feat(istio): add configurable TLS version

- Introduced support for configuring the minimum TLS version for UDS Core.
- Added 'supportTLSV1_2' boolean flag in values file to allow selection between TLS 1.2 and TLS 1.3.
- Updated Helm templates to conditionally set 'minProtocolVersion' based on 'supportTLSV1_2' value.
- Ensured backward compatibility by defaulting to TLS 1.3.
- Commented and documented the new configuration option for clarity.

Closes defenseunicorns#599

Signed-off-by: jamestexas <[email protected]>

src/istio/chart/templates/gateway.yaml

@@ -32,7 +32,7 @@ spec:
         mode: {{ $server.mode }}
         {{- if ne $server.mode "PASSTHROUGH" }}
         credentialName: gateway-tls
-        minProtocolVersion: TLSV1_3
+        minProtocolVersion: {{ if .Values.tls.supportTLSV1_2 }}TLSV1_2{{ else }}TLSV1_3{{ end }}
         {{- end }}
     {{ end }}
 {{ end }}

src/istio/chart/values.yaml

@@ -5,6 +5,9 @@ name: change-me
 domain: "###ZARF_VAR_DOMAIN###"
 
 # tls:
+#   # Set to true to support TLS 1.2, false for TLS 1.3 only
+#   supportTLSV1_2: false
+
 #   # The TLS certificate for the gateway, if not in 'PASSTHROUGH' mode (base64 encoded)
 #   cert: ""