isabella232 / azure-durable-functions-hello-world

Running Cumulus core functions test on Azure as preliminary research vis a vis cloud agnosticism

Azure Durable Functions hello world

Testing Azure Durable Functions as a replacement for AWS step functions in building a cloud-agnostic Cumulus.

Prerequisites

Working with Azure Functions and newer bindings such as the Durable Function extension can be difficult if you're not using a Microsoft IDE. Furthermore, some core dependencies present gotcha's relating to version mismanagement. These pre-requisites are necessary to deploy and develop on these functions.

1. Azure CLI (instructions for Ubuntu).
2. Azure functions core tools, which I recommend using the global npm installation method.
3. .NET 2.2 SDK.

Running these functions locally

1. Install node dependencies (in the app directory): cd app && yarn install.

2. Install Azure function v2 bindings. The Azure functions core tools library will scan your functions and install the necessary bindings. However, at time of writing it includes a legacy version of the durable functions binding, which must be overridden.

cd app
# Install default bindings
func extensions install
# Override durable functions version
func extensions install --package Microsoft.Azure.WebJobs.Extensions.DurableTask --version 1.7.1

3. cd app && func host start

Deploying these functions to Azure

Make sure you have access to an Azure account with a working subscription, ie pay-as-you-go, otherwise the CLI will not allow you to partition resources.

Deployment steps

1. Log into the CLI: az login. This opens a login dialogue in a web browser.

2. Create a resource group:

az group create --name dsDurableFunctionsTest --location "West US"

3. Create a storage account:

az storage account create --name <STORAGE_ACCOUNT_NAME> --location "West US" --resource-group dsDurableFunctionsTest --sku Standard_LRS

Note, storage account names weirdly 1. can only contain lower-case alphanumeric characters and 2. must be unique.

4. Create a function resource:

az functionapp create --resource-group dsDurableFunctionsTest --consumption-plan-location westus --name dsDurableFunctions --storage-account <STORAGE_ACCOUNT_NAME> --runtime node

5. Install node dependencies (in the app directory): cd app && yarn install.

6. Install Azure function v2 bindings. The Azure functions core tools library will scan your functions and install the necessary bindings. However, at time of writing it includes a legacy version of the durable functions binding, which must be overridden.

cd app
# Install default bindings
func extensions install
# Override durable functions version
func extensions install --package Microsoft.Azure.WebJobs.Extensions.DurableTask --version 1.7.1

7. Create a zip of the app directory:

rm app.zip
cd app
zip -r ../app.zip ./*

8. Deploy the zip file:

az functionapp deployment source config-zip -g dsDurableFunctionsTest -n dsDurableFunctions --src app.zip

9. Test the basic function at https://dsdurablefunctions.azurewebsites.net/api/reply.

10. Test the orchestrator function at https://dsdurablefunctions.azurewebsites.net/api/orchestrators/orchestrator.