Assignment 5: Deploying Microservices via Docker Compose

Total points = 20

You will be required to create 2 Dockerfile and 1 docker-compose.yml files.  You will need to show the output of all the Docker and docker-compose commands, plus run the client script (testclient.sh) to demonstrate successful file operations.  Submit only text files showing your work.

This homework will be based on two Go programs named frontend.go and backend.go.  These will be compiled into two binaries; frontend and backend.  There will be 1 frontend and 3 backed microservice binaries running. The frontend will send RPC requests to one of the 3 backends. And each backend will send corresponding RPC responses to the frontend. In addition the 3 backends will each send periodic UDP beacon messages to the frontend, so that the frontend can dynamically discover each of the backends' IP addresses.

These microservices will provide a simple file storage system to create/write, read, list and delete files. The backend microservices provide a distributed storage system, each with their own volume filesystem. The single frontend microservice provides a simple HTTP (over TCP) REST API to perform the file operations and to write a file to a randomly selected backend microservice using the Gorilla framework.  The REST API will have a structured URL and use JSON payloads for a file's contents and related information about it. 

Below is the homework's directory tree that is formed when the HW5.zip archive is unzipped and all
dynamically created files are built.

.
├── compose
│   ├── backend -> ../images/backend    <<-- Link to images subdirectory for the backend microservice.
│   ├── docker-compose.yml              <<-- YOU NEED TO WRITE THE CONTENTS OF THIS FILE.
│   └── frontend -> ../images/frontend  <<-- Link to images subdirectory for the frontend microservice.
├── images
│   ├── backend
│   │   ├── Dockerfile    <<-- YOU NEED TO WRITE THE CONTENTS OF THIS FILE.
│   │   ├── config.txt    <<-- This is copied from the src/etc directory by a buildall.*.sh script.
│   │   └── files
│   └── frontend
│       ├── Dockerfile    <<-- YOU NEED TO WRITE THE CONTENTS OF THIS FILE.
│       └── config.txt    <<-- This is copied from the src/etc directory by a buildall.*.sh script.
├── scripts                  <<-- YOU NEED TO RUN THESE SCRIPTS TO SETUP AND BUILD THE CONTAINERS.
│   ├── buildall.again.sh    <<-- This builds the two images using the 2 dockerfiles after the first time.
│   ├── buildall.initial.sh  <<-- This builds the two images using the 2 dockerfiles for the first time.
│   ├── cleanall.sh          <<-- This deletes the two images.
│   └── setup.sh             <<-- This creates links between compose and images subdirectories.
└── src
    ├── backend           
    │   ├── backend       <<-- This is a dynamically compiled binary created by buildall.*.sh.
    │   ├── backend.go    <<-- This is the backend microservice source code.
    │   └── go.mod        <<-- This is dynamically created by buildall.initial.sh script.
    ├── client
    │   └── testclient.sh <<-- USE THIS SCRIPT TO SEND REST COMMANDS TO THE FRONTEND MICROSERVICE.
    ├── contract
    │   ├── entities.go   <<-- This is used by the rpc protocol communications between microservices.
    │   └── go.mod        <<-- This is dynamically created by buildall.initial.sh script.
    ├── etc
    │   └── config.txt    <<-- This is used to configure network information used by the microservices.
    ├── frontend
    │   ├── frontend      <<-- This is a dynamically compiled binary created by buildall.*.sh.
    │   ├── frontend.go   <<-- This is the frontend microservice.
    │   ├── go.mod        <<-- This is dynamically created by buildall.initial.sh script.
    │   └── go.sum        <<-- This is dynamically created by buildall.initial.sh script.
    ├── gorilla           <<-- This is the Gorilla REST API framework used by frontend microservice.
    │   ├── context
    │   │   ├── LICENSE
    │   │   ├── README.md
    │   │   ├── context.go
    │   │   ├── context_test.go
    │   │   └── doc.go
    │   └── mux
    │       ├── AUTHORS
    │       ├── LICENSE
    │       ├── README.md
    │       ├── bench_test.go
    │       ├── doc.go
    │       ├── example_authentication_middleware_test.go
    │       ├── example_cors_method_middleware_test.go
    │       ├── example_route_test.go
    │       ├── go.mod
    │       ├── middleware.go
    │       ├── middleware_test.go
    │       ├── mux.go
    │       ├── mux_httpserver_test.go
    │       ├── mux_test.go
    │       ├── old_test.govi
    │       ├── regexp.go
    │       ├── regexp_test.go
    │       ├── route.go
    │       └── test_helpers.go
    └── lib
        ├── config.go     <<-- This is used by both microservices to read the config.txt file above.
        └── go.mod        <<-- This is dynamically created by buildall.initial.sh script.

 

STEPS:
1. "Run HW5/scripts/setup.sh"
2. Create HW5/image/backend/Dockerfile
3. Create HW5/image/backend/Dockerfile
4. Run "HW5/scripts/buildall.initial.sh"  (buildall.again.sh can be used for 2nd and later runs)
5. Create HW5/compose/docker-compose.yml
   a. Frontend container's entry point is "/dockerclass/frontend".
      The frontend service must be named "frontend" so that the backend servers can
      use this DNS name to resolve its IP address.
   b. Backend container's entry point is "/dockerclass/backend".
      The backend services should be named "backend1", "backend2", and "backend3".
   c. Must contain shared bridge network named "dclassnet" 
      It is of driver type "bridge".  
      Subnet = 10.0.0.0/24
      The frontend container must map its port 8888 to the host's port 8888
   d. Must contain 3 volumes
      Each is of driver type "local"
      One per backend container, named "dclassvol1", "dclassvol2", and "dclassvol3". 
      The mount point inside each backend container is "/files".
6. Run "docker-compose up &"
7. Run "HW5/src/client/testclient.sh"
8. Run "docker container ls".
9. Run "docker image ls".
10. Run "docker volume ls".
11. Run "docker network ls".
12. Run "docker-compose down"
13. Run "HW5/scripts/cleanall.sh"

SUBMIT:
1. docker-compose.yml file
   See STEPS 5.a,b,c,d above.
2. Two Dockerfile files, one for backend and the other for frontend images.
   See STEPS 2 and 3 above.
3. All text output from STEPS 1-13 above.
4. And answer the following questions.
   a. If the 3 backend containers use 1 shared volume what would happen? Would files get mixed up?
      Submit a modified docker-compose.yml file with only 1 shared volume named "dclassvol".
      Submit results of running the "HW5/src/client/testclient.sh"
      Submit the results of "docker container ls".
      Submit the results of "docker image ls".
      Submit the results of "docker volume ls".
      Submit the results of "docker network ls".
   b. If the shared network is of driver type "host" what would happen?  
      Could you still run all 3 backends? Explain why or why not?
      Submit a modified docker-compose.yml file using the "host" network.
      Submit results of running the "HW5/src/client/testclient.sh"
      Submit the results of "docker container ls".
      Submit the results of "docker image ls".
      Submit the results of "docker volume ls".
      Submit the results of "docker network ls".

DEBUGGING:
Use docker exec or docker logs to debug your containers.