ray.init() will currently start a new Ray instance even if one is already existing, which is very confusing if you are a new user trying to go from local development to a cluster. This PR changes it so that, when no address is specified, we first try to find an existing Ray cluster that was created through `ray start`. If none is found, we will start a new one.
This makes two changes to the ray.init() resolution order:
1. When `ray start` is called, the started cluster address was already written to a file called `/tmp/ray/ray_current_cluster`. For ray.init() and ray.init(address="auto"), we will first check this local file for an existing cluster address. The file is deleted on `ray stop`. If the file is empty, autodetect any running cluster (legacy behavior) if address="auto", or we will start a new local Ray instance if address=None.
2. When ray.init(address="local") is called, we will create a new local Ray instance, even if one is already existing. This behavior seems to be necessary mainly for `ray.client` use cases.
This also surfaces the logs about which Ray instance we are connecting to. Previously these were hidden because we didn't set up the log until after connecting to Ray. So now Ray will log one of the following messages during ray.init:
```
(Connecting to existing Ray cluster at address: <IP>...)
...connection...
(Started a local Ray cluster.| Connected to Ray Cluster.)( View the dashboard at <URL>)
```
Note that this changes the dashboard URL to be printed with `ray.init()` instead of when the dashboard is first started.
Co-authored-by: Eric Liang <ekhliang@gmail.com>
To use Jobs on a remote cluster, you need to set up port forwarding. When using the cluster launcher, the `ray dashboard` command provides this automatically. This PR adds a how-to to the docs for this feature.
Co-authored-by: Edward Oakes <ed.nmi.oakes@gmail.com>
Address followup comments from https://github.com/ray-project/ray/pull/19863
- Add short "Concepts" section
- Add more section headings to break up the text
- Add "Workflow: Local Files" example
- Add "Workflow: Library development" example
* Small improvements to the Ray Cluster docs
* Update quickstart.rst
Changed title for quick start
Co-authored-by: Javier Redondo <javier@Anyscale-MacBook-Pro.local>
