forego trying the certificate chain and just upload the certificate that is being presented by the instance, uploading the certificate to the backend is describe in the the AWS guide.

Testing

Finally we get to do some testing. I completed this using openssl to check the front end certificate and then curl to test getting a page from my web server once it was configured (see below).

openssl s_client -connect <elb_dns_name>:443 -CAfile /tmp/root.crt

This will connect to your ELB and verify that the root certificate you have specified locally will work with the certificate being presented by your ELB. You should get an OK if everything is configured correctly.

Instance Configuration

In this case I'm going to go with a simple example and use an apache web server configuration for SSL. There are numerous detailed posts out there about configuring apache for SSL so I'll go over the very minimum that will pertain to the AWS ELB specifics. 

Front End

Your instance (in this case apache) will need to be configured to present a SSL certificate to the client (the ELB). In order to do this edit the httpd.conf or vhost conf (more info here) that you have configured to listen on 443 to have these values:

SSLEngine on
SSLCertificateFile /path/to/www.example.com.crt
SSLCertificateKeyFile /path/to/www.example.com.key

As we learned in the explanation of SSL, the certificate, which is just a fancy public key, only works correctly with a corresponding private key file in order to decrypt the data that the client is sending to the server. After restarting the apache server you should be able to view the certificates that the server is presenting:

openssl s_client -showcerts -connect localhost:443

Back End

This is where the configuration is a bit easier and you can generally use a root certificate as opposed to the certificate that is being presented by the ELB. The advantage of this is that the root certificate will generally be valid for longer meaning you don't have to change them as often. 

For this example I'm importing the root certificate to the operating system bundle file that most tools use by default, including curl. Working with RHEL 6.5 we can complete the following command to import the certificate:

openssl x509 -text -in /tmp/server.crt >> /etc/pki/tls/certs/ca-bundle.crt

This can then be verified by the following command:

openssl verify -CAfile /etc/pki/tls/certs/ca-bundle.crt /tmp/server.crt

Testing

Front end testing of the apache web server can be completed by redirecting your un-secure (port 80) listener on your web ELB to talk to the secure port of your instance, like the following:

You can then connect to you ELB via http and know that it's connecting to your instance securely. This is just an option when you want to test individual configurations.

For backend, not only will you want to verify that the certificate is installed correctly (using openssl verify), but you'll also want to check that using the updated bundle to connect to the ELB will work correctly, this can be done with the following:

openssl s_client -connect <elb_dns_name>:443 

This should return you a bunch of text (including the certificate presented by the ELB) but at the bottom you should get an OK if everything is configured correctly. 

Finally: End to End testing

Considering that you'll have a page on your web server (like an index.html file or something) you can use curl to get the file securely through the ELB. I completed this on a VM that I had already installed the root certificate in the ca-bundle with the following command:

curl -v https://<elb_dns_name>/index.html

If everything is configured correctly then you should not notice anything different that using simple http, and you should get your page displayed on the command line.

Added Extras

Constant SSL certificate Health Check

One tip that I got from a colleague of mine is to configure your health check on the AWS ELB to use SSL in the health check, meaning that you'll get continuous verification that the SSL certificate is valid between your ELB and instance. This is particularly useful when considering that certificates expire:

Verify ssl key matches certificate

Another handy thing to verify, if you're not generating the public/private key yourself, is to make sure that the certificate matches the key. This is explained very well in another article. 

Redirecting everything past root in apache

Ever needed to do some maintenance on an Apache web server? Well I do, and I had been wanting to redirect everyone to a maintenance webpage so that they would see that the temporary link instead of any of the actual website. 

I used to do this by putting in place a different configuration file for the Apache web server and allowing it to redirect to the maintenance page, with the following being the main line in the configuration file:

DocumentRoot /var/www/html/maintenance

This was a pain for two reasons:

1. It meant that I had to go in and save the actual config file off to another temp file, then rename the maintenance config file to be the actual config file
2. When anyone requested a webpage that wasn't the DocumentRoot of the website it would not get redirected to the maintenance page

So after some ooogooglygoogling I was able to find the following nugget:

RewriteEngine Off
RewriteCond   %{REQUESR_URI} !=/index.html
RewriteRule   ^ /var/www/html/maintenance/index.html

in the configuration file of the actual website Apache config. This means that I can keep the same configuration file for my maintenance and my actual site, doing away with any pesky moving and renaming etc. and switch between the maintenance and production with just putting the rewrite engine off or on.

It also means that anyone requesting a webpage that is not at the route of the website will be directed back up to the maintenance page. It does this by matching anything from the start of the line - denoted by the '^' i.e. the start of the line, and redirecting to the html file denoted in the second part of the RewriteRule directive.

This is much easier for me maintaining less files, and a more natural feel when people have to be redirected going to the site.

