updated IPV6 [] and testing

[peatey]

fix: use net.JoinHostPort for IPv6-safe kubelet scrape URLs

Fixes #164

Problem

directNode.formatEndpoint() constructs kubelet scrape URLs via fmt.Sprintf("https://%s:%v/%s", d.ip, d.port, s). On IPv6-only clusters, NodeAddress() returns a bare IPv6 address from the Kubernetes API (e.g. 2a05:d014:1314:704::a282), producing an invalid URL:

https://2a05:d014:1314:704::a282:10250/stats/summary

Go's net/url.Parse (called by http.NewRequest) interprets the colons as port delimiters and fails with invalid port ":d014:1314:..." after host. This silently breaks all node metrics scraping on IPv6-only clusters — the pod stays Running but cost allocation data is completely absent.

Per RFC 3986 §3.2.2, IPv6 literals in URIs must be enclosed in square brackets:

https://[2a05:d014:1314:704::a282]:10250/stats/summary

Fix

Replace bare string concatenation with net.JoinHostPort in pkg/nodes/request.go:

// Before
func (d directNode) formatEndpoint(s string) string {
    return fmt.Sprintf("https://%s:%v/%s", d.ip, d.port, s)
}
// After

func (d directNode) formatEndpoint(s string) string {

return fmt.Sprintf("https://%s/%s", net.JoinHostPort(d.ip, strconv.FormatInt(d.port, 10)), s)

}

net.JoinHostPort is the Go standard library's intended API for this — it wraps IPv6 addresses in brackets automatically and passes IPv4 addresses through unchanged. No behavioural change for existing IPv4 clusters.

Changes

• pkg/nodes/request.go — Added "net" and "strconv" imports; replaced fmt.Sprintf URL construction with net.JoinHostPort
• pkg/nodes/request_test.go (new) — Unit tests for formatEndpoint covering IPv4, full IPv6, loopback (::1), and ULA (fd00::1) addresses. Each test verifies the URL is parseable by net/url.Parse

Testing

go test ./pkg/nodes/... -v

All existing tests pass. New tests validate:

Input IP	Port	Expected Output
10.128.15.239	10250	https://10.128.15.239:10250/stats/summary
2a05:d014:1314:704::a282	10250	https://[2a05:d014:1314:704::a282]:10250/stats/summary
::1	10250	https://[::1]:10250/stats/summary
fd00::1	443	https://[fd00::1]:443/stats/summary

Impact

• IPv6-only clusters: Fixes complete loss of cost allocation data
• IPv4 clusters: No change — net.JoinHostPort is a no-op for IPv4
• Dual-stack clusters: Fix applies when NodeInternalIP resolves to an IPv6 address

# fix: use net.JoinHostPort for IPv6-safe kubelet scrape URLs

Fixes #164

Problem

directNode.formatEndpoint() constructs kubelet scrape URLs via fmt.Sprintf("https://%s:%v/%s", d.ip, d.port, s). On IPv6-only clusters, NodeAddress() returns a bare IPv6 address from the Kubernetes API (e.g. 2a05:d014:1314:704::a282), producing an invalid URL:

https://2a05:d014:1314:704::a282:10250/stats/summary

Go's net/url.Parse (called by http.NewRequest) interprets the colons as port delimiters and fails with invalid port ":d014:1314:..." after host. This silently breaks all node metrics scraping on IPv6-only clusters — the pod stays Running but cost allocation data is completely absent.

Per [RFC 3986 §3.2.2](https://www.rfc-editor.org/rfc/rfc3986#section-3.2.2), IPv6 literals in URIs must be enclosed in square brackets:

https://[2a05:d014:1314:704::a282]:10250/stats/summary

Fix

Replace bare string concatenation with net.JoinHostPort in pkg/nodes/request.go:

// Before
func (d directNode) formatEndpoint(s string) string {
    return fmt.Sprintf("https://%s:%v/%s", d.ip, d.port, s)
}

// After
func (d directNode) formatEndpoint(s string) string {
    return fmt.Sprintf("https://%s/%s", net.JoinHostPort(d.ip, strconv.FormatInt(d.port, 10)), s)
}

net.JoinHostPort is the Go standard library's intended API for this — it wraps IPv6 addresses in brackets automatically and passes IPv4 addresses through unchanged. No behavioural change for existing IPv4 clusters.

Changes

• pkg/nodes/request.go — Added "net" and "strconv" imports; replaced fmt.Sprintf URL construction with net.JoinHostPort
• pkg/nodes/request_test.go (new) — Unit tests for formatEndpoint covering IPv4, full IPv6, loopback (::1), and ULA (fd00::1) addresses. Each test verifies the URL is parseable by net/url.Parse

Testing

go test ./pkg/nodes/... -v

All existing tests pass. New tests validate:

Input IP	Port	Expected Output
10.128.15.239	10250	https://10.128.15.239:10250/stats/summary
2a05:d014:1314:704::a282	10250	https://[2a05:d014:1314:704::a282]:10250/stats/summary
::1	10250	https://[::1]:10250/stats/summary
fd00::1	443	https://[fd00::1]:443/stats/summary

Impact

• IPv6-only clusters: Fixes complete loss of cost allocation data
• IPv4 clusters: No change — net.JoinHostPort is a no-op for IPv4
• Dual-stack clusters: Fix applies when NodeInternalIP resolves to an IPv6 address

[thomasvn]

Is this necessary? I see that it's given an IPv6 address, but I don't feel we're really testing against it at all?

[thomasvn]

Left a minor comment, but overall LGTM!