[Prototype] RESTful API for core

[Michaelvll]

This is a prototype for client-server architecture.

Architecture

We now refactors the interface to 3 categories:

1. Restful API
2. SDK
3. CLI

Features

This is a list of features added (to be updated)

1. API server CLI (it can be started automatically): sky api start; sky api stop; sky api logs
2. sky status (through HTTP request)
3. Automatic cluster status update periodically
4. Async launch

$ curl -i -X POST http://127.0.0.1:8000/launch \
     -H "Content-Type: application/json" \
     -d '{"task": "resources:\n  cloud: aws\n  cpus: 2", "cluster_name": "test-10"}'

...
x-request-id: 7f6f0287-2448-42b8-bb0a-b9592b51eb1c

7. Show all requests

$ curl -i -X GET http://127.0.0.1:8000/requests

[{"request_id":"7f6f0287-2448-42b8-bb0a-b9592b51eb1c","request_name":"launch","status":"RUNNING","return_value":null,"log_path":null,"pid":53345}]%  

8. Wait for request and get the result

curl -i -X GET http://127.0.0.1:8000/get \
     -H "Content-Type: application/json" \                                         
     -d '{"request_id": "7f6f0287-2448-42b8-bb0a-b9592b51eb1c"}'

9. Abort a request

curl -i -X POST http://127.0.0.1:8000/abort \
     -H "Content-Type: application/json" \
     -d '{"request_id": "7f6f0287-2448-42b8-bb0a-b9592b51eb1c"}'

10. Stream the logs for a request

curl -i -X GET http://127.0.0.1:8000/stream \
     -H "Content-Type: application/json" \                                         
     -d '{"request_id": "7f6f0287-2448-42b8-bb0a-b9592b51eb1c"}'

TODOs

• [ ] Stream logs for a request
  • [x] Stream logs
  • [ ] Fix the spinner for launching (rich.status)
• [ ] Restful APIs
  • [ ] launch
    • [x] Basic support without file mounts
    • [x] Fix log tailing in sky launch
    • [ ] Design and support direct ssh
    • [ ] Support file mounts (automatically upload to the bucket and download to the VM)
• [ ] Refine UX

Tested (run the relevant ones):

• [ ] Code formatting: bash format.sh
• [ ] Any manual or new tests for this PR (please specify below)
• [ ] All smoke tests: pytest tests/test_smoke.py
• [ ] Relevant individual smoke tests: pytest tests/test_smoke.py::test_fill_in_the_name
• [ ] Backward compatibility tests: bash tests/backward_comaptibility_tests.sh