Souin, Traefik and SSL

My Traefik configuration works with SSL. As soon as I put Souin in front of it, I get 502 bad gateway.

I guess it's because Traefik is 443 only, and Souin is looking at the docker hostname, http://traefik? I tried running wget https://traefik from the host but got an SSL client cert error. docker-compose file is attached. Any help is much appreciated:

version: '3.6'

services:
  traefik:
    image: 'traefik:v2.4'
    command:
      - '--log.level=DEBUG'
      - '--api.insecure=true'
      - '--providers.docker=true'
      - '--providers.docker.exposedbydefault=false'
      - '--entrypoints.websecure.address=:443'
      - '--certificatesresolvers.myresolver.acme.tlschallenge=true'
      - '--certificatesresolvers.myresolver.acme.email=<my email>'
      - '--certificatesresolvers.myresolver.acme.storage=/letsencrypt/acme.json'
    volumes:
      - './letsencrypt:/letsencrypt'
      - '/var/run/docker.sock:/var/run/docker.sock:ro'

  postgres:
    image: postgres:12
    restart: always
    volumes:
      - ./db_data:/var/lib/postgresql/data
    environment:
      POSTGRES_PASSWORD: postgrespassword

  graphql-engine:
    image: hasura/graphql-engine:v1.3.3
    depends_on:
      - 'postgres'
    restart: always
    environment:
      HASURA_GRAPHQL_DATABASE_URL: postgres://postgres:postgrespassword@postgres:5432/postgres
      ## enable the console served by server
      HASURA_GRAPHQL_ENABLE_CONSOLE: 'true' # set to "false" to disable console
      ## enable debugging mode. It is recommended to disable this in production
      HASURA_GRAPHQL_DEV_MODE: 'true'
      HASURA_GRAPHQL_ENABLED_LOG_TYPES: startup, http-log, webhook-log, websocket-log, query-log
      ## uncomment next line to set an admin secret
      # HASURA_GRAPHQL_ADMIN_SECRET: myadminsecretkey
    ports:
      - '8081:8080'
    labels:
      - 'traefik.enable=true'
      - 'traefik.http.routers.graphql-engine.rule=Host(`<my domain>`) && PathPrefix(`/v1/`)'
      - 'traefik.http.routers.graphql-engine.entrypoints=websecure'
      - 'traefik.http.routers.graphql-engine.tls.certresolver=myresolver'

  souin:
    image: darkweak/souin:latest
    ports:
      - 80:80
      - 443:443
    depends_on:
      - redis
    environment:
      GOPATH: /app
    volumes:
      - ./letsencrypt/acme.json:/ssl/traefik.json

  redis:
    image: redis:alpine

Look that way from the brief look I took. As they are fronting traefik you'll have to configure it they way they say for it to work.

As a wild guess use port 80, and change the acme challenge to HTTP-01