Configure a Linux application workload

  • 45 minutes

In this unit, you will:

  • Configure a Linux application workload to connect to Azure Database for PostgreSQL by using a system-assigned managed identity.
  • Connect to the Azure virtual machine by using the Azure CLI.
  • Install the necessary tools.
  • Connect to the PostgreSQL server by using psql.
  • Clone the repository that contains the sample application.
  • Run the application and confirm that it can connect to the PostgreSQL server by using the managed identity.

Get the currently logged-in user and the VM ID

USER_ID=$(az ad signed-in-user show --query id --output tsv)
VM_ID=$(az vm show --resource-group 240900-linux-postgres --name vm-1 --query id --output tsv)

Assign the Virtual Machine Administrator Login role to the user for the VM

You can read more about privileged roles for Azure VMs in Azure built-in roles for Privileged.

az role assignment create \
    --assignee $USER_ID \
    --scope $VM_ID \
    --role "Virtual Machine Administrator Login"

Connect to the Azure virtual machine by using the Azure CLI

az ssh vm --resource-group 240900-linux-postgres --name vm-1

Install psql and Go on the virtual machine

Update the package list:

sudo apt-get update

Install the PostgreSQL client and Go (Golang) on the virtual machine:

sudo apt-get install -y postgresql-client golang-go

Confirm the version of psql

psql --version

Install the Azure CLI on the virtual machine

curl -sL https://aka.ms/InstallAzureCLIDeb | sudo bash

Sign in to the Azure CLI by using the system-assigned managed identity

az login --identity

The following output appears:

$ az login --identity
[
  {
    "environmentName": "AzureCloud",
    "homeTenantId": "b4c72be8-cae1-4584-be77-62b1e94ad0dc",
    "id": "57039e18-c12e-4c87-a3e8-bf497991699d",
    "isDefault": true,
    "managedByTenants": [],
    "name": "CloudNative",
    "state": "Enabled",
    "tenantId": "b4c72be8-cae1-4584-be77-62b1e94ad0dc",
    "user": {
      "assignedIdentityInfo": "MSI",
      "name": "systemAssignedIdentity",
      "type": "servicePrincipal"
    }
  }
]

Connect to the PostgreSQL server by using Bash and psql

Run the following commands on the remote machine:

MANAGED_IDENTITY_NAME=240900-linux-postgres-identity
export AZURE_CLIENT_ID=$(az identity show --resource-group 240900-linux-postgres --name $MANAGED_IDENTITY_NAME --query "clientId" -o tsv)
PG_NAME=$(az postgres flexible-server list --resource-group 240900-linux-postgres --query "[0].name" -o tsv)

# Set psql environment variables
export PGHOST="${PG_NAME}.privatelink.postgres.database.azure.com"
export PGPASSWORD=$(curl -s "http://169.254.169.254/metadata/identity/oauth2/token?api-version=2018-02-01&resource=https%3A%2F%2Fossrdbms-aad.database.windows.net&client_id=${AZURE_CLIENT_ID}" -H Metadata:true | jq -r .access_token)
export PGUSER=$MANAGED_IDENTITY_NAME
export PGDATABASE=postgres

# Log in by using psql
psql

After you're connected, the following output appears. Enter the \q command to exit.

$ psql
psql (16.4 (Ubuntu 16.4-0ubuntu0.24.04.2))
SSL connection (protocol: TLSv1.3, cipher: TLS_AES_256_GCM_SHA384, compression: off)
Type "help" for help.

postgres=> \q
$

Clone the sample application

Clone the sample application, Tailwind Traders (Go). Run the following commands on the remote machine:

git clone https://github.com/Azure-Samples/tailwind-traders-go.git

Change to the application directory:

cd tailwind-traders-go/app/

Run the application:

go run main.go

The output should be similar to:

$ go run main.go
go: downloading github.com/magefile/mage v1.15.0
go: downloading github.com/Azure/azure-sdk-for-go/sdk/azcore v1.14.0
go: downloading github.com/Azure/azure-sdk-for-go/sdk/azidentity v1.7.0
go: downloading github.com/Azure/azure-sdk-for-go/sdk/internal v1.10.0
go: downloading github.com/AzureAD/microsoft-authentication-library-for-go v1.2.2
go: downloading golang.org/x/crypto v0.26.0
go: downloading golang.org/x/net v0.28.0
go: downloading github.com/google/uuid v1.6.0
go: downloading github.com/pkg/browser v0.0.0-20240102092130-5ac0b6a4141c
go: downloading github.com/kylelemons/godebug v1.1.0
go: downloading github.com/golang-jwt/jwt/v5 v5.2.1
go: downloading golang.org/x/text v0.17.0
Targets:
  app:connectionString    outputs a connection string for the database from env vars
  app:ping                pings the database
  app:serve               runs a web server for our application
  app:tables              lists the tables in the database
  app:token               gets a token using `azidentity.NewDefaultAzureCredential`

Connect to the PostgreSQL server by using the Tailwind Traders (Go) app:token target

MANAGED_IDENTITY_NAME=240900-linux-postgres-identity
export AZURE_CLIENT_ID=$(az identity show --resource-group 240900-linux-postgres --name $MANAGED_IDENTITY_NAME --query "clientId" -o tsv)
PG_NAME=$(az postgres flexible-server list --resource-group 240900-linux-postgres --query "[0].name" -o tsv)

# psql
export PGHOST="${PG_NAME}.privatelink.postgres.database.azure.com"
export PGPASSWORD=$(go run main.go app:token)
export PGUSER=$MANAGED_IDENTITY_NAME
export PGDATABASE=postgres

# Log in by using psql
psql

Quit psql and disconnect from the remote machine

Quit psql:

\q

Disconnect from the remote machine:

exit

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