Use the macsec_enabled flag in platform to enable macesc feature state

Author: judyjoseph

device/arista/x86_64-arista_7800r3a_36d2_lc/platform_env.conf

@@ -1,2 +1,3 @@
 usemsi=1
 dmasize=64M
+macsec_enabled=1

device/nokia/x86_64-nokia_ixr7250e_36x400g-r0/platform_env.conf

@@ -1,3 +1,4 @@
 usemsi=1
 dmasize=512M
 default_mtu=9100
+macsec_enabled=1

files/build_templates/init_cfg.json.j2

@@ -52,7 +52,7 @@
 {%- if include_p4rt == "y" %}{% do features.append(("p4rt", "enabled", false, "enabled")) %}{% endif %}
 {%- if include_restapi == "y" %}{% do features.append(("restapi", "enabled", false, "enabled")) %}{% endif %}
 {%- if include_sflow == "y" %}{% do features.append(("sflow", "disabled", false, "enabled")) %}{% endif %}
-{%- if include_macsec == "y" %}{% do features.append(("macsec", "disabled", false, "enabled")) %}{% endif %}
+{%- if include_macsec == "y" %}{% do features.append(("macsec", "{% if 'type' in DEVICE_METADATA['localhost'] and DEVICE_METADATA['localhost']['type'] == 'SpineRouter' and MACSEC_SUPPORTED %}enabled{% else %}disabled{% endif %}", false, "enabled")) %}{% endif %}
 {%- if include_system_telemetry == "y" %}{% do features.append(("telemetry", "enabled", true, "enabled")) %}{% endif %}
     "FEATURE": {
 {# has_timer field if set, will start the feature systemd .timer unit instead of .service unit #}

src/sonic-py-common/sonic_py_common/device_info.py

@@ -654,3 +654,29 @@ def is_fast_reboot_enabled():
         fb_system_state = stdout.rstrip('\n')
 
     return fb_system_state
+
+
+# Check if this platform has macsec capability.
+def is_macsec_supported():
+    supported = 0
+    platform_env_conf_file_path = get_platform_env_conf_file_path()
+
+    # platform_env.conf file not present for platform
+    if platform_env_conf_file_path is None:
+        return supported
+
+    # Else open the file check for keyword - macsec_enabled -
+    with open(platform_env_conf_file_path) as platform_env_conf_file:
+        for line in platform_env_conf_file:
+            tokens = line.split('=')
+            if len(tokens) < 2:
+               continue
+            if tokens[0].lower() == 'macsec_enabled':
+                supported = tokens[1].strip()
+                break
+    return int(supported)
+
+
+def get_macsec_support_metadata():
+    macsec_support_metadata = {'MACSEC_SUPPORTED': True if is_macsec_supported() else False}
+    return macsec_support_metadata