{"componentChunkName":"component---src-templates-tags-js","path":"/tags/emulator/","result":{"data":{"allMarkdownRemark":{"totalCount":2,"edges":[{"node":{"id":"d37ae6d6-4052-59c9-85a3-c0540c354135","html":"

Azure Cosmos DB is one of the foundational services in Azure, which provides high availability, global scale and an impressive performance. However, it could be a bit costly for developers to spin up an instance during their development especially if they don’t know some of the basics such as what should be the partition key, what throughput they should select and so on that much.

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The Azure Cosmos DB Emulator is a service provided by Microsoft which allows you to emulate the Cosmos DB Service locally for development purposes. In addition, no matter whether you’re using Azure CosmosDB or not, at some point you might have to test some sort of DocumentDB locally.

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Intro

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Let’s be honest, there are other ways to work with Cosmos DB without paying any money such as a Free Trial Account which gives you $200 dollars to spend over a year, or even the Cosmos DB Query Playground which is an interactive website which helps you to learn the query syntax and provides you with a set of pre-defined JSON documents to work with.

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But eventually you either run out of money, or your product is live and your developers want to develop new features and fix bugs to be released very quickly. That’s when Cosmos DB Emulator really comes to the rescue. You have other advantages such as ability to work offline and or even have an Azure subscription.

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Features

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API set

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Azure Cosmos DB supports SQL API, as well as Table, MongoDB, Cassandra, and Gremlin which to me covers many scenarios from migrating an existing database from on-premise to Azure, modernising your legacy application, or create a brand new one. Azure Cosmos DB Emulator also supports these APIs although the underlying implementation details are different to the real service on Azure. In fact the emulator hides all abstractions from you and lets you focus on adding value to your team or organisation.

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💡 However keep in mind that the data explorer provided with the service only supports SQL API at the moment.

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Number of containers

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The emulator allows you to create a single account with multiple (up to 25 fixed sized, or 5 unlimited) containers.

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Operating System

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At the moment, the emulator only supports 64-bit versions of Windows (Server 2012 R2, Server 2016, Server 2019, Windows 10) which demands a minimum of 2GB of RAM and 10GB of free disk space. You must also have administrative privileges to be able to install the client.

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In addition to that, it also comes with docker image which you can use to run the emulator in a docker container but only on windows containers. If you want to use docker in Linux or macOS, you will need to use it on a Windows virtual machine.

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Installation

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Simply download the executable from here and install it on your Windows OS, if you’re running Linux or macOS or want to run it in a docker container please refer to the official documentation.

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Differences

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As amazing it looks, there are a few differences you need to keep in mind when working with the emulator:

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Summary

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In this short article I just showed you the tip of the iceberg about what the Azure Cosmos DB Emulator has to offer for you. It’s a great utility to be able to develop applications who rely on Azure Cosmos DB locally and has helped me in my pet projects which doesn’t even need to work with a Cosmos DB instance. Keep an eye out for more articles on some use cases this amazing tool can help you with.

","timeToRead":3,"frontmatter":{"title":"How much do you know about Azure CosmosDB Emulator? 🧐","unformattedDate":"2020-12-15T00:00:00.000Z","date":"Dec 15, 2020","path":"/cosmos-emulator/","author":"Yaser Adel Mehraban","tags":["azure","showdev","cosmosdb","emulator"],"thumbnail":null}}},{"node":{"id":"5349daad-655e-579a-967b-7956530dc39e","html":"

I recently was trying to prepare a demo which involved me having a local MongoDb database. I reviewed a few options and was about to choose one when I remembered I have Azure Cosmos DB Emulator installed and Cosmos DB supports MongoDb APIs.

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Install if you haven’t already

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You will need below requirements to be able to install the emulator:

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If you’ve ticked all of above already, then head over here and install the latest version. If you stumbled upon any issues use the troubleshooting guide to find out what’s happening.

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💡 Make sure you check for updates regularly since each new version might contain new features and bug fixes.

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Starting the emulator

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Normally you would use the Windows start menu to find your programs and start the application, however, for the emulator to support MongoDB APIs, you will need to pass the EnableMongoDbEndpoint argument.

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You have a few options here:

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  1. Create a shortcut and pass the required arguments
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  2. Use command line to start it
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I am going to use Windows Terminal. Run the below command to fire up the emulator with MongoDB support:

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& 'C:\\Program Files\\Azure Cosmos DB Emulator\\CosmosDB.Emulator.exe' /EnableMongoDbEndpoint
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You will be prompted to approve the emulator making changes to your system and once approved, you will see the emulator starting and the interface will open in your default browser.

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Getting the connection string

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The very first thing you’d see is the quick start which should look something like this:

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\n \n printed on your console which means you’ve successfully connected to the MongoDb APIs.

