csharp-kestrel-mongo

This repository is for the csharp-kestrel-mongo OpenFaas function template.

The function template provides the functionality to be able to communicate to a Mongo database. It will also cache the connection therefore all successive calls to Mongo after the first will not cold start. The function template also provides some useful extention methods that can be used within the function handler:

this.GetCollection(); | Gets the mongo collection typically used for CRUD operations.
this.GetDatabase();   | Gets the mongo databased used for interfacing with the database.

The function handler where all the logic is done looks as follows:

public class FunctionHandler
{
    public async Task<string> Handle(object input)
    {
        // Inserts the input into the mongodb collection as a bson document.
        await this.GetCollection()
                  .InsertOneAsync(input.ToBsonDocument());

        // Cannot change status code in http response: https://github.com/openfaas/faas/issues/157
        // Suggested to add status code in body response
        var response = new ResponseModel()
        {
            response = input,
            status = 201
        };
        
        // Returns the response as Json.
        return JsonConvert.SerializeObject(response);
    }
}

To use the template the following instructions can be followed:

faas-cli template pull https://github.com/Marcus-Smallman/csharp-kestrel-mongo.git

faas-cli new mongo-function --lang csharp-kestrel-mongo

The template uses the following environment variables:

Envrionment Variable	Example	Required
mongo_endpoint	mongo_endpoint: localhost:27017	yes
mongo_database_name	mongo_database_name: my_mongo_database	no
mongo_collection_name	mongo_collection_name: my_mongo_collection	no

If the mongo_database_name is not provided the database name will default to: default_database

If the mongo_collection_name is not provided the collection name will default to: default_collection

An example of a stack used to build and deploy the mongo function:

provider:
  name: faas
  gateway: http://127.0.0.1:8080

functions:
  mongo-function:
    lang: csharp-kestrel-mongo
    handler: ./mongo-function
    image: <docker-registry>/mongo-function
    environment:
      mongo_endpoint: localhost:27017
      mongo_database_name: my_mongo_database
      mongo_collection_name: my_mongo_collection

The following environment variables can also be set if the connection between the function and mongo is slow on intial start:

read_timeout: 20
write_timeout: 20

This sets the read and write timeout to 20 seconds.

The function can then be deployed:

  faas-cli build -f mongo-function.yml
  faas-cli push -f mongo-function.yml
  faas-cli deploy -f mongo-function.yml

Once deployed the functions can be invoked:

"This will be added into mongo" | faas-cli invoke -f mongo-function.yml mongo-function

Notes

MongoDB driver used for this template is: 2.3.0

Supported architecture(s): x86_64, armhf