AB#2104 Feat/azure logging (#198)

implementation for azure early boot logging

internal/azureshared/metadata.go

@@ -0,0 +1,61 @@
+package azureshared
+
+import (
+	"errors"
+	"fmt"
+	"regexp"
+	"strings"
+)
+
+var (
+	azureVMProviderIDRegexp   = regexp.MustCompile(`^azure:///subscriptions/([^/]+)/resourceGroups/([^/]+)/providers/Microsoft.Compute/virtualMachines/([^/]+)$`)
+	azureVMSSProviderIDRegexp = regexp.MustCompile(`^azure:///subscriptions/([^/]+)/resourceGroups/([^/]+)/providers/Microsoft.Compute/virtualMachineScaleSets/([^/]+)/virtualMachines/([^/]+)$`)
+)
+
+// BasicsFromProviderID extracts subscriptionID and resourceGroup from both types of valid azure providerID.
+func BasicsFromProviderID(providerID string) (subscriptionID, resourceGroup string, err error) {
+	subscriptionID, resourceGroup, _, err = VMInformationFromProviderID(providerID)
+	if err == nil {
+		return subscriptionID, resourceGroup, nil
+	}
+	subscriptionID, resourceGroup, _, _, err = ScaleSetInformationFromProviderID(providerID)
+	if err == nil {
+		return subscriptionID, resourceGroup, nil
+	}
+	return "", "", fmt.Errorf("providerID %v is malformatted", providerID)
+}
+
+// UIDFromProviderID extracts our own generated unique ID, which is the
+// suffix at the resource group, e.g., resource-group-J18dB
+// J18dB is the UID.
+func UIDFromProviderID(providerID string) (string, error) {
+	_, resourceGroup, err := BasicsFromProviderID(providerID)
+	if err != nil {
+		return "", err
+	}
+
+	parts := strings.Split(resourceGroup, "-")
+	return parts[len(parts)-1], nil
+}
+
+// VMInformationFromProviderID splits a provider's id belonging to a single azure instance into core components.
+// A providerID  for individual VMs is build after the following schema:
+// - 'azure:///subscriptions/<subscription-id>/resourceGroups/<resource-group>/providers/Microsoft.Compute/virtualMachines/<instance-name>'
+func VMInformationFromProviderID(providerID string) (subscriptionID, resourceGroup, instanceName string, err error) {
+	matches := azureVMProviderIDRegexp.FindStringSubmatch(providerID)
+	if len(matches) != 4 {
+		return "", "", "", errors.New("error splitting providerID")
+	}
+	return matches[1], matches[2], matches[3], nil
+}
+
+// ScaleSetInformationFromProviderID splits a provider's id belonging to an azure scaleset into core components.
+// A providerID for scale set VMs is build after the following schema:
+// - 'azure:///subscriptions/<subscription-id>/resourceGroups/<resource-group>/providers/Microsoft.Compute/virtualMachineScaleSets/<scale-set-name>/virtualMachines/<instance-id>'
+func ScaleSetInformationFromProviderID(providerID string) (subscriptionID, resourceGroup, scaleSet, instanceID string, err error) {
+	matches := azureVMSSProviderIDRegexp.FindStringSubmatch(providerID)
+	if len(matches) != 5 {
+		return "", "", "", "", errors.New("error splitting providerID")
+	}
+	return matches[1], matches[2], matches[3], matches[4], nil
+}