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This is a repost that originally appeared on the Couchbase Blog: Azure Functions and Lazy Initialization with Couchbase Server.

Azure Functions are still new to me, and I’m learning as I’m going. I blogged about my foray into Azure Functions with Couchbase over a month ago. Right after I posted that, I got some helpful feedback about the way I was instantiating a Couchbase cluster (and bucket).

I had (wrongly) assumed that there was no way to save state between Azure Function calls. This is why I created a GetCluster() method that was called each time the function ran. But, initializing a Couchbase Cluster object is an expensive operation. The less often you instantiate it, the better.

You can follow along with the updated source code for this blog post on Github.

Static state

I had a hard time finding documentation on whether I could use a static object for reuse between function calls. I suppose I should have experimented, like fellow Microsoft MVP Mark Heath did. Instead, I posed the question to StackOverflow.

In short: yes. A Cluster, instantiated and saved to a static member, can is reusable between function calls. According to Mark’s post above, there’s no guarantee how long this value will survive. But that’s an expected trade-off that you make when going "serverless".

Lazy initializing within Azure Functions

Simply using a static member would work, but it’s not thread-safe. There are a few ways to tackle that issue, but an easy way that’s built right into the .NET framework is to use Lazy Initialization with Lazy<T>.

Lazy Initialization in Azure Functions

First, I removed the GetBucket and GetCluster methods. Next, I created a Lazy<IBucket> property to replace them.

private static readonly Lazy<IBucket> Bucket = new Lazy<IBucket>(() =>
{
    var uri = ConfigurationManager.AppSettings["couchbaseUri"];
    var bucketName = ConfigurationManager.AppSettings["couchbaseBucketName"];
    var bucketPassword = ConfigurationManager.AppSettings["couchbaseBucketPassword"];
    var cluster = new Cluster(new ClientConfiguration
    {
        Servers = new List<Uri> { new Uri(uri) }
    });
    return cluster.OpenBucket(bucketName, bucketPassword);
});

I just made a single property for a bucket, since that’s all I need for this example. But if you need to use the cluster, you can easily make that its own Lazy property. (Once you have a cluster, getting a bucket is a relatively cheap operation).

Using a Lazy property

When you instantiate a Lazy<T> object, you supply it with an initialization lambda. That lambda won’t execute until the Value property is actually called for the first time.

var lazyObject = new Lazy<string>(() =>
{
    // this code won't be called until 'lazyObject.Value' is referenced
    // for the first time
    return "I'm lazy!";
});

For instance, notice the Value between Bucket and GetAsync in the updated version of my Azure Functions:

var doc = await Bucket.Value.GetAsync<MyDocument>(id);

If that’s the first time Value is used, the cluster will be initialized. Otherwise, it will use the already initialized cluster (try experimenting with a Guid instead of a Bucket).

Summary

State can be saved between Azure Function calls by using a static member. Make sure that it’s thread-safe (by using Lazy<T> or something like it). Don’t make any assumptions about how long that object will be around.

Anything else I missed? Are you using Azure Functions with Couchbase? I would love to hear from you. Please leave a comment below or ping me on Twitter @mgroves.

This is a repost that originally appeared on the Couchbase Blog: Azure: Getting Started is Easy and Free.

Azure is where Microsoft is spending a lot of its efforts lately. Microsoft is dedicated to making Azure a success. As someone who started working with Azure a little in the early days, I can say that it’s come a long way, and offers a remarkable set of services at good prices.

But not everyone is on board with Azure or even with cloud computing yet. If you haven’t yet dipped your toe into the Azure pool, but are curious, this blog post is for you.

What is cloud computing? What is Azure?

Cloud computing basically means that instead of running applications in your own data center, you run it in someone else’s data center. Why would I do that?

Running a data center is difficult and expensive. You have to purchase hardware, manage upgrades, security, networking, and even stuff like electricity, ventilation, and cooling. For some enterprises, this is either not a big deal or it’s worth the hassle. But for many enterprises, the value that you’re delivering is not in the hardware or the operating system and so on, but in the domain expertise that goes into the software you’re building. Then, cloud appeals to enterprises who would rather someone else handle all that other stuff.

A metaphor that I really like was written up by Albert Barron in a blog post called Pizza as a Service (I especially like the diagram). It makes sense for a pizza company to control the whole stack because pizza making is their core competency. But if pizza making isn’t your job, it makes sense to take another option, like dining out, so you can instead spend your time focusing on what you do best.

This isn’t to say that cloud is always the best solution, but it explains why many companies are choosing to move at least some of their infrastructure and platform to a cloud provider like Microsoft’s Azure.

