Blackbox-Exporter.md

+The Blackbox Exporter allows probing of web endpoints, for example: web certificate expiry, certificate validity, HTTP response. The configuration of endpoints is done in Prometheus' `scrape_config.yml`.
+
+Basic pre-configured Blackbox modules are:
+
+* http_2xx - Looks for a 200 HTTP response
+* http_post_2xx - Looks for a 200 HTTP response using POST method
+* tcp_connect - Probes by tcp
+* http_ssl - HTTP probe for certificate validity
+
+To probe an endpoint Prometheus has to have targets which to probe - the following is an example of what the Prometheus scrape config should include.\
+`<your_project>/<your_environment>/prometheus/scrape_config.yml`
+
+```
+scrape_configs:
+  - job_name: ssl_cert_validity
+    metrics_path: /probe # This should always be /probe for the blackbox exporter.
+    params:
+      module:
+      - http_ssl # Module as described above, in this case we're checking certificates
+    relabel_configs:
+    - source_labels:
+      - __address__
+      target_label: __param_target
+    - source_labels:
+      - __param_target
+      target_label: instance
+    - replacement: blackbox-exporter:9115
+      target_label: __address__
+    static_configs:
+    - targets:
+      - https://<your_url_here>.ee # There can be multiple targets under the same job
+```
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