Added README, added extra _ between metrics prefix and name and chang…

…ed defaults

Dockerfile

@@ -6,6 +6,4 @@ RUN CGO_ENABLED=0 GOOS=linux GOARCH=amd64 GO11MODULE=on go build -mod=mod -a -o
 
 FROM alpine:latest
 COPY --from=builder /aws-subnet-exporter /aws-subnet-exporter
-COPY ./scripts/run.sh .
-RUN chmod +x run.sh
-CMD ["./run.sh"]
+CMD ["./aws-subnet-exporter"]

README.md

@@ -0,0 +1,43 @@
+# AWS subnet exporter
+Fetch AWS subnet available IP count and expose it as Prometheus metrics. Why? Because AWS does not expose these in CloudWatch and you don't want to run out of available IP's in your subnets.
+
+## Metrics exported
+```
+# Curl metrics example
+curl http://localhost:8080/metrics
+# HELP aws_subnet_exporter_available_ips Available IPs in subnets
+# TYPE aws_subnet_exporter_available_ips gauge
+aws_subnet_exporter_available_ips{az="eu-west-1a",cidrblock="10.103.0.0/28",name="eks_clu_eu-west-1a",subnetid="subnet-XXX",vpcid="vpc-YYY"} 10
+...
+
+# HELP aws_subnet_exporter_max_ips Max host IPs in subnet
+# TYPE aws_subnet_exporter_max_ips gauge
+aws_subnet_exporter_max_ips{az="eu-west-1a",cidrblock="10.103.0.0/28",name="eks_clu_eu-west-1a",subnetid="subnet-XXX",vpcid="vpc-YYY"} 14
+...
+```
+
+## Assumptions
+This service assumes that you subnets have a tag "Name" and that you have exported your AWS access key and secret.
+
+## AWS policy required
+You require this policy to your user/role (use roles for best practice) in order to fetch AWS subnet data.
+```json
+{
+    "Version": "2012-10-17",
+    "Statement": [
+        {
+            "Sid": "VisualEditor0",
+            "Effect": "Allow",
+            "Action": "ec2:DescribeSubnets",
+            "Resource": "*"
+        }
+    ]
+}
+```
+
+## Running
+You have to provide an AWS context and I will not cover how to do this here.
+
+```bash
+docker run -p 8080:8080 -e AWS_ACCESS_KEY_ID=xyz -e AWS_SECRET_ACCESS_KEY=aaa ghcr.io/wcarlsen/aws-subnet-exporter:latest ./aws-subnet-exporter --port="8080" --region="eu-west-1" --filter="*" --period="60" --debug
+```

cmd/aws-subnet-exporter/main.go

@@ -17,9 +17,9 @@ const (
 )
 
 var (
-	port   = flag.String("port", ":8080", "The port to listen on for HTTP requests.")
+	port   = flag.String("port", "8080", "The port to listen on for HTTP requests.")
 	region = flag.String("region", "eu-west-1", "AWS region")
-	filter = flag.String("filter", "*eks*", "Filter subnets by tag regex when calling AWS (assumes tag key is Name")
+	filter = flag.String("filter", "*", "Filter subnets by tag regex when calling AWS (assumes tag key is Name")
 	period = flag.Duration("period", 60*time.Second, "Period for calling AWS in seconds")
 	debug  = flag.Bool("debug", false, "Enable debug logging")
 )
@@ -63,5 +63,5 @@ func main() {
 
 	log.WithFields(log.Fields{"endpoint": endpoint, "port": port}).Info("Starting metrics web server")
 	http.Handle(endpoint, prom.Handler)
-	log.Fatal(http.ListenAndServe(*port, nil))
+	log.Fatal(http.ListenAndServe(":"+*port, nil))
 }

pkg/prometheus/metrics.go

@@ -5,7 +5,7 @@ import (
 )
 
 const (
-	prefix = "aws_subnet_exporter"
+	prefix = "aws_subnet_exporter_"
 )
 
 var (