![\"Architecture](\"\/images\/auto-update-dot-net-applications\/auto-update.webp\")
\n <\/a>\n \n The client application checks for updates by reaching out to a central update server (Cincinnati Server shown in green above). Cincinnati pulls the metadata stored in a docker registry, builds, and returns a DAG (directed acyclic graph) repesenting the upgrade paths along with metadata. The client application (shown in orange) uses this graph to determine if an upgrade is available. Using the upgrade metadata, the client downloads and launches the installer to start the upgrade process.<\/p>\n\n
What constitutes a release?<\/h1>\n\n
A release consists of two parts:<\/p>\n
- \n
- Installer<\/em> - The installer should be able to upgrade the application with minimal user input.<\/li>\n
- Release metadata<\/em> - Release metadata is a JSON document that contains:\n
- \n
- Channel of the release, i.e., stable, beta, alpha, fast ring etc<\/li>\n
- Platform<\/li>\n
- Weblink to the installer<\/li>\n
- The version of the installer<\/li>\n
- Upgrade paths<\/li>\n
- Any other metadata needed for the upgrade process such as \u201chave the T&C changed requiring the user consent\u201d, \u201ctype of release\u201d and so on<\/li>\n <\/ul>\n <\/li>\n<\/ol>\n\n
An example release metadata for version 1.1.0 of an application will be:<\/p>\n
{<\/span>\n\t<\/span>\"kind\"<\/span>:<\/span> <\/span>\"cincinnati-metadata-v0\"<\/span>,<\/span>\n\t<\/span>\"version\"<\/span>:<\/span> <\/span>\"1.1.0\"<\/span>,<\/span>\n\t<\/span>\"previous\"<\/span>:<\/span> <\/span>[<\/span>\"1.0.0\"<\/span>],<\/span>\n\t<\/span>\"metadata\"<\/span>:<\/span> <\/span>{<\/span>\n <\/span>\"graph.release.channels\"<\/span>:<\/span> <\/span>\"stable\"<\/span>,<\/span>\n <\/span>\"graph.release.arch\"<\/span>:<\/span> <\/span>\"amd64\"<\/span>,<\/span>\n\t\t<\/span>\"kind\"<\/span>:<\/span> <\/span>\"release\"<\/span>\n\t<\/span>}<\/span>\n<\/span>}<\/span>\n<\/span><\/code><\/pre><\/div><\/div>\nThe \u201cprevious\u201d field in the JSON document will determine the versions of the applications that can upgrade to version 1.1.0. The upgrade paths can be controlled using the previous field or the next field as explained here<\/a>.<\/p>\n\n
\u201cgraph.release.channels\u201d is used to indicate the channel (alpha, beta, stable etc) for this release. \u201cgraph.release.arch\u201d is used to indicate the architecture for this release, i.e., amd64, arm, x86 etc. Cincinnati uses these two fields to filter the graph, i.e., a client in the stable channel with amd64 architecture will not receive the upgrade paths for other channels and architectures. You can add more metadata inside the \u201cmetadata\u201d object.<\/p>\n\n
For the sake of simplicity, we will be making use of a single channel. Let us now look at the various components and how we can build\/deploy each.<\/p>\n\n
Part 1 \u2013 Cincinnati Server<\/h1>\n\n
You can find the source code for the Cincinnati server here<\/a> and the docker image here<\/a>. This fork of Cincinnati removes OpenShift specific code.<\/p>\n\n
To run the Cincinnati server, we need a docker repository to store the release metadata. Create a blank repository in the docker registry of your choice and then open a terminal and run the following command to start the Cincinnati server on port 9000.<\/p>\n
docker run -p 9000:9000 -d -e PORT=9000 -e REGISTRY=<<registory-url>> -e REPOSITORY=<<username>>\/<<repository-name>> lalitadithya\/Cincinnati\n<\/code><\/pre><\/div><\/div>\n\nPart 2 \u2013 The .NET Core Application<\/h1>\n\n
