Monitoring HTTP using Blackbox exporter
Blackbox exporter can monitor the external services over HTTP, HTTPS, DNS, TCP, ICMP on Prometheus. In this post, I’ll show you how to monitor HTTP/HTTPS using Blackbox exporter. Blackbox exporter is going to be running on Kubernetes.
Environment
Before you begin, you need to have these:
- Kubernetes
- Prometheus operator
Blackbox exporter configuration
Write the Blackbox configuration file as ConfigMap to configure http module for monitoring web services.
apiVersion: v1
kind: ConfigMap
metadata:
name: prometheus-blackbox-exporter
labels:
app: prometheus-blackbox-exporter
data:
blackbox.yaml: |
modules:
http_2xx:
http:
no_follow_redirects: false
preferred_ip_protocol: ip4
valid_http_versions:
- HTTP/1.1
- HTTP/2
valid_status_codes: []
prober: http
timeout: 5s
The http_2xx module is used to check if the web service returns 2xx HTTP status code through the HTTP protocol. Learn more about the Blackbox exporter configuration in this doc.
Deploy Blackbox exporter to Kubernetes cluster
Write the Deployment and Service to be deployed to Kubernetes.
---
kind: Service
apiVersion: v1
metadata:
name: prometheus-blackbox-exporter
labels:
app: prometheus-blackbox-exporter
spec:
type: ClusterIP
ports:
- name: http
port: 9115
protocol: TCP
selector:
app: prometheus-blackbox-exporter
---
apiVersion: apps/v1
kind: Deployment
metadata:
name: prometheus-blackbox-exporter
labels:
app: prometheus-blackbox-exporter
spec:
replicas: 1
selector:
matchLabels:
app: prometheus-blackbox-exporter
template:
metadata:
labels:
app: prometheus-blackbox-exporter
spec:
restartPolicy: Always
containers:
- name: blackbox-exporter
image: "prom/blackbox-exporter:v0.15.1"
imagePullPolicy: IfNotPresent
securityContext:
readOnlyRootFilesystem: true
runAsNonRoot: true
runAsUser: 1000
args:
- "--config.file=/config/blackbox.yaml"
resources:
{}
ports:
- containerPort: 9115
name: http
livenessProbe:
httpGet:
path: /health
port: http
readinessProbe:
httpGet:
path: /health
port: http
volumeMounts:
- mountPath: /config
name: config
- name: configmap-reload
image: "jimmidyson/configmap-reload:v0.2.2"
imagePullPolicy: "IfNotPresent"
securityContext:
runAsNonRoot: true
runAsUser: 65534
args:
- --volume-dir=/etc/config
- --webhook-url=http://localhost:9115/-/reload
resources:
{}
volumeMounts:
- mountPath: /etc/config
name: config
readOnly: true
volumes:
- name: config
configMap:
name: prometheus-blackbox-exporter
Blackbox exporter can be deployed by the following command. monitoring namespace is specified for Prometheus operator.
kubectl --namespace=monitoring apply -f blackbox-exporter.yaml
Verify that all service is running using the following command:
kubectl --namespace=monitoring get all --selector=app=prometheus-blackbox-exporter
Test Blackbox exporter
You can access Blackbox exporter Web UI using port-forward :
kubectl --namespace=monitoring port-forward svc/prometheus-blackbox-exporter 9115:9115
Connect to Blackbox exporter Web UI via http://localhost:9115 using web browser.
If you visit http://localhost:9115/probe?module=http_2xx&target=https://www.google.com you will see the result of target URL(https://www.google.com).
For example, if the value of probe_success metrics is 1 , it means success. But 0 means failure.
Add Prometheus config
After deploying BlackBox exporter, write Prometheus scrape configuration in prometheus-additional.yaml.
- job_name: 'kube-api-blackbox'
scrape_interval: 1w
metrics_path: /probe
params:
module: [http_2xx]
static_configs:
- targets:
- https://www.google.com
- http://www.example.com
- https://prometheus.io
relabel_configs:
- source_labels: [__address__]
target_label: __param_target
- source_labels: [__param_target]
target_label: instance
- target_label: __address__
replacement: prometheus-blackbox-exporter:9115 # The blackbox exporter.
Generate Secret using the following command.
PROMETHEUS_ADD_CONFIG=$(cat prometheus-additional.yaml | base64)
cat << EOF | kubectl --namespace=monitoring apply -f -
apiVersion: v1
kind: Secret
metadata:
name: additional-scrape-configs
type: Opaque
data:
prometheus-additional.yaml: $PROMETHEUS_ADD_CONFIG
EOF
Specify additional-scrape-configs to Prometheus operator using additionalScrapeConfigs .
kubectl --namespace=monitoring edit prometheuses k8s
...
spec:
additionalScrapeConfigs:
key: prometheus-additional.yaml
name: additional-scrape-configs
Access Prometheus Web UI and verify metrics and targets.
kubectl --namespace=monitoring port-forward svc/prometheus-k8s 9090:9090
You’ll find Blackbox’s metrics and targets.
