Always download map from blob

Earlier the map was downloaded to a local file and then read.
This lead to an issue when hosting the backend in aurora where it was
a readonly file system. This fix makes it so that the image is read
directly into memory before being passed to the frontend.

backend/Dockerfile

@@ -12,9 +12,7 @@ RUN dotnet publish -c release -o /app
 FROM mcr.microsoft.com/dotnet/aspnet:6.0
 WORKDIR /app
 COPY --from=build /app ./
-
-# Create folder for temporary storing of maps
-RUN mkdir -p /app/Database/Maps/
+RUN apt-get update && apt-get install -y apt-utils libgdiplus libc6-dev
 
 EXPOSE 8000
 

backend/api.test/Mocks/MapServiceMock.cs

@@ -1,4 +1,6 @@
 using System.Collections.Generic;
+using System.Drawing;
+using System.IO;
 using System.Threading;
 using System.Threading.Tasks;
 using Api.Database.Models;
@@ -14,10 +16,11 @@ public async Task<MissionMap> AssignMapToMission(string assetCode, List<PlannedT
             return new MissionMap();
         }
 
-        public async Task<string> FetchMapImage(string missionId)
+        public async Task<Image> FetchMapImage(string missionId)
         {
             await Task.Run(() => Thread.Sleep(1));
-            return "filepath";
+            string filePath = Directory.GetCurrentDirectory() + "Images/MockMapImage.png";
+            return Image.FromFile(filePath); ;
         }
     }
 }

backend/api/Controllers/MissionController.cs

@@ -91,9 +91,11 @@ public async Task<ActionResult<byte[]>> GetMap([FromRoute] string id)
     {
         try
         {
-            string filePath = await _mapService.FetchMapImage(id);
-            var returnFile = PhysicalFile(filePath, "image/png");
-            return returnFile;
+            var mapImage = await _mapService.FetchMapImage(id);
+
+            using var memoryStream = new MemoryStream();
+            mapImage.Save(memoryStream, mapImage.RawFormat);
+            return File(memoryStream.ToArray(), "image/png");
         }
         catch (Azure.RequestFailedException)
         {

backend/api/Services/MapService.cs

@@ -1,4 +1,5 @@
-using System.Globalization;
+using System.Drawing;
+using System.Globalization;
 using Api.Database.Context;
 using Api.Database.Models;
 using Api.Options;
@@ -13,7 +14,7 @@ namespace Api.Services
 {
     public interface IMapService
     {
-        public abstract Task<string> FetchMapImage(string missionId);
+        public abstract Task<Image> FetchMapImage(string missionId);
         public abstract Task<MissionMap> AssignMapToMission(
             string assetCode,
             List<PlannedTask> tasks
@@ -26,8 +27,6 @@ public class MapService : IMapService
         private readonly IOptions<AzureAdOptions> _azureOptions;
         private readonly IOptions<MapBlobOptions> _blobOptions;
         private readonly FlotillaDbContext _dbContext;
-        private readonly string _localFilePath =
-            Directory.GetCurrentDirectory() + "/Database/Maps/map.png";
 
         public MapService(
             ILogger<MapService> logger,
@@ -42,7 +41,7 @@ FlotillaDbContext dbContext
             _dbContext = dbContext;
         }
 
-        public async Task<string> FetchMapImage(string missionId)
+        public async Task<Image> FetchMapImage(string missionId)
         {
             var currentMission = _dbContext.Missions.Find(missionId);
             if (currentMission == null)
@@ -130,22 +129,15 @@ private BlobContainerClient GetBlobContainerClient(string asset)
             return containerClient;
         }
 
-        private async Task<string> DownloadMapImageFromBlobStorage(Mission currentMission)
+        private async Task<Image> DownloadMapImageFromBlobStorage(Mission currentMission)
         {
             var blobContainerClient = GetBlobContainerClient(
                 currentMission.AssetCode.ToLower(CultureInfo.CurrentCulture)
             );
             var blobClient = blobContainerClient.GetBlobClient(currentMission.Map.MapName);
-            try
-            {
-                await blobClient.DownloadToAsync(_localFilePath);
-            }
-            catch (RequestFailedException e)
-            {
-                _logger.LogError("Directory not found: {message}", e.Message);
-                throw e;
-            }
-            return _localFilePath;
+
+            using var stream = await blobClient.OpenReadAsync();
+            return Image.FromStream(stream);
         }
 
         private Boundary ExtractMapMetadata(BlobItem map)