Docker Swarm must have the minimum number of manager nodes.
An XCCDF Rule
Description
<VulnDiscussion>Ensure that the minimum number of required manager nodes is created in a swarm. Manager nodes within a swarm have control over the swarm and change its configuration modifying security parameters. Having excessive manager nodes could render the swarm more susceptible to compromise. If fault tolerance is not required in the manager nodes, a single node should be elected as a manger. If fault tolerance is required then the smallest practical odd number to achieve the appropriate level of tolerance should be configured.</VulnDiscussion><FalsePositives></FalsePositives><FalseNegatives></FalseNegatives><Documentable>false</Documentable><Mitigations></Mitigations><SeverityOverrideGuidance></SeverityOverrideGuidance><PotentialImpacts></PotentialImpacts><ThirdPartyTools></ThirdPartyTools><MitigationControl></MitigationControl><Responsibility></Responsibility><IAControls></IAControls>
- ID
- SV-235848r627671_rule
- Severity
- Medium
- References
- Updated
Remediation - Manual Procedure
If an excessive number of managers is configured, the excess can be demoted to worker using the following command:
docker node demote <ID>
Where is the node ID value of the manager to be demoted.