Can't access running Docker container in browser - docker

Question

I'm working behind a corporate proxy. I'm on Windows 10 machine but I'm also running VMware. Inside VMware I'm running a Fedora 28 image. Because I'm behind a corporate proxy I have to run an NTLM proxy server on Windows 10 so that Fedora can connect to the internet.
I have everything set up and I can access the internet and pull docker images perfectly. I'm following this tutorial here on docker-compose.
This is my directory structure:
docker-compose-tut
├── commander
│ └── Dockerfile
└── docker-compose.yml
Dockerfile
FROM node:latest
ENV http_proxy=http://prx:3128
ENV https_proxy=http://prx:3128
ENV ftp_proxy=http://prx:3128
ENV no_proxy=localhost,127.0.0.1
RUN curl -L https://github.com/joeferner/redis-commander/tarball/v0.4.5 | tar zx
RUN npm install -g redis-commander
ENTRYPOINT ["redis-commander"]
CMD ["--redis-host", "redis"]
EXPOSE 8081
docker-compose.yml
backend:
image: redis:latest
restart: always
frontend:
build: commander
links:
- backend:redis
environment:
- ENV_VAR1 = some_value
ports:
- 8081:8081
environment:
- VAR1=value
restart: always
When I run the command docker-compose up -d I get the following output
[root#localhost docker-compose-tut]$ docker-compose up -d
Building frontend
Step 1/10 : FROM node:latest
---> b064644cf368
Step 2/10 : ENV http_proxy http://prx:3128
---> Using cache
---> f70ae2e24003
Step 3/10 : ENV https_proxy http://prx:3128
---> Using cache
---> 12a4e65a3874
Step 4/10 : ENV ftp_proxy http://prx:3128
---> Using cache
---> 77abdce2f8d7
Step 5/10 : ENV no_proxy localhost,127.0.0.1
---> Using cache
---> 467c4f25e4f7
Step 6/10 : RUN curl -L https://github.com/joeferner/redis-commander/tarball/v0.4.5 | tar zx
---> Using cache
---> e3f8b2d8ad64
Step 7/10 : RUN npm install -g redis-commander
---> Running in 3189b0fa1086
npm WARN deprecated ejs#0.8.8: Critical security bugs fixed in 2.5.5
When I enter the command docker-compose ps this is literally the output
Name Command State Ports
------------------------------
When I enter the command docker-compose --services the output is the following:
backend
frontend
If I open the browser and enter http://localhost:8081 the browser says that it can't establish a connection to http://localhost:8081.
What am I doing wrong?