Application in Docker container does not save file to docker volume

Question

I am using Docker desktop to develop my application. I have created a "uploadedfiles" docker volume and I am trying to save files to it, from my docker application. When I save a file from my docker application, I see that the file is saved to the "uploadedfiles" folder on my docker container. I am therefore assuming that I am not binding my application container to the created volume in my Dockerfile.Is my assumption correct?

How can I bind my application container to the created volume in my Dockerfile?

Dockerfile:

FROM mcr.microsoft.com/dotnet/aspnet:5.0 AS base

WORKDIR /app
EXPOSE 80
EXPOSE 443

FROM mcr.microsoft.com/dotnet/sdk:5.0 AS build
WORKDIR /src
COPY ["InstaTranscribeServerSide/InstaTranscribeServerSide.csproj", "InstaTranscribeServerSide/"]
COPY ["Services/Services.csproj", "Services/"]
COPY ["DataAccess/DataAccess.csproj", "DataAccess/"]
RUN dotnet restore "InstaTranscribeServerSide/InstaTranscribeServerSide.csproj"
COPY . .
WORKDIR "/src/InstaTranscribeServerSide"
RUN dotnet build "InstaTranscribeServerSide.csproj" -c Release -o /app/build

FROM build AS publish
RUN dotnet publish "InstaTranscribeServerSide.csproj" -c Release -o /app/publish

FROM base AS final
VOLUME CREATE uploadedfiles
WORKDIR /app
COPY --from=publish /app/publish .
ENTRYPOINT ["dotnet", "InstaTranscribeServerSide.dll"]

Docker Volume does not show uploaded files

Container shows that the volume was not "bound"

Container shows file was uploaded to "uploadedfiles" folder on container:

Volumes are bound to a container at *runtime*. How are you running the container? Have you tried to bind a volume to it? There's plenty of information on how to do that on the web and SO. — JohnXF, Jan 05 '22 at 08:19
I am using Caprover to run the container, I have checked and Caprover has support for persistent apps, so I should be good. https://caprover.com/docs/persistent-apps.html — Ajit Goel, Jan 05 '22 at 17:59

score 0 · Answer 1 · answered Jan 11 '22 at 12:30

I have successfully mount /home/ folder of my host to the /mnt folder of the existing (not running) container. You can do it in the following way:

Open configuration file corresponding to the stopped container, which can be found at /var/lib/docker/containers/99d...1fb/config.v2.json (may be config.json for older versions of docker).

Find MountPoints section, which was empty in my case: "MountPoints":{}. Next replace the contents with something like this (you can copy proper contents from another container with proper settings):

"MountPoints":{"/mnt":{"Source":"/home/<user-name>","Destination":"/mnt","RW":true,"Name":"","Driver":"","Type":"bind","Propagation":"rprivate","Spec":{"Type":"bind","Source":"/home/<user-name>","Target":"/mnt"},"SkipMountpointCreation":false}}
or the same (formatted):

  "MountPoints": {
    "/mnt": {
      "Source": "/home/<user-name>",
      "Destination": "/mnt",
      "RW": true,
      "Name": "",
      "Driver": "",
      "Type": "bind",
      "Propagation": "rprivate",
      "Spec": {
        "Type": "bind",
        "Source": "/home/<user-name>",
        "Target": "/mnt"
      },
      "SkipMountpointCreation": false
    }
  }

Restart the docker service: service docker restart This works for me with Ubuntu 18.04.1 and Docker 18.09.0

Application in Docker container does not save file to docker volume

1 Answers1