Managing Sensitive Information in a GitHub Workflow
Welcome to Part 2 of this 2-Part series where we explore different ways for managing sensitive information in GitHub workflows. In this part we look at how we can use Azure Key Vault as a secure Secrets store and how to integrate your GitHub Workflows with Key Vault for retrieving Secrets, to enhanced security and for more flexible centralised management of your GitHub Secrets.
I recommend reading Part 1 of the series where we explore the best practices for managing sensitive information in GitHub workflows using GitHub Secrets natively in the GitHub Website UI and giving a general overview and feel for GitHub Secrets and why you would want to make use of them.
Let's jump straight in and see how we can integrate Azure Key Vault with GitHub.
Integrating Azure Key Vault with GitHub Workflows
Azure Key Vault is a cloud service for securely storing and accessing secrets. Integrating it with GitHub Action Workflows provides an extra layer of security and more flexibility for managing your secrets.
One of the biggest benefits of using Azure Key Vault is that it allows you to store your secrets in a centralised location, separate from your codebase, apart from Organization Secrets, it addresses the limitation with Repository Secrets where secrets have to be set in each unique repository which can make secrets management or rotation cumbersome.
To name a few more benefits of using Secrets in GitHub with Azure Key Vault is that they can be accessed by multiple repositories and workflows, secret rotation can be managed centrally, access to secrets can be controlled using Azure RBAC, secrets history can also be maintained for auditing purposes and previous versions of secrets can be restored if needed.
There are a few things we need first to integrate Azure Key Vault with GitHub Workflows:
Prerequisites
- GitHub repository.
- Azure Subscription.
- Azure Key Vault.
- Azure Service Principal with access to the Key Vault.
Step-by-Step Integration Example
At the time of writing and for the purposes of the example to follow the following tools were used to prepare the prerequisites for the integration:
- Windows operating system.
- GitHub CLI v2.52.0 to create a GitHub repository.
- Azure CLI v2.62.0 to create an Azure Key Vault, Secrets and supporting resources.
In the following example we will integrate an Azure Key Vault with a GitHub Actions workflow, by integrating Azure with a GitHub Repository using a federated/passwordless service principal (identity) to access an Azure Storage Account as part of the workflow execution and using the Storage Account Key stored as a secret in the Key Vault to create a Storage Container and copy a Blob file into the created container.
1. Set Up Azure Key Vault:
Once you have a suitable Azure Subscription, we will create a Resource Group, Key Vault, Storage Account and then store the Storage Account Key inside of the Key Vault as a secret, which we will later retrieve and use in our GitHub Actions workflow:
# Create Resource Group, Key Vault, Storage Account and set "StorageAccountKey" as secret in Key Vault
# Set variables
$randomInt = Get-Random -Maximum 9999
$subscriptionId = $(az account show --query "id" --output tsv)
$resourceGroupName = "ghSecretsRg"
$location = "UKSouth"
$keyVaultName = "ghSecretsVault$randomInt"
$storageAccountName = "ghsecsa$randomInt"
$currentUser = $(az ad signed-in-user show --query "id" --output tsv)
# Create Resource Group
az group create --name "$resourceGroupName" --location "$location"
# Create Key Vault
az keyvault create --name "$keyVaultName" --resource-group "$resourceGroupName" --location "$location"
# Set RBAC access to the operation for maintaining secrets - grant signed in user access
az role assignment create --assignee-object-id "$currentUser" `
--role "Key Vault Secrets Officer" `
--scope "/subscriptions/$subscriptionId/resourceGroups/$resourceGroupName/providers/Microsoft.KeyVault/vaults/$keyVaultName" `
--assignee-principal-type "User"
# Create storage account
az storage account create --name "$storageAccountName" --resource-group "$resourceGroupName" --location "$location" --sku Standard_LRS
# Fetch and store a Storage Account Key in Key Vault
$storageKey = az storage account keys list --account-name "$storageAccountName" --resource-group "$resourceGroupName" --query "[0].value" --output tsv
az keyvault secret set --vault-name "$keyVaultName" --name "StorageAccountKey" --value "$storageKey"
In the Resource Group created by the above script you will see a Storage Account and Key Vault. Notice that the Storage Account Key has been stored as a secret in the Key Vault called StorageAccountKey:
2. Create a GitHub Repository (Optional):
For the purposes of this example we will use the GitHub CLI to create a new repository and initialise it with a README.md file, but you can also skip this step if you already have a repository you would like to integrate with Azure Key Vault:
# Authenticate to GitHub
gh auth login
# Create a new repository
gh repo create "Integration-Test-Repo" --public --description "Azure Key Vault Integrated Test Repository"
# Clone the new repository (Replace <your-username> with your actual GitHub username.)
git clone "https://github.com/<your-username>/Integration-Test-Repo.git"
cd "Integration-Test-Repo"
# Create a new file and add content
echo "# Key Vault Integration Test Repo" > README.md
# Add the file to the staging area
git add README.md
# Commit the file
git commit -m "Initial commit"
# Push the changes to GitHub (If you are not using the main branch, replace 'main' with your branch name. e.g. 'master')
git push origin main
As you can see we have created a new GitHub repository called Integration-Test-Repo and initialised it with a README.md file.