First attempt at some sort of continuous deployment

So I've heard of this continuous deployment concept and it all sounds great. I am keen to give it a go myself but am unsure where to start. So rather than attempt this with a production application in work I pick a nice small app that I've written to manage some of our application config.

This is a small web application hosted on one of our servers which has a database for persistence. Not much you might say but still has got the ingredients to try some sort of automatic deployment. To give you an idea of what I was trying to get away from I need to describe the evolution of the deployment.

What I started with

When writing the application I was not at all concerned about deployment, I could barely write html never mind get the thing running on an actual server. However as time went on I realised that I would have to have a go at getting this deployed out to a running server. This started with a very very manual process. First I had to install all the prerequisites, in this case python 2.7, mysql server, mysql-python connector, django and all those other little good things that it needed to run.

After that it's a matter of getting the code on the machine. For this I had a bunch of hand cranked scripts which replied heavily on ssh keys on my local machine to do the deployment. Not ideal. This really became apparent when other developers wanted to get in to make some changes. I wanted to remove this reliance on me as a bottle neck for deployments.

Conversion to rpm's

In step rpm's, Red Hats package management system. This was something we'd been trying to investigate in work of how to package our production code so I wanted to see how I could implement this as part of a trail run. This took care of the any scripts that had to run post deployment as all is catered for in the rpm word. A better solution alright however I was still taking the rpm down to my local VM after CI had built it and doing manual testing after an export from the live database.

Automated deployment to a test environment

In order to take me and my lovely VM out of the picture I really needed a test environment where I could tear down the database and recreate as necessary. This meant that I would be able to automatically deploy to this environment when the CI build had completed. A much better solution. In order to do this I had to get a new environment up and running, back to compiling and install python again. To hell with this I said - in order to be able to do this anywhere I really needed packages for all my dependencies as well.

I was much more confident in rpm's now so I created one for all the dependencies also, I now have a python rpm, a mysql-python rpm, a mod_wsgi rpm. All ready to set up on a new environment if I so wish. There was another angle on this as well - any developer could get up and running with a developer environment in no time, assuming they would use Red Hat or one of it's alternatives (CentOS in my case)

Current State

I'm now able to deploy to the test environment my new rpm from the build. I also scripted an export of the database, a fresh if you will before the deployment so that the test database would be as close as possible to live data. This means now more testing on my local VM to make sure that the rpm and deployment is up to scratch.

Next Steps

What now. Testing that's what. And lots of it. I'm of the opinion that in order for me to get to the point where I'm able to click the button to deploy to live, i.e. that I've deployed to the test environment and am able to test the change I need a bunch of integration tests. Something that I didn't do well in the first line of development, yes to my shame I cut some corners on the testing front.

I'm really feeling the pain of this architectural blunder now. I have very little confidence in what I add into the app will not regress some other part of it. The technical debt that I have to pay down is quite substantial on this front. There was a second side affect to this I didn't think of either. A social get out clause that other developers were able to see that I hadn't put effort into proper testing and were able to not bother with it themselves, further increasing the technical debt within the application.

Definitely the lessons learned here are that testing, while not an immediate concern at the time of writing the application, is key to be able to take the human out of the picture. I now have a deeper respect when jumping into writing a part of an application to the tests that need to be in place to support the change that I'm making and the resultant lack of confidence in my change if this is not done at the start.

Testing through your home firewall router

Recently I came across a problem where I needed to test a hosted service getting access to a port on my laptop. The general workflow was that I would initiate the request from the hosted service which would then talk to a service running on a tomcat on my local laptop.

There are a number of problems to get around when attempting to do this. First you can't just use your IP address as you see it on a command prompt ipconfig or ifconfig. The network address that you see here is the internal address that your home router has given you and any device connected to it. Therefore the hosted service isn't going to have a clue how to get to 192.168.0.*

What you need here is the external IP address from your home router. There are a number of ways to get this, including some websites that will display it for you but I went to the source - the router. Luckily there was a configuration page which told me the external IP that my router was using.

The next problem is your firewall. Most modern routers come with a firewall - for good reason - to stop those nasties from getting in to your local network. For this test I was testing for a short time so I was happy to bore a hole through my firewall to my local computer IP through port forwarding. This is where you select a port on the router and a port on your laptop and any traffic hitting your router via it's external IP will be forwarded to that port on your laptop through it's local network IP.

In my case I just forwarded port 80 to port 80 (the default) as I was able to set up my service on my local laptop on that port. So after all this was done I was ready to test. Initiating the test from the hosted service still did not work however...ragin.

The final thing that you need to complete is to turn off your windows firewall (if you're running windows). Since I had already let the traffic through the router it was the windows firewall that was blocking the traffic.

Very happy with myself for actually getting that done as I've never tried it before. Good fun.

Oh and yes, I did quickly turn on my firewall again after the testing was complete and remove the port forwarding!