Add Alert rule
To receive alerts about Blackbox exporter, add alert rules to Prometheus operator.
kubectl --namespace=monitoring edit prometheusrules prometheus-k8s-rules
...
- name: blackbox-exporter
rules:
- alert: ProbeFailed
expr: probe_success == 0
for: 5m
labels:
severity: error
annotations:
summary: "Probe failed (instance {{ $labels.instance }})"
description: "Probe failed\n VALUE = {{ $value }}\n LABELS: {{ $labels }}"
- alert: SlowProbe
expr: avg_over_time(probe_duration_seconds[1m]) > 1
for: 5m
labels:
severity: warning
annotations:
summary: "Slow probe (instance {{ $labels.instance }})"
description: "Blackbox probe took more than 1s to complete\n VALUE = {{ $value }}\n LABELS: {{ $labels }}"
- alert: HttpStatusCode
expr: probe_http_status_code <= 199 OR probe_http_status_code >= 400
for: 5m
labels:
severity: error
annotations:
summary: "HTTP Status Code (instance {{ $labels.instance }})"
description: "HTTP status code is not 200-399\n VALUE = {{ $value }}\n LABELS: {{ $labels }}"
- alert: SslCertificateWillExpireSoon
expr: probe_ssl_earliest_cert_expiry - time() < 86400 * 30
for: 5m
labels:
severity: warning
annotations:
summary: "SSL certificate will expire soon (instance {{ $labels.instance }})"
description: "SSL certificate expires in 30 days\n VALUE = {{ $value }}\n LABELS: {{ $labels }}"
- alert: SslCertificateHasExpired
expr: probe_ssl_earliest_cert_expiry - time() <= 0
for: 5m
labels:
severity: error
annotations:
summary: "SSL certificate has expired (instance {{ $labels.instance }})"
description: "SSL certificate has expired already\n VALUE = {{ $value }}\n LABELS: {{ $labels }}"
- alert: HttpSlowRequests
expr: avg_over_time(probe_http_duration_seconds[1m]) > 1
for: 5m
labels:
severity: warning
annotations:
summary: "HTTP slow requests (instance {{ $labels.instance }})"
description: "HTTP request took more than 1s\n VALUE = {{ $value }}\n LABELS: {{ $labels }}"
- alert: SlowPing
expr: avg_over_time(probe_icmp_duration_seconds[1m]) > 1
for: 5m
labels:
severity: warning
annotations:
summary: "Slow ping (instance {{ $labels.instance }})"
description: "Blackbox ping took more than 1s\n VALUE = {{ $value }}\n LABELS: {{ $labels }}"
Navigate to Status => Rules on Prometheus Web UI and find blackbox-exporter alert rules.
Get alerted before Kubernetes API Server SSL certificates expire
Let’s setup the monitoring for Kubernetes API Server SSL certificates expire. It’ll send alerts once a week.
Add Blackbox exporter module for Kubernetes API Server Authentication
kubectl --namespace=monitoring edit configmap prometheus-blackbox-exporter
...
kube-api:
http:
method: GET
no_follow_redirects: false
preferred_ip_protocol: ip4
tls_config:
insecure_skip_verify: false
ca_file: /var/run/secrets/kubernetes.io/serviceaccount/ca.crt
bearer_token_file: /var/run/secrets/kubernetes.io/serviceaccount/token
valid_http_versions:
- HTTP/1.1
- HTTP/2
valid_status_codes: []
prober: http
timeout: 5s
Add Prometheus scrape configuration
- job_name: 'kube-api-blackbox'
metrics_path: /probe
params:
module: [kube-api]
static_configs:
- targets:
- https://kubernetes.default.svc/api
relabel_configs:
- source_labels: [__address__]
target_label: __param_target
- source_labels: [__param_target]
target_label: instance
- target_label: __address__
replacement: prometheus-blackbox-exporter:9115 # The blackbox exporter.
Apply Prometheus Secret
PROMETHEUS_ADD_CONFIG=$(cat prometheus-additional.yaml | base64)
cat << EOF | kubectl --namespace=monitoring apply -f -
apiVersion: v1
kind: Secret
metadata:
name: additional-scrape-configs
type: Opaque
data:
prometheus-additional.yaml: $PROMETHEUS_ADD_CONFIG
EOF
Add Alert rule
kubectl --namespace=monitoring edit prometheusrules prometheus-k8s-rules
...
- name: k8s-api-server-cert-expiry
rules:
- alert: K8sAPIServerSSLCertExpiringAfterThreeMonths
expr: probe_ssl_earliest_cert_expiry{job="kube-api-blackbox"} - time() < 86400 * 90
for: 1w
labels:
severity: warning
annotations:
summary: "Kubernetes API Server SSL certificate will expire after three months (instance {{ $labels.instance }})"
description: "Kubernetes API Server SSL certificate expires in 90 days\n VALUE = {{ $value }}\n LABELS: {{ $labels }}"