The application should upgrade itself after the user has closed the application, similar to Slack and Visual Studio Code. In .NET, we can register an event handler for
AppDomain.CurrentDomain.ProcessExit<\/code> event, and then we can use theProcess<\/code> library to start the installer as shown in the snippet below:<\/p>\nstatic<\/span> bool<\/span> isUpdateAvailable<\/span> =<\/span> false<\/span>;<\/span>\n\nstatic<\/span> void<\/span> Main<\/span>(<\/span>string<\/span>[]<\/span> args<\/span>)<\/span>\n{<\/span>\n AppDomain<\/span>.<\/span>CurrentDomain<\/span>.<\/span>ProcessExit<\/span> +=<\/span> CurrentDomain_ProcessExit<\/span>;<\/span>\n \/\/ process user request and check for updates in the background and download it if it is available<\/span>\n isUpdateAvailable<\/span> =<\/span> true<\/span>;<\/span>\n}<\/span>\n\nprivate<\/span> static<\/span> void<\/span> CurrentDomain_ProcessExit<\/span>(<\/span>object<\/span> sender<\/span>,<\/span> EventArgs<\/span> e<\/span>)<\/span>\n{<\/span>\n if<\/span>(<\/span>isUpdateAvailable<\/span>)<\/span>\n {<\/span>\n Process<\/span>.<\/span>Start<\/span>(<\/span>new<\/span> ProcessStartInfo<\/span>(<\/span>installerLocation<\/span>)<\/span>\n {<\/span>\n UseShellExecute<\/span> =<\/span> true<\/span>\n });<\/span>\n }<\/span>\n}<\/span>\n<\/code><\/pre><\/div><\/div>\n\nTo interact with the Cincinnati server, we can make use of a NuGet package called \u201ccincinnati-client-net\u201d (GitHub<\/a> and nuget<\/a>). This library queries Cincinnati for upgrade paths, and it returns a list of the possible upgrades along with the metadata as a dictionary. The metadata is fetched from the release metadata that we will create in the next step.<\/p>\n
static<\/span> string<\/span> updateServer<\/span> =<\/span> \"localhost:9000\"<\/span>;<\/span>\n\nstatic<\/span> void<\/span> Main<\/span>(<\/span>string<\/span>[]<\/span> args<\/span>)<\/span>\n{<\/span>\n Version<\/span> version<\/span> =<\/span> Assembly<\/span>.<\/span>GetExecutingAssembly<\/span>().<\/span>GetName<\/span>().<\/span>Version<\/span>;<\/span>\n string<\/span> currentVersion<\/span> =<\/span> $\"<\/span>{<\/span>version<\/span>.<\/span>Major<\/span>}<\/span>.<\/span>{<\/span>version<\/span>.<\/span>Minor<\/span>}<\/span>.<\/span>{<\/span>version<\/span>.<\/span>Revision<\/span>}<\/span>\"<\/span>;<\/span>\n\n \/\/ check for updates<\/span>\n CincinnatiClient<\/span> cincinnatiClient<\/span> =<\/span> CincinnatiClientBuilder<\/span>.<\/span>GetBuilder<\/span>()<\/span>\n .<\/span>WithServerUrl<\/span>(<\/span>updateServer<\/span>)<\/span>\n .<\/span>WithReleaseChannel<\/span>(<\/span>\"stable\"<\/span>)<\/span>\n .<\/span>Build<\/span>(<\/span>new<\/span> HttpClient<\/span>());<\/span>\n var<\/span> availableUpgrades<\/span> =<\/span> cincinnatiClient<\/span>.<\/span>GetNextApplicationVersions<\/span>(<\/span>currentVersion<\/span>).<\/span>GetAwaiter<\/span>().<\/span>GetResult<\/span>();<\/span>\n if<\/span>(<\/span>availableUpgrades<\/span>.<\/span>Count<\/span> ==<\/span> 1<\/span>)<\/span>\n {<\/span>\n string<\/span> newVersion<\/span> =<\/span> availableUpgrades<\/span>[<\/span>0<\/span>].<\/span>Version<\/span>;<\/span>\n string<\/span> installerWebLocation<\/span> =<\/span> availableUpgrades<\/span>[<\/span>
- Release metadata<\/em> - Release metadata is a JSON document that contains:\n