Now that we have our GitHub repository set up, we can move on to the next step to integrate it with our Azure Key Vault.
3. Configure Azure Service Principal:
Next we will create a federated service principal (passwordless) in Azure Entra ID and grant it access to the Key Vault. We will integrate this service principal (identity) to access the Key Vault from our GitHub Actions workflow later on:
# Set variables
$subscriptionId = $(az account show --query id -o tsv)
$resourceGroupName = "ghSecretsRg" # Resource Group Name where Key Vault is located
$keyVaultName = "ghSecretsVault4089" # Key Vault Name to access
$appName = "GitHub-projectName-Actions-OIDC" # App Registration Name
$RBACRole = "Key Vault Secrets User" # RBAC Role to apply
$githubOrgName = "Pwd9000-ML" # GitHub Organization/User Name
$githubRepoName = "Integration-Test-Repo" # GitHub Repository Name
$githubBranch = "master" # GitHub Branch Name
# Create AAD App and Principal
$appId = $(az ad app create --display-name $appName --query appId -o tsv)
az ad sp create --id $appId
# Create federated GitHub credentials (Entity type 'Branch')
$githubBranchConfig = [PSCustomObject]@{
name = "GH-[$githubOrgName-$githubRepoName]-Branch-[$githubBranch]"
issuer = "https://token.actions.githubusercontent.com"
subject = "repo:" + "$githubOrgName/$githubRepoName" + ":ref:refs/heads/$githubBranch"
description = "Federated credential linked to GitHub [$githubBranch] branch @: [$githubOrgName/$githubRepoName]"
audiences = @("api://AzureADTokenExchange")
}
$githubBranchConfigJson = $githubBranchConfig | ConvertTo-Json
$githubBranchConfigJson | az ad app federated-credential create --id $appId --parameters "@-"
# Create federated GitHub credentials (Entity type 'Pull Request')
$githubPRConfig = [PSCustomObject]@{
name = "GH-[$githubOrgName-$githubRepoName]-PR"
issuer = "https://token.actions.githubusercontent.com"
subject = "repo:" + "$githubOrgName/$githubRepoName" + ":pull_request"
description = "Federated credential linked to GitHub Pull Requests @: [$githubOrgName/$githubRepoName]"
audiences = @("api://AzureADTokenExchange")
}
$githubPRConfigJson = $githubPRConfig | ConvertTo-Json
$githubPRConfigJson | az ad app federated-credential create --id $appId --parameters "@-"
### Additional federated GitHub credential entity types are 'Tag' and 'Environment' (see: https://docs.microsoft.com/en-us/azure/active-directory/develop/workload-identity-federation-create-trust?pivots=identity-wif-apps-methods-azcli#github-actions-example?wt.mc_id=DT-MVP-5004771) ###
# Assign RBAC permissions on Service Principal to access KeyVault (Change as necessary)
$appId | foreach-object {
# Permission 1 (Example)
az role assignment create `
--role $RBACRole `
--assignee $_ `
--scope "/subscriptions/$subscriptionId/resourceGroups/$resourceGroupName/providers/Microsoft.KeyVault/vaults/$keyVaultName"
# Permission 2 (Example)
#az role assignment create `
# --role "Reader and Data Access" `
# --assignee "$_" `
# --scope "/subscriptions/$subscriptionId/resourceGroups/$resourceGroupName/providers/Microsoft.Storage/storageAccounts/$storageName"
}
As you can see we have created a service principal in Azure Entra ID called GitHub-projectName-Actions-OIDC.
Note that the service principal is federated with GitHub credentials for my created repository on Branch and Pull Request entity types.
Also note that the service principal has been granted access to the Key Vault with the Key Vault Secrets User role.
The last step to integrate the Service Principal with our GitHub Repository we will need to add the Application ID of the Service Principal as well as our Azure Tenant ID and Azure Subscription ID as GitHub Secrets into our repository. Since the Service Principal is federated/passwordless with GitHub credentials, we do not have to add any Client Secret.
Navigate to your GitHub Repository and go to the Settings tab, then click on Secrets and variables and add the following GitHub Secrets:
- AZURE_CLIENT_ID: The Application ID of the federated Service Principal.
- AZURE_TENANT_ID: The Azure Tenant ID of your Azure Subscription.
- AZURE_SUBSCRIPTION_ID: The Azure Subscription ID of your Azure Subscription.