How do I sign up for Azure?

If you’re on the fence, I recommend at least giving it a try, so that you’re prepared for the day that your CTO comes to you and asks "so what are we doing about the cloud?"

Signing up for Azure is easy.

Create Microsoft account

To start, you’ll need a Microsoft account. If you don’t already have one, you can signup here. It’s free, and you can use it in a bunch of other places later, even if you end up not liking Azure.

Create a Microsoft account

Create Azure account

Next, go to azure.microsoft.com and create a free account. Signing up with that link will give you $200 in free credit to use on Azure services. You do need to use a credit card to sign up, but it is just for verifying your identity (they don’t want a bunch of spammers and bitcoin bots). Microsoft will not charge you until you say so.

Side note: If you have an MSDN/Visual Studio license, are part of the BizSpark program or have an educational grant through AzureU (ask your professor!), you may already have some free Azure credit on a monthly basis!

Create Azure account

Speaking of money, there are some things you can do in Azure that are absolutely free. But, running Couchbase Server currently requires you to provision Virtual Machines, so if you want to play with Couchbase, you will put that $200 to good use.

Couchbase and Azure: Is $200 enough?

When I first started with Azure, I was very worried that I’d run up a big tab if I wasn’t careful. With the $200 trial, you won’t get charged until you explicitly tell Microsoft to do so. But years later, after my initial trial, I’ve still never had a problem of an unexpectedly high bill.

Quotas

I’ve never had this problem because:

a) Azure services are very reasonably priced, and

b) Microsoft makes it hard to hop on a runaway train of spending money.

In fact, almost a year ago, I was tasked with provisioning a medium-sized cluster of Couchbase nodes on some very beefy Virtual Machines. Lots of RAM, lots of processor cores, 10 total virtual machines all running Couchbase. I started doing this (manually, to begin with) and discovered that Azure actually has a quota that limits the number of cores you can provision. If you want to create a huge Couchbase cluster, you’ll first need to request an increase in the limit on the number of cores and/or virtual machines that you are allowed to have (this is a manual process, again to avoid abuse/surprises/exploitation/etc).

Azure core quota

Because of that, I realized that even if I had created an experimental automated script that I accidentally asked to create 100 machines instead of 10, Azure would stop me.

It cost how much?

Until you want to build that huge cluster, you probably won’t need more than $200 to start with, and you won’t need to increase your quota.

As an example, I ran a single-node Couchbase Server on a low-end virtual machine within the last 30 days. I must have provisioned, used it, and tore it down 3 or 4 times. As you can see from the below screenshot of my billing statement, it cost me a grand total of $0.11 for an hour and a half of VM time (and I think there are a few pennies for related services, not shown).

Azure costs by service

(Some information blurred to protect the innocent).

Your mileage will vary, but my point is that I think you will find it more challenging to use up that $200 credit than you think.

More than enough to get started with Couchbase

Finally, when you’re ready to play around with Couchbase, I encourage you to check out other blog posts about Couchbase Server.

Also, watch this short instructional video on how to provision Couchbase Server clusters automatically. You don’t have to provision a Virtual Machine, install Couchbase, do the initial cluster setup, network them together, etc manually. This video (courtesy of Ben Lackey from the Couchbase Partners team) shows you how to provision a Couchbase Server cluster from the Azure Marketplace.

Summary

If you’ve never used Azure or any cloud computing, now is your chance to get started. I’d love to hear about your experiences with Azure, with Couchbase, and your overall impressions of cloud computing. Please leave a comment below, or talk to me on Twitter @mgroves.

This is a repost that originally appeared on the Couchbase Blog: Azure Functions with Couchbase Server.

Azure Functions are Microsoft’s answer to Amazon’s Lambdas or Google’s Cloud Functions (aka "serverless" architecture). They give you a way to deploy small pieces of code, and let Azure handle the underlying server. I’ve never used them before, so I thought I would give them a try beyond "Hello, World", by getting them to work with Couchbase Server.

There are more options in Azure Functions beyond simple HTTP events (e.g. Blob triggers, GitHub webhooks, Azure Storage queue triggers, etc). But, for this blog post, I’m going to focus on just HTTP events. I’ll create simple "Get" and "Set" endpoints that interact with Couchbase Server.

Before beginning, you can follow along by getting the source code for this blog post on GitHub.

Also, please read the Azure Functions and Lazy Initialization with Couchbase Server post. It contains an important update about using Couchbase Server and Azure Functions.

Getting setup to develop Azure Functions

For this blog post, I decided to try Visual Studio Preview.

Visual Studio Preview

I did this because there is a handy tool for creating Azure Function projects in Visual Studio.

