flannel/flannel-cni-plugin is pinned to old Alpine edge release

[bnevis-i]

Suggestion: if flannel/flannel-cni-plugin is going to be built from an edge release of Alpine, use FROM alpine:edge instead of FROM alpine:<oldtaghere>

The old FROM tag is causing the plugin to accumulate CVE's:

Trivy output:

$ trivy image -d flannel/flannel-cni-plugin:v1.4.0-flannel1

flannel/flannel-cni-plugin:v1.4.0-flannel1 (alpine 3.19_alpha20230901)

Total: 10 (UNKNOWN: 0, LOW: 2, MEDIUM: 6, HIGH: 2, CRITICAL: 0)

Offending code:

https://github.com/flannel-io/cni-plugin/blob/main/Dockerfile.image#L19

FROM alpine:20230901

[manuelbuil]

Thanks! We will add some automation bot to update the tag. Using edge is not recommended because we won't be able to reproduce potential problems since the version will be changing

[thomasferrandiz]

Version updated by dependabot here: #64