Azure Search SDK in Government

So I’ve been working on a demo project using Azure Search, and if you’ve followed this blog for a while, you know. I do a lot of work that requires Azure Government. Well, recently, I needed to implement a search that would be called via an Azure Function and require the passing of latitude and longitude to facilitate the searching within a specific distance. So I started to build my Azure function using the SDK. And what I ended up with looked a lot like this...

Key Data Elements

First, to be able to interact with my search service, I need to install the following nuget package:

Microsoft.Azure.Search

And upon doing so, I found pretty good documentation here for building the search client. So I built out a GeoSearchProvider class that looked like the following:

NOTE: I use a custom class called IConfigurationProvider which encapsulates my configuration store, in most cases its KeyVault, but it can be a variety of other options.

public class GeoSearchProvider : IGeoSearchProvider
    {
        IConfigurationProvider _configurationProvider;

        public GeoSearchProvider(IConfigurationProvider configurationProvider)
        {
            _configurationProvider = configurationProvider;
        }

        public async Task<DocumentSearchResult<SearchResultModel>> 
               RunSearch(string text, string latitude, string longitude, 
               string kmdistance, Microsoft.Extensions.Logging.ILogger log)
        {
            if (String.IsNullOrEmpty(kmdistance))
            {
                kmdistance = await _configurationProvider.GetSetting("SearchDefaultDistance");
            }

            var serviceName = await _configurationProvider.GetSetting("SearchServiceName");
            var serviceApiKey = await _configurationProvider.GetSetting("SearchServiceApiKey");
            var indexName = await _configurationProvider.GetSetting("SearchServiceIndex");

            SearchIndexClient indexClient = new SearchIndexClient
                (serviceName, indexName, new SearchCredentials(serviceApiKey));

            var parameters = new SearchParameters()
            {
                Select = new[] { "...{list of fields}..." },
                Filter = string.Format("geo.distance(location, 
                    geography'POINT({0} {1})') le {2}", latitude, longitude, kmdistance)
            };

            var logmessage = await _configurationProvider.GetSetting("SearchLogMessage");

            try
            {
                var results = await indexClient.Documents.SearchAsync<SearchResultModel>
                              (text, parameters);

                log.LogInformation(string.Format(logmessage, text, latitude, 
                                   longitude, kmdistance, results.Count.ToString()));

                return results;
            }
            catch (Exception ex)
            {
                log.LogError(ex.Message);
                log.LogError(ex.StackTrace);
                throw ex;
            }
        }
    }

The above code seems pretty straight forward and will run just fine to get back my search results. I even built in logic so that if I don’t give it a distance, it will take a default from the configuration store, pretty slick.

And I pretty quickly ran into a problem, and that error was “Host Not found”.

And I racked my brain on this for a while before I discovered the cause. By default, the Azure Search SDK talks to Commercial. Not Azure Government, and after picking through the documentation, I found this. There is a property called DnsSuffix, which allows you to put in the suffix used for finding the search service. By default, it is “search.windows.net”. I changed my code to the following:

public class GeoSearchProvider : IGeoSearchProvider
    {
        IConfigurationProvider _configurationProvider;

        public GeoSearchProvider(IConfigurationProvider configurationProvider)
        {
            _configurationProvider = configurationProvider;
        }

        public async Task<DocumentSearchResult<SearchResultModel>> 
          RunSearch(string text, string latitude, string longitude, string kmdistance, 
          Microsoft.Extensions.Logging.ILogger log)
        {
            if (String.IsNullOrEmpty(kmdistance))
            {
                kmdistance = await _configurationProvider.GetSetting("SearchDefaultDistance");
            }

            var serviceName = await _configurationProvider.GetSetting("SearchServiceName");
            var serviceApiKey = await _configurationProvider.GetSetting("SearchServiceApiKey");
            var indexName = await _configurationProvider.GetSetting("SearchServiceIndex");
            var dnsSuffix = await _configurationProvider.GetSetting("SearchSearchDnsSuffix");

            SearchIndexClient indexClient = new SearchIndexClient
                 (serviceName, indexName, new SearchCredentials(serviceApiKey));
            indexClient.SearchDnsSuffix = dnsSuffix;

            var parameters = new SearchParameters()
            {
                Select = new[] { "...{list of fields}..." },
                Filter = string.Format("geo.distance
                (location, geography'POINT({0} {1})') le {2}", latitude, longitude, kmdistance)
            };

            //TODO - Define sorting based on distance

            var logmessage = await _configurationProvider.GetSetting("SearchLogMessage");

            try
            {
                var results = await indexClient.Documents.SearchAsync<SearchResultModel>
                              (text, parameters);

                log.LogInformation(string.Format(logmessage, text, latitude, 
                                   longitude, kmdistance, results.Count.ToString()));

                return results;
            }
            catch (Exception ex)
            {
                log.LogError(ex.Message);
                log.LogError(ex.StackTrace);
                throw ex;
            }
        }
    }

And set the “SearchSearchDnsSuffix” to “search.azure.us” for government, and it all immediately worked.