feat: add eks_scale_node_group playbook action (#223)

[gerardrecinto]

Summary

Closes #223

Adds eks_scale_node_group — a playbook action that increases the maxSize of an EKS managed node group. Intended as a remediation step when the cluster autoscaler is blocked because the node group has reached its configured maximum.

New files:

• playbooks/robusta_playbooks/aws_node_group_actions.py — action + params model
• tests/test_aws_node_group_actions.py — 6 pytest unit tests

How it works

The action calls eks:DescribeNodegroup to read the current scaling config, then calls eks:UpdateNodegroupConfig to raise maxSize. minSize and desiredSize are left unchanged.

Params:

Param	Type	Description
cluster_name	str	EKS cluster name
region	str	AWS region (e.g. us-east-1)
node_group_name	str	Managed node group name
new_max_size	int	New maxSize — must exceed current value
aws_access_key_id	str (optional)	Falls back to instance role / environment
aws_secret_access_key	str (optional)	Falls back to instance role / environment

Example playbook config:

triggers:
  - on_prometheus_alert:
      alert_name: KubeNodeNotReady
actions:
  - eks_scale_node_group:
      cluster_name: my-cluster
      region: us-east-1
      node_group_name: workers
      new_max_size: 10

Required IAM permissions: eks:DescribeNodegroup, eks:UpdateNodegroupConfig

Test plan

• test_scale_up_succeeds — verifies update_nodegroup_config called with correct args and finding emitted
• test_no_op_when_new_max_not_larger — new_max_size < current max → no update, enrichment message returned
• test_no_op_when_new_max_is_equal — new_max_size == current max → no update
• test_raises_on_describe_failure — ClientError on describe → ActionException raised, update never called
• test_raises_on_update_failure — ClientError on update → ActionException raised
• test_boto_client_uses_explicit_credentials — explicit key/secret passed through to boto3

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[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

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Review profile: CHILL

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Reviewing files that changed from the base of the PR and between b107301 and a0adae6.

📒 Files selected for processing (1)

• tests/test_aws_node_group_actions.py

🚧 Files skipped from review as they are similar to previous changes (1)

• tests/test_aws_node_group_actions.py

---

Walkthrough

This PR adds a new EKS remediation action eks_scale_node_group that scales up managed node groups in Amazon EKS clusters. It defines the action parameters, implements the scaling logic with conditional updates, and includes comprehensive test coverage for success cases, no-op conditions, error handling, and credential wiring.

Changes

EKS Node Group Scaling

Layer / File(s)	Summary
Action contract and core implementation playbooks/robusta_playbooks/aws_node_group_actions.py	EksNodeGroupParams defines cluster name, region, node group name, new max size, and optional AWS credentials. The eks_scale_node_group action creates an EKS client, fetches current scaling configuration, returns early with enrichment if new max is not larger than current, otherwise updates the node group config while preserving min and desired sizes, logs the change, creates a finding, and wraps AWS client errors in ActionException.
Test fixtures, helpers, and validation cases tests/test_aws_node_group_actions.py	Test module with constants, error factory, and mock event fixture. Tests validate successful scaling updates and finding creation, no-op behavior when new max is less than or equal to current max, ActionException raised on describe and update failures, and correct boto3 client instantiation with explicit AWS credentials.

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~25 minutes

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly and concisely describes the main change: adding a new EKS node group scaling playbook action.
Description check	✅ Passed	The description is well-organized, explains the purpose, parameters, implementation details, and test plan—all directly related to the changeset.
Linked Issues check	✅ Passed	The PR fully implements the objective from issue #223 by adding a new playbook action for EKS managed node groups to increase their maximum size.
Out of Scope Changes check	✅ Passed	All changes are within scope: the action implementation, parameters model, and comprehensive unit tests directly support the objective to increase EKS node pool size limits.
Docstring Coverage	✅ Passed	Docstring coverage is 100.00% which is sufficient. The required threshold is 80.00%.

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✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

---

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[coderabbitai]

🧹 Nitpick comments (1)

playbooks/robusta_playbooks/aws_node_group_actions.py (1)

61-65: ⚡ Quick win

Preserve original exception context when re-raising.

Use explicit exception chaining in both except ClientError as e blocks (raise ... from e) so the root AWS error remains visible in tracebacks.

Proposed patch

     except ClientError as e:
         raise ActionException(
             ErrorCodes.ACTION_UNEXPECTED_ERROR,
             f"Failed to describe node group '{params.node_group_name}' "
             f"in cluster '{params.cluster_name}': {e}",
-        )
+        ) from e
@@
     except ClientError as e:
         raise ActionException(
             ErrorCodes.ACTION_UNEXPECTED_ERROR,
             f"Failed to update node group '{params.node_group_name}': {e}",
-        )
+        ) from e

Also applies to: 94-97

🤖 Prompt for AI Agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

In `@playbooks/robusta_playbooks/aws_node_group_actions.py` around lines 61 - 65,
The except ClientError as e handlers that raise ActionException should preserve
the original exception context by using explicit exception chaining; locate the
raise statements that construct ActionException with
ErrorCodes.ACTION_UNEXPECTED_ERROR (the blocks referencing
params.node_group_name and params.cluster_name and the later similar block at
lines 94-97) and change the re-raise to use "raise ActionException(... ) from e"
so the original AWS ClientError is retained in the traceback.

🤖 Prompt for all review comments with AI agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Nitpick comments:
In `@playbooks/robusta_playbooks/aws_node_group_actions.py`:
- Around line 61-65: The except ClientError as e handlers that raise
ActionException should preserve the original exception context by using explicit
exception chaining; locate the raise statements that construct ActionException
with ErrorCodes.ACTION_UNEXPECTED_ERROR (the blocks referencing
params.node_group_name and params.cluster_name and the later similar block at
lines 94-97) and change the re-raise to use "raise ActionException(... ) from e"
so the original AWS ClientError is retained in the traceback.

---

ℹ️ Review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro

Run ID: dd5c2ac7-227d-4783-8f36-07774d6f876d

📥 Commits

Reviewing files that changed from the base of the PR and between f945b48 and a12181d.

📒 Files selected for processing (2)

• playbooks/robusta_playbooks/aws_node_group_actions.py
• tests/test_aws_node_group_actions.py