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plugin_agent_nodeattestor_k8s_sat.md

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Agent plugin: NodeAttestor "k8s_sat"

Must be used in conjunction with the server-side k8s_sat plugin

The k8s_sat plugin attests nodes running in inside of Kubernetes. The agent reads and provides the signed service account token to the server.

Note: If your cluster supports Service Account Token Volume Projection you should instead consider using the k8s_psat attestor due to the security considerations below.

The server-side k8s_sat plugin generates a one-time UUID and generates a SPIFFE ID with the form:

spiffe://<trust domain>/spire/agent/k8s_sat/<cluster>/<UUID>

The main configuration accepts the following values:

Configuration Description Default
cluster Name of the cluster. It must correspond to a cluster configured in the server plugin.
token_path Path to the service account token on disk "/run/secrets/kubernetes.io/serviceaccount/token"

The token path defaults to the default location kubernetes uses to place the token and should not need to be overriden in most cases.

A sample configuration with the default token path:

    NodeAttestor "k8s_sat" {
        plugin_data {
            cluster = "MyCluster"
        }
    }

Security Considerations

At this time, the service account token does not contain claims that could be used to strongly identify the node/daemonset/pod running the agent. This means that any container running in a whitelisted service account can masquerade as an agent, giving it access to any identity the agent is capable of issuing. It is STRONGLY recommended that agents run under a dedicated service account.

It should be noted that due to the fact that SPIRE can't positively identify a node using this method, it is not possible to directly authorize identities for a distinct node or sets of nodes. Instead, this must be accomplished indirectly using a service account and deployment that leverages node affinity or node selectors.