Quick start to C# .NET Core with MongoDB in Docker

All the times I've worked with MongoDB it's been on existing projects. I didn't have to think about the initial setup. I had a rough idea, but I would like to know more.

Being brutally honest with myself, I'm not particularly familiar with how the code side of things hang together either. I'm comfortable querying data, and adding a new property to an existing domain model. But that's quite different to starting a new project.

As I've learned, reading about something and actually doing it are worlds apart. So I wanted to dig a little deeper without installing lots of software. Docker to the rescue.

Docker Compose

Unsuprisingly, someone has thought about and solved this problem for me already. So I did the following:

1. Made a new directory on my hard drive
2. Created a new file called docker-compose.yml and pasted in the yaml from https://hub.docker.com/_/mongo/
3. Ran docker-compose up -d

We're living in the future, as I now have two containers running. 1 with MongoDB listening on port 27017. Another with mongo-express (a web based administration UI at http://localhost:8081/), talking to the first:

C:\> docker ps
CONTAINER ID        IMAGE               COMMAND                  CREATED             STATUS              PORTS                      NAMES
84d560398e0f        mongo               "docker-entrypoint.s…"   2 days ago          Up 2 days           0.0.0.0:27017->27017/tcp   mongodb_mongo_1
21fd00de630e        mongo-express       "tini -- /docker-ent…"   2 days ago          Up 2 days           0.0.0.0:8081->8081/tcp     mongodb_mongo-express_1

Persistant Storage

If you're not worried about the data, you can skip this bit. I wanted to keep the files Mongo creates, so added a volume to my docker-compose.yml file:

    ports:
        - 27017:27017
    volumes:          - C:\MongoDb\data:/data/db    environment:

Mongo Shell

Again, you may not need this part, especially with mongo express. But if you need to use the mongo shell, you can connect to the container and run bash. The credentials from the docker-compose file make the command:

    docker exec -it mongodb_mongo_1 bash
    mongo -u root -p example

.NET Core console app

To make sure we can talk to it programaticaly, I created a not safe for production console app with:

    mkdir console
    dotnet new console
    cd console
    dotnet add Console.csproj package MongoDB.Driver

And put the following in program.cs:

using MongoDB.Bson;
using MongoDB.Driver;

namespace Console
{
    class Sample
    {
        public ObjectId Id { get; set; }
        public string Value { get; set; }
    }

    class Program
    {
        static void Main(string[] args)
        {
            var client = new MongoClient($@"mongodb://root:example@localhost:27017");
            var database = client.GetDatabase("SampleDb");
            var collection = database.GetCollection<Sample>("SampleDb");

            collection.InsertOne(new Sample
            {
                Value = "SampleValue"
            });

            System.Console.WriteLine("Done");
        }
    }
}

Once you run that, use mongo express to confirm you have a new record.

Conclusion

I'm now free to explore and play with Mongo locally and I haven't had to install a thing.

Now that I've done this once, providing I had a fast enough internet connection, I think it would be possible to go from nothing, to a working local development environment within 15 minutes.