NOTE: You can also check this previous blog post I wrote for more information about federated access between Azure and GitHub and other mechanisms and ways for integration between Azure and GitHub: GitHub Actions authentication methods for Azure
4. Access Azure Key Vault in GitHub Actions:
That is it for the setup and configuration of the Azure Key Vault and the Service Principal. Now we can utilise the federated Service Principal to access the Key Vault from our GitHub Actions Workflow.
Let's test this by creating a simple GitHub Actions workflow file in our repository to access the Key Vault secret we created earlier called StorageAccountKey. We will retrieve the Storage Account Key from the Key Vault and use it in our workflow to create a new storage container and copy a file into the storage container:
name: Azure Key Vault Integration Test
on: [push]
permissions:
id-token: write
contents: read
jobs:
access-key-vault:
runs-on: ubuntu-latest
steps:
- name: Checkout code
uses: actions/checkout@v4
- name: Log in to Azure using federated Service Principal
uses: azure/login@v2
with:
client-id: ${{ secrets.AZURE_CLIENT_ID }}
tenant-id: ${{ secrets.AZURE_TENANT_ID }}
subscription-id: ${{ secrets.AZURE_SUBSCRIPTION_ID }}
- name: Retrieve secret from Key Vault
id: get-secret-sa-key
uses: azure/cli@v2
with:
azcliversion: latest
inlineScript: |
# Variables
KEY_VAULT_NAME=ghSecretsVault4089
SECRET_NAME=StorageAccountKey
# Retrieve secret from Key Vault
STORAGE_KEY=$(az keyvault secret show --name $SECRET_NAME --vault-name $KEY_VAULT_NAME --query value -o tsv)
# Create a container in Azure Storage Account using the secret
az storage container create --name "ghrepocontainer" --account-name "ghsecsa4089" --account-key "$STORAGE_KEY"
# Copy a text file saying "Hello World" to the container
echo "Hello World" > hello.txt
az storage blob upload --container-name "ghrepocontainer" --file hello.txt --name hello.txt --account-name "ghsecsa4089" --account-key "$STORAGE_KEY"
# You can also set the retrieved secret as an output for use in subsequent steps in the workflow
echo "::set-output name=secret_value::$STORAGE_KEY"
- name: Use the retrieved secret in another step (example)
uses: azure/cli@v2
with:
azcliversion: latest
inlineScript: |
# Use the secret output from the previous step
# WARNING! Output secret to workflow log just as an example for the purposes of this demonstration
echo "The secret value is: ${{ steps.get-secret-sa-key.outputs.secret_value }}"
Note that after running the workflow above:
The Storage Account Key was retrieved from the Key Vault and used to create a new storage container called ghrepocontainer:
We also used the same retrieved Storage Account Key to upload a file called hello.txt to the storage container:
This retrieval and usage of the Storage Account Key from the Key Vault was done using an inline script with the azure/cli@v2 action in the workflow file in the following step:
- name: Retrieve secret from Key Vault
id: get-secret-sa-key
uses: azure/cli@v2
with:
azcliversion: latest
inlineScript: |
# Variables
KEY_VAULT_NAME=ghSecretsVault4089
SECRET_NAME=StorageAccountKey
# Retrieve secret from Key Vault
STORAGE_KEY=$(az keyvault secret show --name $SECRET_NAME --vault-name $KEY_VAULT_NAME --query value -o tsv)
# Create a container in Azure Storage Account using the secret
az storage container create --name "ghrepocontainer" --account-name "ghsecsa4089" --account-key "$STORAGE_KEY"
# Copy a text file saying "Hello World" to the container
echo "Hello World" > hello.txt
az storage blob upload --container-name "ghrepocontainer" --file hello.txt --name hello.txt --account-name "ghsecsa4089" --account-key "$STORAGE_KEY"
# You can also set the retrieved secret as an output for use in subsequent steps in the workflow
echo "::set-output name=secret_value::$STORAGE_KEY"
NOTE: As you can see from the step above we can also optionally set the retrieved secret as an output as part of the workflow execution, for use in any other subsequent steps in the workflow using this syntax: echo "::set-output name=secret_value::$STORAGE_KEY". We can then use the output secret in another step in the workflow using this syntax: ${{ steps.get-secret-sa-key.outputs.secret_value }} as you can see in the next step of our workflow:
- name: Use the retrieved secret in another step (example)
uses: azure/cli@v2
with:
azcliversion: latest
inlineScript: |
# Use the secret output from the previous step
# WARNING! Output secret to workflow log just as an example for the purposes of this demonstration
echo "The secret value is: ${{ steps.get-secret-sa-key.outputs.secret_value }}"
Conclusion
Managing sensitive information securely is vital for any DevOps workflow. By integrating Azure Key Vault for Secrets management in GitHub, you can ensure that your secrets are stored and accessed securely and managed centrally providing more flexibility for managing your secrets.
Always follow best practices and avoid common pitfalls to maintain the security and integrity of your applications.
I hope you have enjoyed this post and have learned something new. ❤️
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