public async IAsyncEnumerable <IntegrationRegistration> GetIntegrations()
{
var rootDirectory = Path.GetFullPath(this.Configuration.GetValue <string>("Mifs:IntegrationPath"));
var integrationRegistrations = new List <IntegrationRegistration>();
var configurationFilesByDirectory = Directory.EnumerateFiles(rootDirectory, "*appsettings.json", SearchOption.AllDirectories)
.GroupBy(file => Path.GetDirectoryName(file));
foreach (var configurationFiles in configurationFilesByDirectory)
{
var directory = Path.GetFullPath(configurationFiles.Key !);
var configuration = this.BuildConfigurationForIntegration(configurationFiles);
var integrationConfiguration = configuration.GetSection("Integration")
.Get <IntegrationConfiguration>();
if (!this.IsIntegrationConfigurationValid(integrationConfiguration))
{
this.Logger.LogWarning("Failed to register Integration in directory '{directory}' because it was invalid. Check its configuration contains the Integration Name and Entry Assembly.", directory);
continue;
}
this.Logger.LogInformation("Found Integration {integrationName} in directory {directory}.", integrationConfiguration.Name, directory);
var integrationRegistration = new IntegrationRegistration(directory, configuration);
yield return(integrationRegistration);
await Task.Yield();
}
}
public void Register(IntegrationRegistration integrationRegistration)
{
var integrationName = integrationRegistration.Name;
if (this.TryGetRegistration(integrationName, out var existingRegistration))
{
if (existingRegistration is not null && integrationRegistration.Directory != existingRegistration.Directory)
{
this.Logger.LogWarning("Trying to register {integrationName} from directory {newDirectory} but it is already registered for directory {existingDirectory}. If you intended to change the directory deregister the old one first.",
integrationName, integrationRegistration.Directory, existingRegistration.Directory);
}
else
{
this.Logger.LogInformation("Attempted to register {integrationName} but it is already registered.", integrationName);
}
return;
}
private async Task <IntegrationHostData> CreateAndStartIntegrationHost(ICacheEntry cacheEntry, IntegrationRegistration integrationRegistration, CancellationToken cancellationToken = default)
{
if (cancellationToken.IsCancellationRequested)
{
return(new IntegrationHostData(null, HostStatus.Errored)
{
Message = "Startup cancelled."
});
}
// Pull a fresh copy of the IntegrationConfiguration to do some validation
var integrationConfiguration = integrationRegistration.IntegrationConfiguration;
var integrationName = integrationConfiguration.Name;
var entryAssembly = integrationConfiguration.EntryAssembly;
if (integrationName is null)
{
return(new IntegrationHostData(null, HostStatus.Errored)
{
Message = "Integration Name not set properly in configuration."
});
}
if (entryAssembly is null)
{
return(new IntegrationHostData(null, HostStatus.Errored)
{
Message = "Entry assembly not set properly in configuration."
});
}
if (!integrationConfiguration.IsEnabled)
{
this.Logger.LogInformation("Did not start {integrationName}. The Integration is currently disabled.", integrationName);
return(new IntegrationHostData(null, HostStatus.Disabled));
}
var entryAssemblyPath = Path.Combine(integrationRegistration.Directory, entryAssembly);
if (!File.Exists(entryAssemblyPath))
{
this.Logger.LogError("Failed to Start {integrationName} because the entry assembly {entryAssemblyPath} could not be found", integrationName, entryAssemblyPath);
return(new IntegrationHostData(null, HostStatus.Errored)
{
Message = $"Failed to Start integration {integrationName} because the entry assembly {entryAssemblyPath} could not be found"
});
}
// Use a custom Assembly load context to allow each Host to use its own dependencies.
// If a custom dependency is not defined in the same folder, it will fallback to using any Assemblies loaded in the default context.
// The only requirement is that the Mifs.dll cannot be different because that would result in different instances of IInitializationInstance's
// making FindAndCreateIntegrationInitializationInstance never find a type to instantiate.
var assemblyLoadContext = new IntegrationAssemblyLoadContext(integrationRegistration.Directory);
var bootstrapInstance = this.FindAndCreateIntegrationBootstrapInstance(entryAssemblyPath, AssemblyLoadContext.Default);
if (bootstrapInstance is null)
{
return(new IntegrationHostData(null, HostStatus.Errored)
{
Message = ""
});
}
var host = await this.IntegrationHostFactory.CreateAndStart(bootstrapInstance, integrationRegistration.Configuration, cancellationToken);
if (host is null)
{
return(new IntegrationHostData(host, HostStatus.Errored)
{
Message = $"Host failed to create"
});
}
// Make sure that when the host is shut down the assembly load context gets unloaded.
var applicationLifetime = host.Services.GetRequiredService <IHostApplicationLifetime>();
applicationLifetime.ApplicationStopping.Register(() => assemblyLoadContext.Unload());
cacheEntry.RegisterPostEvictionCallback(this.OnCacheEntryEvicted);
this.Logger.LogInformation("{integrationName} Started.", integrationName);
return(new IntegrationHostData(host, HostStatus.Started));
}
