I am not sure why the alexa API would cause a 502 when calling it. Have you restarted Home Assistant since adding the alexa
entry into your config?
Can you try hitting the Alexa API for another terminal addon (I used the VSCode addon)
curl -s -X POST -H "Authorization: Bearer ${SUPERVISOR_TOKEN}" -H "Content-Type: application/json" http://supervisor/core/api/alexa/smart_home -d '{
"directive": {
"header": {
"namespace": "Alexa.Discovery",
"name": "Discover",
"payloadVersion": "3",
"messageId": "1bd5d003-31b9-476f-ad03-71d471922820"
},
"payload": {
"scope": {
"type": "BearerToken"
}
}
}
}'
I also published a new version of the HA Skill addon (v1.0.4) that includes a debug option in the addon configuration. You can try enabling that to see if the addon logs show anything useful.