Elaborating

docs/health.md

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+# Health checks
+
+TBD

docs/metrics.md

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+# Metrics
+
+TBD

docs/scaling.md

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+# Scaling
+
+The ArangoDB operator supports up and down scaling of
+the number of dbservers & coordinators.
+
+Q: Agents as well?
+
+The scale up or down, change the number of servers in the custom
+resource and apply the updated resource using:
+
+```bash
+kubectl apply -f yourCustomResourceFile.yaml
+```
+
+## Internal process
+
+The internal process followed by the ArangoDB operator
+when scaling up is as follows:
+
+- Set CR state to `Scaling`
+- Create an additional server Pod
+- Wait until server is ready before continuing
+- Set CR state to `Ready`
+
+The internal process followed by the ArangoDB operator
+when scaling down a dbserver is as follows:
+
+- Set CR state to `Scaling`
+- Drain the dbserver (TODO fill in procedure)
+- Shutdown the dbserver such that it removes itself from the agency
+- Remove the dbserver Pod
+- Set CR state to `Ready`
+
+The internal process followed by the ArangoDB operator
+when scaling down a coordinator is as follows:
+
+- Set CR state to `Scaling`
+- Shutdown the coordinator such that it removes itself from the agency
+- Remove the coordinator Pod
+- Set CR state to `Ready`
+
+Note: Scaling is always done 1 server at a time.