internal static HostIdResult GetDefaultHostId(IEnvironment environment, ScriptApplicationHostOptions scriptOptions)
{
HostIdResult result = new HostIdResult();
// We're setting the default here on the newly created configuration
// If the user has explicitly set the HostID via host.json, it will overwrite
// what we set here
string hostId = null;
if (environment.IsAppService() || environment.IsKubernetesManagedHosting())
{
string uniqueSlotName = environment?.GetAzureWebsiteUniqueSlotName();
if (!string.IsNullOrEmpty(uniqueSlotName))
{
// If running on Azure Web App, derive the host ID from unique site slot name
hostId = uniqueSlotName;
}
}
else if (environment.IsLinuxConsumption())
{
// The hostid is derived from the hostname for Linux consumption.
string hostName = environment.GetEnvironmentVariable(EnvironmentSettingNames.AzureWebsiteHostName);
hostId = hostName?.Replace(".azurewebsites.net", string.Empty);
}
else
{
// When running locally, derive a stable host ID from machine name
// and root path. We use a hash rather than the path itself to ensure
// IDs differ (due to truncation) between folders that may share the same
// root path prefix.
// Note that such an ID won't work in distributed scenarios, so should
// only be used for local/CLI scenarios.
string sanitizedMachineName = Environment.MachineName
.Where(char.IsLetterOrDigit)
.Aggregate(new StringBuilder(), (b, c) => b.Append(c)).ToString();
hostId = $"{sanitizedMachineName}-{Math.Abs(Utility.GetStableHash(scriptOptions.ScriptPath))}";
result.IsLocal = true;
}
if (!string.IsNullOrEmpty(hostId))
{
if (hostId.Length > ScriptConstants.MaximumHostIdLength)
{
// Truncate to the max host name length
hostId = hostId.Substring(0, ScriptConstants.MaximumHostIdLength);
result.IsTruncated = true;
}
}
// Lowercase and trim any trailing '-' as they can cause problems with queue names
result.HostId = hostId?.ToLowerInvariant().TrimEnd('-');
return(result);
}
public Task <string> GetHostIdAsync(CancellationToken cancellationToken)
{
string hostId = _config[ConfigurationSectionNames.HostIdPath];
if (hostId == null)
{
HostIdResult result = GetDefaultHostId(_environment, _options.CurrentValue);
hostId = result.HostId;
if (result.IsTruncated && !result.IsLocal)
{
_hostIdValidator.ScheduleValidation(hostId);
}
}
return(Task.FromResult(hostId));
}