Azure Functions tool for Visual Studio

But it only works for the preview version at this time. You don’t have to use these tools to develop Azure Functions, but it made the process simpler for me.

Once I had this tooling in place, all I had to was to File→New→Project. Then under "Cloud", select "Azure Functions".

New Azure Functions in Visual Studio

Once you do this, you’ll have an empty looking project with a couple of JSON files. Right click on the project, add item, and select "Azure Function".

Add Azure Function

Next, you’ll need to select what kind of Azure Function you want to create. I chose "HttpTrigger". I also chose "Anonymous" to keep this post simple, but depending on your use case, you may want to require an authentication token. After you do this, a very simple shell of a function will be generated (as a C# class). You can execute this function locally (indeed, that is what the local.settings.json file is for) so you can test it out without deploying to Azure yet.

Writing a "Get" function

First, I decided that I wanted two Azure Functions: one to "get" a piece of data by ID, and one to "set" a new piece of given data. I started by defining the shape of my data with a simple C# POCO:

public class MyDocument
{
    public string Name { get; set; }
    public int ShoeSize { get; set; }
    public decimal Balance { get; set; }
}

Here is the Azure function that I wrote to "get" that document from Couchbase Server:

public static async Task<HttpResponseMessage> Get([HttpTrigger(AuthorizationLevel.Anonymous, "get", Route = null)]HttpRequestMessage req, TraceWriter log)
{
    // parse query parameter
    var id = req.GetQueryNameValuePairs()
        .FirstOrDefault(q => string.Compare(q.Key, "id", true) == 0)
        .Value;

    using (var cluster = GetCluster())
    {
        using (var bucket = GetBucket(cluster))
        {
            var doc = await bucket.GetAsync<MyDocument>(id);
            return req.CreateResponse(HttpStatusCode.OK, doc.Value, new JsonMediaTypeFormatter());
        }
    }
}

Some things to note:

  • I remove the "post" that was generated by the tooling, since I want this to only be a "get" function.

  • Parsing the query parameter seems like a lot of extra code for this simple case. You can alternatively create a "function with parameters"

  • GetCluster and GetBucket will be discussed later in this post. But the short story is that I want this code to work both locally and deployed to Azure

Next, run this function locally, and you’ll get a console screen that looks similar to this:

Azure Functions running locally

At the bottom, you’ll notice that it tells you the Azure Function URL(s). Assuming I had a document in Couchbase (I don’t yet), I could create an HTTP request with a tool like Postman to: http://localhost:7071/api/HttpTriggerCsharpGet?id=123456

Currently, if I do that, I’ll get "null" as a response (since I don’t have any validation or error checking code). So let’s move on and create a "Set" function.

Writing a "Set" function

The "Set" function will be slightly different. I want document information POSTed to it, and I want it to return a message like "New document inserted with ID 123456".

public static async Task<HttpResponseMessage> Set([HttpTrigger(AuthorizationLevel.Anonymous, "post", Route = null)] MyDocument req, TraceWriter log)
{

    var id = Guid.NewGuid().ToString();

    using (var cluster = GetCluster())
    {
        using (var bucket = GetBucket(cluster))
        {
            await bucket.InsertAsync(id, req);
        }
    }

    return new HttpResponseMessage
    {
        Content = new StringContent($"New document inserted with ID {id}"),
        StatusCode = HttpStatusCode.OK
    };
}

This function has a similar shape to the Get, but some important things to note:

  • There is only "post" in the HttpTrigger attribute.

  • Instead of HttpRequestMessage as the first parameter, I’ve decided to use MyDocument, and let Azure Functions do the binding for me.

  • Since I don’t have HttpRequestMessage, I can’t call its CreateResponse method, so instead I instantiate a new HttpResponseMessage directly to return the success message at the end.

To create a request in Postman, I’ll use a URL of http://localhost:7071/api/HttpTriggerCsharpSet. In the headers, I’ll set Content-Type to "application/json". Finally, the body will be JSON:

{
    "Name": "matthew",
    "Balance": 107.18,
    "ShoeSize": 14
}

Now, when I POST that to the endpoint, I’ll get a response message of "New document inserted with ID f05ea97e-7c2f-4f88-b72d-19756f6a6f35".

Connecting to Couchbase Server

I have glossed over how these functions connect to Couchbase Server.

