Azure Functions npm install via VSTS

When setting upp build and release cycles for diffrent Azure resources we bump in to diffrent challenges, this post will cover the challenge of npm install of node modules in to a Function App when doing deployments.

When we are working with our development enviornment it’s okay to go in and run kudo commands and so on to make sure our Function App has the correct packages installed, but as we are adding speed and agility to our processes our Release pipelines in VSTS has to automate more of these processes. It’s not that it’s hard to go in to Kudo and run the command but it’s a manual step that takes time and knowledge when doing a release, I prefer to have everything prepped so that I know things are working when the Release is installed.

So let’s look in to how we can run Kudu commands from VSTS, since Kudu has a REST API we can use it for these kind of tasks, read more on it here Kudu Rest API

When looking in to the API documentation we easily find a function for executing commands:

POST /api/command
{
    "command": 'echo Hello World',
    "dir": 'site\\repository'
}

This means that we could create a message that looked like this for a npm install of the request package:

{
    "command": "npm install request",
    "dir": "site\\wwwroot"
}

So let’s start figuring out the rest, how to execute this from VSTS?

As good as it’s get this can be executed via PowerShell explained and sampled at the bottom of the API reference (I changed the sample in the following code snippet to execute the command for npm install):

$username = "`$website"
$password = "pwd"
# Note that the $username here should look like `SomeUserName`, and **not** `SomeSite\SomeUserName`
$base64AuthInfo = [Convert]::ToBase64String([Text.Encoding]::ASCII.GetBytes(("{0}:{1}" -f $username,$password)))

$userAgent = "powershell/1.0"
$apiUrl = "https://$functionAppName.scm.azurewebsites.net/api/command"
$command = '{"command": "npm install ' + $npmpackage + '","dir": "site\\wwwroot"}'

Invoke-RestMethod -Uri $apiUrl -Headers @{Authorization=("Basic {0}" -f $base64AuthInfo)} -UserAgent $userAgent -Method POST -Body $command -ContentType "application/json"

The credentials is now needed and that is somewhat messy, but since it’s the same as the deployment credentials we can add a commands to get that information via AzureRmResourceAction command:

$creds = Invoke-AzureRmResourceAction -ResourceGroupName $resourceGroup -ResourceType Microsoft.Web/sites/config `
            -ResourceName $functionAppName/publishingcredentials -Action list -ApiVersion 2015-08-01 -Force

So with this information we can now build a more generic script that will only need three (3) parameters to execute a npm install command on our Function App:

• functionAppName: the name of the Function App
• resourceGroupName: the name of the resource group that contains the Function App
• npmpackage: the npm package to install

param([string] $functionAppName, [string] $resourceGroup, [string] $npmpackage)

$creds = Invoke-AzureRmResourceAction -ResourceGroupName $resourceGroup -ResourceType Microsoft.Web/sites/config `
            -ResourceName $functionAppName/publishingcredentials -Action list -ApiVersion 2015-08-01 -Force

$username = $creds.Properties.PublishingUserName
$password = $creds.Properties.PublishingPassword


$base64AuthInfo = [Convert]::ToBase64String([Text.Encoding]::ASCII.GetBytes(("{0}:{1}" -f $username,$password)))

$userAgent = "powershell/1.0"
$apiUrl = "https://$functionAppName.scm.azurewebsites.net/api/command"
$command = '{"command": "npm install ' + $npmpackage + '","dir": "site\\wwwroot"}'

Invoke-RestMethod -Uri $apiUrl -Headers @{Authorization=("Basic {0}" -f $base64AuthInfo)} -UserAgent $userAgent -Method POST -Body $command -ContentType "application/json"

Now all we have left is to execute this script in a Azure Powershell Task that will install the npm pacakge during the release, image bellow shows the Release setup and as you can see the parameters are added in the “Script Arguments” input area. I’ve also added the zcript to a shared repo andlinked the build setup to be able to share the script and manage it in one place.

If you are using package.json files we can make sure all packages are installed via npm install command, let’s see how the following could look like with a package.json file:

Modifying the PowerShell script will then give us the following:

• functionAppName: the name of the Function App
• resourceGroupName: the name of the resource group that contains the Function App
• functionfolder: the name of the folder that the function is in (same name as the function)

param([string] $functionAppName, [string] $resourceGroup, [string] $functionfolder)

$creds = Invoke-AzureRmResourceAction -ResourceGroupName $resourceGroup -ResourceType Microsoft.Web/sites/config `
            -ResourceName $functionAppName/publishingcredentials -Action list -ApiVersion 2015-08-01 -Force

$username = $creds.Properties.PublishingUserName
$password = $creds.Properties.PublishingPassword

$base64AuthInfo = [Convert]::ToBase64String([Text.Encoding]::ASCII.GetBytes(("{0}:{1}" -f $username,$password)))

$userAgent = "powershell/1.0"
$apiUrl = "https://$functionAppName.scm.azurewebsites.net/api/command"
$command = '{"command": "npm install","dir": "site\\wwwroot\\'+ $functionfolder +'"}'

Invoke-RestMethod -Uri $apiUrl -Headers @{Authorization=("Basic {0}" -f $base64AuthInfo)} -UserAgent $userAgent -Method POST -Body $command -ContentType "application/json"

Summary:

I like to automate these tasks since it will give me a “easier” Release and a more reliable Release, but as for now it’s hard to verify that the package is installed and if it’s installed previously so a verification step that the function is loaded correctly is something that might be needed.

Recomended is to use the package.json approach since it shows the dependencies and allow to easyily add new packages, but jeep in mind that it also gives some delays when running the npm install command since it will install alot of packages the first time.

Posted in: •Azure Functions  | Tagged: | Azure Functions  | Integration  | Deployments