Add stub blob collector for azure

Author: suntala

docs/README.md

@@ -11,6 +11,6 @@
   - [Providers](metrics/providers.md)
   - **AWS:** [EC2](metrics/aws/ec2.md), [S3](metrics/aws/s3.md), [RDS](metrics/aws/rds.md), [ELB](metrics/aws/elb.md), [NAT Gateway](metrics/aws/natgateway.md), [VPC](metrics/aws/vpc.md)
   - **GCP:** [GKE](metrics/gcp/gke.md), [GCS](metrics/gcp/gcs.md), [Cloud SQL](metrics/gcp/cloudsql.md), [CLB](metrics/gcp/clb.md), [VPC](metrics/gcp/vpc.md)
-  - **Azure:** [AKS](metrics/azure/aks.md)
+  - **Azure:** [AKS](metrics/azure/aks.md), [Blob](metrics/azure/blob.md)
 - [Deploying](deploying/aws/README.md) - Run the exporter
   - [AWS](deploying/aws/README.md) — IRSA, Helm, cross-account access

docs/metrics/README.md

@@ -20,3 +20,4 @@
 ## Azure Services
 
 - **[AKS](./azure/aks.md)** - Azure Kubernetes Service VM instances and managed disks
+- **[Blob](./azure/blob.md)** - Azure Blob Storage (stub; Cost Management integration planned)

docs/metrics/azure/blob.md

@@ -0,0 +1,26 @@
+# Azure Blob Storage metrics
+
+## Status
+
+The `BLOB` service is registered when you pass `BLOB` in `--azure.services`. The collector is a **stub**: it does not call Azure APIs for cost data yet and emits **no** `cloudcost_azure_blob_*` cost gauges.
+
+## Planned behavior (see issue #54):
+
+### Metric shape (AWS S3 and GCP GCS in this repo)
+
+- **Storage rate:** Same naming pattern as S3 and GCS: `storage_by_location_usd_per_gibyte_hour` under the service subsystem (here `azure_blob` → `cloudcost_azure_blob_storage_by_location_usd_per_gibyte_hour`). Implemented today as `cloudcost_aws_s3_*` in `pkg/aws/s3/s3.go` and `cloudcost_gcp_gcs_*` in `pkg/google/metrics/metrics.go`.
+- **Operations rate (optional):** S3 and GCS also define `operation_by_location_usd_per_krequest` (`pkg/aws/s3/s3.go`, `pkg/google/metrics/metrics.go`). A Blob collector may expose an analogous gauge only if the chosen Azure dataset supports it.
+- **Labels:** S3 uses `region` and `class` for storage (and `tier` for operations); GCS uses `location` and `storage_class` (and operation class labels for ops). Azure label sets would follow whatever dimensions the Cost Management query returns; the above collectors show the cross-cloud “by location + storage class/tier” pattern only.
+
+### Azure Cost Management
+
+- **Query API:** Azure documentation mentions `POST https://management.azure.com/{scope}/providers/Microsoft.CostManagement/query` and states that `{scope}` includes **`/subscriptions/{subscriptionId}/`** for subscription scope. Sample responses in that snapshot include cost columns such as **`PreTaxCost`** alongside dimensions like **`ResourceLocation`** in example filters.
+- **Permissions:** Azure documentation states that you must have **Cost Management permissions at the appropriate scope** to use Cost Management APIs (the captured article links to Microsoft’s assign-access documentation for details). No specific Azure role name is asserted here.
+
+### Provider operational metrics
+
+- **`cloudcost_exporter_collector_*` with `collector="azure_blob"`** — same mechanism as other Azure collectors (e.g. `azure_aks`) via `pkg/azure/azure.go` and the shared gatherer pattern.
+
+## Cost metrics
+
+None yet.

pkg/azure/azure.go

@@ -12,6 +12,7 @@ import (
 	"github.com/prometheus/client_golang/prometheus"
 
 	"github.com/grafana/cloudcost-exporter/pkg/azure/aks"
+	"github.com/grafana/cloudcost-exporter/pkg/azure/blob"
 	"github.com/grafana/cloudcost-exporter/pkg/azure/client"
 	"github.com/grafana/cloudcost-exporter/pkg/collectormetrics"
 	"github.com/grafana/cloudcost-exporter/pkg/provider"
@@ -101,6 +102,14 @@ func New(ctx context.Context, config *Config) (*Azure, error) {
 				return nil, err
 			}
 			collectors = append(collectors, collector)
+		case "BLOB":
+			collector, err := blob.New(&blob.Config{
+				Logger: logger,
+			})
+			if err != nil {
+				return nil, err
+			}
+			collectors = append(collectors, collector)
 		default:
 			logger.LogAttrs(ctx, slog.LevelInfo, "unknown service", slog.String("service", svc))
 		}

pkg/azure/blob/blob.go

@@ -0,0 +1,51 @@
+package blob
+
+import (
+	"context"
+	"log/slog"
+
+	"github.com/grafana/cloudcost-exporter/pkg/provider"
+	"github.com/prometheus/client_golang/prometheus"
+)
+
+const subsystem = "azure_blob"
+
+// Collector implements provider.Collector for Azure Blob Storage cost metrics.
+// Cost Management integration is not implemented yet; Collect emits no cost series.
+type Collector struct {
+	logger *slog.Logger
+}
+
+// Config holds settings for the blob collector.
+type Config struct {
+	Logger *slog.Logger
+}
+
+// New builds a blob collector. It does not call Azure APIs.
+func New(cfg *Config) (*Collector, error) {
+	return &Collector{
+		logger: cfg.Logger.With("collector", "blob"),
+	}, nil
+}
+
+// Collect satisfies provider.Collector. No Prometheus samples are sent until Cost Management is wired in.
+func (c *Collector) Collect(ctx context.Context, _ chan<- prometheus.Metric) error {
+	c.logger.LogAttrs(ctx, slog.LevelInfo, "collecting metrics")
+	return nil
+}
+
+// Describe satisfies provider.Collector. No metric descriptors until cost gauges are implemented.
+func (c *Collector) Describe(_ chan<- *prometheus.Desc) error {
+	return nil
+}
+
+// Name returns the collector subsystem name for operational metrics.
+func (c *Collector) Name() string {
+	return subsystem
+}
+
+// Register satisfies provider.Collector.
+func (c *Collector) Register(_ provider.Registry) error {
+	c.logger.LogAttrs(context.Background(), slog.LevelInfo, "registering collector")
+	return nil
+}