Previously, I mentioned two methods, GetCluster and GetBucket that will connect to the cluster and bucket, respectively.

private static Cluster GetCluster()
{
    var uri = ConfigurationManager.AppSettings["couchbaseUri"];
    return new Cluster(new ClientConfiguration
    {
        Servers = new List<Uri> { new Uri(uri) }
    });
}

private static IBucket GetBucket(Cluster cluster)
{
    var bucketName = ConfigurationManager.AppSettings["couchbaseBucketName"];
    var bucketPassword = ConfigurationManager.AppSettings["couchbaseBucketPassword"];

    return cluster.OpenBucket(bucketName, bucketPassword);
}

At this point, most of this code should be familiar if you’ve used Couchbase Server and the Couchbase .NET SDK before. I’m connecting to a single node cluster, and then connecting a bucket that has a password set (I’m using Couchbase Server 4.6).

But, the important thing to point out here is the use of Configuration.AppSettings. In the local.settings.json file, I’ve added these Couchbase settings to the Value section:

{
  "IsEncrypted": false,
  "Values": {
    "AzureWebJobsStorage": "",
    "AzureWebJobsDashboard": "",
    "couchbaseUri": "http://localhost:8091",
    "couchbaseBucketName": "azurefunctions",
    "couchbaseBucketPassword": "Password88!"
  }
}

When running Azure Functions locally, this file is used for configuration. I have Couchbase Server running locally with a bucket called "azurefunctions". Anything in "Values" can be accessed via Configuration.AppSettings.

Deploying to Azure

Before deploying the Azure Functions, I’ll need to create a Couchbase Cluster on Azure. This is very easy to do, thanks to Ben Lackey’s great work on the Azure Marketplace. Once that’s deployed, deploying the Azure Functions are also easy, thanks to Visual Studio.

Deploying Couchbase Server to Azure

Here is a short video walking you through the process of creating a Couchbase Server cluster on Azure.

For my example, I followed that video closely. Here is step 1, where I configure the username, password, and resource group.

Create Couchbase Cluster step 1

For the second step, I only created a single node cluster on the smallest, cheapest VM (DS1 v2). I created 0 Sync Gateway nodes, since I’m not using Sync Gateway for this example.

Create Couchbase Cluster step 1

Step 3 is just a summary, and step 4 is a confirmation. It will take 3-5 minutes for the Couchbase Cluster to start up in Azure.

Once the cluster is created, find the URL for the first node in the cluster (just as demonstrated in the above video). My URL looked something like: http://vm0.server-hsmkrefstzg2t.northcentralus.cloudapp.azure.com:8091. Go to this URL, login, and create a bucket (I called mine "azurefunctions", just like I did locally).

Deploying Azure Functions to Azure

Now, Couchbase Server is running. So let’s deploy the Azure Functions that will interact with it.

To begin, right-click the project in Visual Studio and select "publish". You’ll need to create a new publish profile the first time you do this, but that’s easy.

Publish Azure functions

Give your functions an app name, select a subscription, select a resource group (you can create a new one, or use the same group that you created above for Couchbase), select a service plan, and finally a storage account. You can create new ones when necessary.

Create Publish Profile

Click "create" and these items will start to be created in Azure (it may take a minute or two).

Trying out the Azure Functions

Finally, remember that the Azure Functions need to know the URI, bucket name, and password in order to connect to Couchbase Server. That information is in local.settings.json, but that file is not used for actual Azure deployments.

In the Azure portal, navigate to the Azure function (I called mine cbazurefunctions), and then select "Application Settings". Under "App settings", enter those three settings: couchbaseUri, couchbaseBucketName, and couchbaseBucketPassword.

Azure Functions App settings

Now, repeat the Postman process mentioned above to try out the Azure functions and make sure they work. Your URL will vary, but mine was http://cbazurefunctions.azurewebsites.net/.

Summary

This is my first time trying out Azure Functions. This blog post shows a simple demo, but there are other factors to consider before you start using this in production:

  • Authentication - I used anonymous Azure Functions to keep it simple. Azure Functions can also provide authentication tokens to use that prevent access except to authorized users.

  • App settings - Setting them manually in the portal may not be the best solution. There is probably a way to automate that portion, and that’s something I’ll look into in the future.

  • HTTPS/TLS - You will likely want to have some level of encryption as you are getting and posting data to your Azure Functions. The above example transmits everything in clear text.

Anything I missed? Any more tips or suggestions to share to make this process easier or better? Please leave a comment below or ping me on Twitter @mgroves.

Ron Groves talks about the technology shifts that have taken place in his software EZRep over the years.

Show Notes:

Want to be on the next episode? You can! All you need is the willingness to talk about something technical.

Theme music is "Crosscutting Concerns" by The Dirty Truckers, check out their music on Amazon or iTunes.

Matthew D. Groves

About the Author

Matthew D. Groves lives in Central Ohio. He works remotely, loves to code, and is a Microsoft MVP.

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