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Seed the database

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First let’s create a JSON file which contains some celebrities 😎:

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[{\r\n  \"age\": 18,\r\n  \"birth_place\": \"Harij, Gujarat, India\",\r\n  \"birth_sign\": \"Pisces\",\r\n  \"birth_year\": \"1996\",\r\n  \"birthday\": \"September 28\",\r\n  \"name\": \"Daxeel Soni\",\r\n  \"occupation\": \"Developer of this API. More: www.daxeelsoni.in\",\r\n  \"photo_url\": \"http://daxeelsoni.in/images/me.jpg\"\r\n}, {\r\n  \"age\": 28,\r\n  \"birth_place\": \"Houston\",\r\n  \"birth_sign\": \"Libra\",\r\n  \"birth_year\": \"1987\",\r\n  \"birthday\": \"September 28\",\r\n  \"name\": \"Hilary Duff\",\r\n  \"occupation\": \"TV Actress\",\r\n  \"photo_url\": \"http://www.famousbirthdays.com/thumbnails/duff-hilary-medium.jpg\"\r\n}, {\r\n  \"age\": 38,\r\n  \"birth_place\": \"Columbia\",\r\n  \"birth_sign\": \"Libra\",\r\n  \"birth_year\": \"1977\",\r\n  \"birthday\": \"September 28\",\r\n  \"name\": \"Young Jeezy\",\r\n  \"occupation\": \"Rapper\",\r\n  \"photo_url\": \"http://www.famousbirthdays.com/thumbnails/jeezy-young-medium.jpg\"\r\n}, {\r\n  \"age\": 48,\r\n  \"birth_place\": \"Roanoke\",\r\n  \"birth_sign\": \"Libra\",\r\n  \"birth_year\": \"1967\",\r\n  \"birthday\": \"September 28\",\r\n  \"name\": \"Challen Cates\",\r\n  \"occupation\": \"TV Actress\",\r\n  \"photo_url\": \"http://www.famousbirthdays.com/thumbnails/cates-challen-medium.jpg\"\r\n}]
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Now that we have our JSON file, let’s seed the database. Replace the initial connect code with this:

\n {\r\n MongoClient.connect(\r\n CONNECTION_URL,\r\n {\r\n useNewUrlParser: true,\r\n sslValidate: false,\r\n },\r\n (error, client) => {\r\n if (error) {\r\n throw error;\r\n }\r\n database = client.db(DATABASE_NAME);\r\n collection = database.collection("celebrities");\r\n collection.estimatedDocumentCount({}, (erorr, numOfRecords) => {\r\n if (numOfRecords <= 0) {\r\n fs.readFile("./info.json", "utf8", (err, data) => {\r\n if (err) {\r\n console.log(\\`Error reading file from disk: \\${err}\\`);\r\n } else {\r\n // parse JSON string to JSON object\r\n const celebrities = JSON.parse(data);\r\n\r\n collection.insertMany(celebrities, (error, result) => {\r\n if (error) {\r\n console.log(\\`Error in saving seed data: \\${error}\\`);\r\n }\r\n\r\n console.log(\\`Seed data inserted into the database!\\`);\r\n });\r\n }\r\n });\r\n } else {\r\n console.log(\\`Connected to database\\`);\r\n }\r\n });\r\n }\r\n );\r\n});`, `51705009579308080000`)\"\n >\n \n Copy\n \n \n
app.listen(5000, () => {\r\n  MongoClient.connect(\r\n    CONNECTION_URL,\r\n    {\r\n      useNewUrlParser: true,\r\n      sslValidate: false,\r\n    },\r\n    (error, client) => {\r\n      if (error) {\r\n        throw error;\r\n      }\r\n      database = client.db(DATABASE_NAME);\r\n      collection = database.collection(\"celebrities\");\r\n      collection.estimatedDocumentCount({}, (erorr, numOfRecords) => {\r\n        if (numOfRecords <= 0) {\r\n          fs.readFile(\"./info.json\", \"utf8\", (err, data) => {\r\n            if (err) {\r\n              console.log(`Error reading file from disk: ${err}`);\r\n            } else {\r\n              // parse JSON string to JSON object\r\n              const celebrities = JSON.parse(data);\r\n\r\n              collection.insertMany(celebrities, (error, result) => {\r\n                if (error) {\r\n                  console.log(`Error in saving seed data: ${error}`);\r\n                }\r\n\r\n                console.log(`Seed data inserted into the database!`);\r\n              });\r\n            }\r\n          });\r\n        } else {\r\n          console.log(`Connected to database`);\r\n        }\r\n      });\r\n    }\r\n  );\r\n});
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All we’re doing here is to get the number of records in the collection and if there is nothing, read the JSON file and write it to the collection.

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Don’t forget to add const fs = require('fs') at the top with other require statements.

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Now if you run npm start would should see the application start and then the seed data inserted message.

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Creating the endpoint

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And now all we need is to add our get endpoint to be able to fetch our celebrities. Don’t forget to add it before you create your listener:

\n {\r\n collection.find({}).toArray((error, result) => {\r\n if(error) {\r\n return response.status(500).send(error);\r\n }\r\n response.send(result);\r\n });\r\n});`, `98512496102421050000`)\"\n >\n \n Copy\n \n \n
app.get(\"/api/celebrities\", (request, response) => {\r\n    collection.find({}).toArray((error, result) => {\r\n        if(error) {\r\n            return response.status(500).send(error);\r\n        }\r\n        response.send(result);\r\n    });\r\n});
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Testing the application

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You’re now ready to get your celebrities via the API. Simply open a browser and head over to http://localhost:5000/api/celebrities or just use the below command:

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curl -X GET http://localhost:5000/api/celebrities
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Summary

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In this guide we saw how to use Azure Cosmos DB Emulator with MongoDb API to have a local MongoDb available for our local development and proof of concepts. Hope this has helped you save some time and also the trouble of installing yet another software on your system (of course if you already are using the emulator 😊).

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Enjoy hacking and let us know what awesome projects you’re doing using the emulator.

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PS: You can find the finished code in my GitHub repository here.

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