- Part 1: Server Core, Containers and Setting Up a Base OS Image (this post)
- Part 3: Deploy an MVC Web Application to a Container
In an older post on website performance using concatenating and minification I used the Ajax Minifier tool to do the work and used an MSBuild file to run that tool, now I use gulp which I find easier as it only needs a dependency on node and so can be separated out from the Visual Studio project itself and run outside the build cycle.
When run in a CI/CD environment, the gulp file is processed before an actual build takes place, this is so that the AssemblyInfo.cs file can be amended with the version information. The gulp file can be broken down into 3 main parts; the version, concatenation and minification and the assembly version writing.
It is real easy to include a gulp task to TeamCity by creating a Build step to your pipeline and choosing the Command Line as the runner type.
Then specify ‘Custom script’ from the drop down and enter your normal gulp command in the Custom script text area.
Foggy Software DevelopmentSoftware development is one of those areas that it is important to find the fine line between too little specification and too much. One project I worked on recently for a client had tremendous success mainly due to good user story development and a good development team that could take those stories and run with them.
This was an agile shop that used the agile template in TFS but also used the vocabulary of scrum interchangeably. Nothing wrong with that, I believe there has to be a balance between adapting your process to your environment as opposed to changing your environment to fit the process especially in larger more traditional businesses. So they had sprints, sprint planning but also user stories as opposed to product backlog items. So six months into the project and all sprints were on the line of the burn-down chart, then things started to go wrong. The burn-down chart was way off with the resources we had at hand, the reason? Well we started to get user stories such as this:-
Story title: We need a different view of the data
Description: To doOr
Story title: General printing
Description: To doThere isn't much you can do with these, but they were in the sprint. The more time a developer spends going to ask for clarification about a user story, the less effort they can put into acting on the story. The end result after all the backwards and forwards communication is an inaccurate burn-down which can lead to a demoralised team and possible infighting. Why were these in the sprint you may ask? Well for some unknown reason, management decided to take a more hands on approach to the project and so forced stories into sprints instead of the software development team deciding what resources were available to tackle the high priority stories. The stories had to be done in that sprint even if the resource was not enough to cover it. Add to that, the management only had a vague idea of what those stories were and possibly due to lack of time couldn't expand on their details.
So what is just enough information for a user story?
- The product owners should define the features of the project.
- The business analyst and business owners should define the user stories that lead to the features and describe the acceptance criteria to fulfil the user story.
- The development team should create the tasks off the user stories that will fulfil the acceptance criteria and make the user story valid.
Part 2 - Securing Web.API Requests With JSON Web Tokens (This post)
In the last post I went over the techniques you can use to secure your ASP.Net MVC logins using salted hashes in the database. This post covers the web service layer and how to secure requests to service calls that are essentially exposed to the big bad web. To show what sort of layering I am discussing, here is a basic example of the various layers I have been using on a number of projects.
Once the user has been validated and allowed into the site, all service requests are done on their behalf. To make sure nobody who is not validated get access to the service calls, we implement JSON Web Tokens or JWT.
JSON Web TokensJason Web Tokens are a standard and url safe way of representing claims and was created by the Internet Engineering Task Force (IETF). They are in the form like this:-
A JWT is split into 3 sections which comprise of:-
JOSE Header - this describes the token and the hashing algorithm that is being used for it.
JWS Payload - the main content and can include claims sets, issuer, expiry date as well as any bespoke data you want to include
Signature hash - base64 encoding the header and payload and creating the message authentication code (MAC) leads to the signature hash
Creating JSON Web Tokens in .NetGoing back to the web project, in the constructor of each controller, create a private field that will store our token string.The code to generate the token uses the System.IdentityModel.Tokens.Jwt namespace which you may need to add extra references for by using the NuGet packages.The call to Authorization.GetBytes() is a method call from a class we use in a business object that sits in the Webservice layer. All it does is turns a string into a byte array.Here we just store the web token in the viewbag for rendering on each view, the reason we do this is because we don't want to run into any cross domain issues as our web and web service layers are running on different machines on different urls.Now in the angular code that is calling into the service layer we extract that token and append it to the call as a parameter.
Consuming JSON Web TokensIn the web service layer we intercept each call by creating an override on the OnAuthorization method inside AuthorizeApi.cs within App_Start.If they have the correct and valid token then they proceed to get the data from the API call, if not they get sent a 403 Forbidden response.
JSON Web Token (JWT) - OAuth Working Group
Part 2 - Securing Web.API Requests With JSON Web Tokens
An archetectural patterns that is becoming more popular is using ASP.Net MVC with a Web.API layer servicing the web front end via angular.js or similar technology. A kind of hybrid SPA with all the benefits that ASP.Net bring to the table. This is a two part primer running through what I do to secure logins to MVC applications. In part two I will expand on this post to cover how to secure the Web.API layer utilizing the security built into ASP.Net.
If you ever go to a web site and you cannot remember your password, you will most likely have requested a password reminder. If you get sent your current password in plain text, then that is bad news. It means the website is storing passwords in plain text and if they get hacked then they will have access to those passwords, and knowing the fact that people have a tendency to use the same password on multiple sites then they could compromise multiple sites that you use. It is really important to salt and hash your passwords for storage in the database. By doing this, you can do a string comparison against the hash and not the actual password. Here I will go through the process in code.
As usual you will have a login screen asking for username (or email address) and password. I won't go into the MVC/Razor side here, just the important code.
Take in the two form values
The LookupUser method on the SecurityService is where the magic happensThis method looks up the User from the database via a UserRepository and appends the salt to the password the user has provided. I explain what salts and hashes are a little later on, but for now know they are just a random string representation of a passkey. This combination of password and salt are then passed into the GetPasswordHashAndSalt method of the PasswordHash class.The GetPasswordHashAndSalt method reads the string into a byte array and encrypts it using SHA256, then returns a string representation of it back to the calling method. This is then the hash of the salted password which should be equal to the value in the database. On line 19 of the SecurityService class the repository does another database look-up to get the User that matches both the email address and hash value. OK, so how do we get those hashes and salts in the database in the first place? When a new user account is set up you need to generate a random salt like this:-You then store the usual user details in the database along with the salt and the hashAndSalt values in place of the password. By generating a new salt each time an account is created you minimize the risk that a hacker will get the salt and regenerate the passwords from the hashAndSalt value. Now back to the login POST method on the controller. Once the user has been authenticated in the system, you need to create a cookie for the ASP.Net forms authentication to work. First create a ticket that stores information such as the user logged in.Where LoggedInUser is the valid User object we got from the database earlier. To check for a valid ticket throughout the site, you can decorate each action method with [Authorize] filter attributes, or you could do the whole site and just have [AllowAnonymous] attributes on the login controller actions. To do this for the whole site firstly add a new AuthorizeAttribute to the FilterConfig.cs file inside App_Start like this:-Then in the Application_AuthenticateRequest method to the global.asax.cs file add this:-This method will check every request coming in to see if it has a valid FormsAuthentication ticket. If it doesn't then it will redirect the user to the default location specified in the web.config file.