четверг, 2 августа 2012 г.

CI and msdeploy: I want to parameterize my package

When we deploy to different environments, we’d like to have different configuration values to be set during deployment. Some of them (like connection strings) can be parameterized by msdeploy itself when it creates deployment package, but that’s only part of the story. Say we want some values in web.config to be changed depending on environment we’re deploying to. Good news: msdeploy has a mechanism called ‘deployment parameters’ – you can supply a file declaring these parameters and msdeploy will parameterize your package (this is not the same as web.config transformation – a good overview of difference can be found here). Bad news: there’s no UI in Visual Studio that allows you to either specify these parameters or specify a file where they are declared. In case you decide to build deployment package on your own (by invoking msdeploy directly of from an msbuild script) you will face another problem: you can either supply deployment parameters declaration in xml file or have msdeploy gather/discover them – but not both. So you can’t define some of the parameters in a file and let msdeploy do the rest of the job for you. This comes especially inconvenient when you have a database deployment [sql] scripts in your package – in order for msdeploy to pick them up [when invoked from command line] you have to do a lot of plumbing around declaration and command-line arguments. From the other side, when msdeploy gathers parameters on its own, it tends to parameterize things that you might not want to be parameterized (like IIS application name or application pool name).

This is how it can be solved:
1) When Visual Studio creates a deployment package for your application it looks for [YourWebProjectName].wpp.targets file and imports it into running msbuild script (well, it is actually Microsoft.Web.Publishing.targets which looks for and imports this file in case it exists). This little file lets you extend / influence package building pipeline.
2) EnablePackageProcessLoggingAndAssert msbuild parameter allows you to see extended log of what happens when a deployment package is build for your project – by examining this you can discover a set of msbuild targets that can give you a clue on what to extend/precede.
3) DisableAllVSGeneratedMSDeployParameter – allows you to prevent VS from parameterizing your package (so you don’t have duplicate / unnecessary parameters).
4) ParametersXMLFiles item type allows you to supply your own parameters declaration file (you have to put it inside ItemGroup element and reference a file with parameters declaration).
5) When defining you own target, you can hook on a ‘standard’ one (i.e. the one, defined in Microsoft.Web.Publishing.targets) by using either of the following attributes: BeforeTargets, AfterTargets – they contain a coma-separated list of targets you want to hook on.


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