Using Resque-Scheduler with Docker-Compose - Error connecting to Redis on localhost:6379

I'm trying to run my rails app, resque and redis. Using foreman etc my setup works fine but when I try to run it in Docker using docker-compose I get:

app_1       | 21:03:13 resque.1 | Redis::CannotConnectError: Error connecting to Redis on redis://redis:6379 (SocketError)
app_1       | 21:03:13 resque.1 | Original Exception (Redis::CannotConnectError): Error connecting to Redis on redis://redis:6379 (SocketError)

My Dockerfile looks like:

FROM ruby:2.6.3-alpine

RUN apk update && apk add bash build-base libxml2-dev libxslt-dev postgresql postgresql-dev

VOLUME ["/code"]
WORKDIR /code

My Docker Compose YML looks like:

version: '3'
services:
  app:
    build: .
    command:
      - /bin/bash
      - -c
      - |
        bundle check || bundle install
        bundle exec rake db:migrate; rake db:seed
        bundle exec foreman start
    volumes:
      - ./:/code
    ports:
      - "5000:5000"
    depends_on:
      - redis
    environment:
      REDIS_URL: redis://redis/5
  redis:
    image: redis:5.0.5-alpine

My procfile:

web:       bundle exec puma -C config/puma.rb
resque:    bundle exec rake resque:work QUEUE=*
scheduler: bundle exec rake resque:scheduler

my config/initializers/resque.rb

redis_url = ENV["REDIS_URL"] || "redis://localhost:6379"

Redis.current = Redis.new(url: redis_url)
Resque.redis = Redis.current

and my lib/tasks/resque.rake

require "resque/tasks"
require "resque/scheduler/tasks"

task "resque:preload" => :environment
namespace :resque do
  task :setup do
    require "resque"

  end

  task setup_schedule: :setup do
    require "resque-scheduler"

    Resque.schedule = YAML.load_file(Rails.root.join("config","schedule.yml"))
  end

  task scheduler: :setup_schedule
end

UPDATE

The problem appears to be specifically with Resque-Scheduler. If I remove that from my procfile I can start my app fine with Docker-Compose and I can see perform resque jobs and see them running.

However the scheduler works fine when started with manually or with foreman (not using containers) so I'd like to be able to get it working here also.