Add DigitalOcean service discovery (#7407)

Signed-off-by: Julien Pivotto <roidelapluie@inuits.eu>

documentation/examples/prometheus-digitalocean.yml

@@ -0,0 +1,25 @@
+# A example scrape configuration for running Prometheus with
+# DigitalOcean.
+
+scrape_configs:
+  
+  # Make Prometheus scrape itself for metrics.
+  - job_name: 'prometheus'
+    static_configs:
+    - targets: ['localhost:9090']
+
+  # Discover Node Exporter instances to scrape.
+  - job_name: 'node'
+
+    digitalocean_sd_configs:
+      - bearer_token: "<replace with a Personal Access Token>"
+    relabel_configs:
+      # Only scrape targets that have a tag 'monitoring'.
+      - source_labels: [__meta_digitalocean_tags]
+        regex: '.*,monitoring,.*'
+        action: keep
+
+      # Use the public IPv6 address and port 9100 to scrape the target.
+      - source_labels: [__meta_digitalocean_public_ipv6]
+        target_label: __address__
+        replacement: '[$1]:9100'