Enable forwarding IPv6 connections through the proxy (#12495)

As part of the ongoing effort to support IPv6/dual-stack networks, this change
enables the proxy to properly forward IPv6 connections:

- Adds the new `LINKERD2_PROXY_OUTBOUND_LISTEN_ADDRS` environment variable when
  injecting the proxy. This is supported as of proxy v2.228.0 which was just
  pulled into the linkerd2 repo in #2d5085b56e465ef56ed4a178dfd766a3e16a631d.
  This adds the IPv6 loopback address (`[::1]`) to the IPv4 one (`127.0.0.1`)
  so the proxy can forward outbound connections received via IPv6. The injector
  will still inject `LINKERD2_PROXY_OUTBOUND_LISTEN_ADDR` to support the rare
  case where the `proxy.image.version` value is overridden with an older
  version. The new proxy still considers that variable, but it's superseded by
  the new one. The old variable is considered deprecated and should be removed
  in the future.
- The values for `LINKERD2_PROXY_CONTROL_LISTEN_ADDR`,
  `LINKERD2_PROXY_ADMIN_LISTEN_ADDR` and `LINKERD2_PROXY_INBOUND_LISTEN_ADDR`
  have been updated to point to the IPv6 wildcard address (`[::]`) instead of
  the IPv4 one (`0.0.0.0`) for the same reason. Unlike with the loopback
  address, the IPv6 wildcard address suffices to capture both IPv4 and IPv6
  traffic.
- The endpoint translator's `getInboundPort()` has been updated to properly
  parse the IPv6 loopback address retrieved from the proxy container manifest.
  A unit test was added to validate the behavior.

charts/partials/templates/_proxy.tpl

@@ -76,13 +76,16 @@ env:
   value: "365d"
 {{ end -}}
 - name: LINKERD2_PROXY_CONTROL_LISTEN_ADDR
-  value: 0.0.0.0:{{.Values.proxy.ports.control}}
+  value: "[::]:{{.Values.proxy.ports.control}}"
 - name: LINKERD2_PROXY_ADMIN_LISTEN_ADDR
-  value: 0.0.0.0:{{.Values.proxy.ports.admin}}
+  value: "[::]:{{.Values.proxy.ports.admin}}"
+{{- /* Deprecated, superseded by LINKERD2_PROXY_OUTBOUND_LISTEN_ADDRS since proxy's v2.228.0 (deployed since edge-24.4.5) */}}
 - name: LINKERD2_PROXY_OUTBOUND_LISTEN_ADDR
-  value: 127.0.0.1:{{.Values.proxy.ports.outbound}}
+  value: "127.0.0.1:{{.Values.proxy.ports.outbound}}"
+- name: LINKERD2_PROXY_OUTBOUND_LISTEN_ADDRS
+  value: "127.0.0.1:{{.Values.proxy.ports.outbound}},[::1]:{{.Values.proxy.ports.outbound}}"
 - name: LINKERD2_PROXY_INBOUND_LISTEN_ADDR
-  value: 0.0.0.0:{{.Values.proxy.ports.inbound}}
+  value: "[::]:{{.Values.proxy.ports.inbound}}"
 - name: LINKERD2_PROXY_INBOUND_IPS
   valueFrom:
     fieldRef:

cli/cmd/testdata/inject-filepath/expected/injected_nginx.yaml

@@ -64,13 +64,15 @@ spec:
         - name: LINKERD2_PROXY_INBOUND_DISCOVERY_IDLE_TIMEOUT
           value: 90s
         - name: LINKERD2_PROXY_CONTROL_LISTEN_ADDR
-          value: 0.0.0.0:4190
+          value: '[::]:4190'
         - name: LINKERD2_PROXY_ADMIN_LISTEN_ADDR
-          value: 0.0.0.0:4191
+          value: '[::]:4191'
         - name: LINKERD2_PROXY_OUTBOUND_LISTEN_ADDR
           value: 127.0.0.1:4140
+        - name: LINKERD2_PROXY_OUTBOUND_LISTEN_ADDRS
+          value: 127.0.0.1:4140,[::1]:4140
         - name: LINKERD2_PROXY_INBOUND_LISTEN_ADDR
-          value: 0.0.0.0:4143
+          value: '[::]:4143'
         - name: LINKERD2_PROXY_INBOUND_IPS
           valueFrom:
             fieldRef:

cli/cmd/testdata/inject-filepath/expected/injected_nginx_redis.yaml

@@ -64,13 +64,15 @@ spec:
         - name: LINKERD2_PROXY_INBOUND_DISCOVERY_IDLE_TIMEOUT
           value: 90s
         - name: LINKERD2_PROXY_CONTROL_LISTEN_ADDR
-          value: 0.0.0.0:4190
+          value: '[::]:4190'
         - name: LINKERD2_PROXY_ADMIN_LISTEN_ADDR
-          value: 0.0.0.0:4191
+          value: '[::]:4191'
         - name: LINKERD2_PROXY_OUTBOUND_LISTEN_ADDR
           value: 127.0.0.1:4140
+        - name: LINKERD2_PROXY_OUTBOUND_LISTEN_ADDRS
+          value: 127.0.0.1:4140,[::1]:4140
         - name: LINKERD2_PROXY_INBOUND_LISTEN_ADDR
-          value: 0.0.0.0:4143
+          value: '[::]:4143'
         - name: LINKERD2_PROXY_INBOUND_IPS
           valueFrom:
             fieldRef:
@@ -295,13 +297,15 @@ spec:
         - name: LINKERD2_PROXY_INBOUND_DISCOVERY_IDLE_TIMEOUT
           value: 90s
         - name: LINKERD2_PROXY_CONTROL_LISTEN_ADDR
-          value: 0.0.0.0:4190
+          value: '[::]:4190'
         - name: LINKERD2_PROXY_ADMIN_LISTEN_ADDR
-          value: 0.0.0.0:4191
+          value: '[::]:4191'
         - name: LINKERD2_PROXY_OUTBOUND_LISTEN_ADDR
           value: 127.0.0.1:4140
+        - name: LINKERD2_PROXY_OUTBOUND_LISTEN_ADDRS
+          value: 127.0.0.1:4140,[::1]:4140
         - name: LINKERD2_PROXY_INBOUND_LISTEN_ADDR
-          value: 0.0.0.0:4143
+          value: '[::]:4143'
         - name: LINKERD2_PROXY_INBOUND_IPS
           valueFrom:
             fieldRef:

cli/cmd/testdata/inject-filepath/expected/injected_redis.yaml

@@ -64,13 +64,15 @@ spec:
         - name: LINKERD2_PROXY_INBOUND_DISCOVERY_IDLE_TIMEOUT
           value: 90s
         - name: LINKERD2_PROXY_CONTROL_LISTEN_ADDR
-          value: 0.0.0.0:4190
+          value: '[::]:4190'
         - name: LINKERD2_PROXY_ADMIN_LISTEN_ADDR
-          value: 0.0.0.0:4191
+          value: '[::]:4191'
         - name: LINKERD2_PROXY_OUTBOUND_LISTEN_ADDR
           value: 127.0.0.1:4140
+        - name: LINKERD2_PROXY_OUTBOUND_LISTEN_ADDRS
+          value: 127.0.0.1:4140,[::1]:4140
         - name: LINKERD2_PROXY_INBOUND_LISTEN_ADDR
-          value: 0.0.0.0:4143
+          value: '[::]:4143'
         - name: LINKERD2_PROXY_INBOUND_IPS
           valueFrom:
             fieldRef: