Improve documentation for the Buildbarn example

Add instructions for a simple local Buildbarn deployment to test with.

Author: stagnation

examples/remote_execution/buildbarn/.buckconfig

@@ -2,14 +2,12 @@
 root = .
 prelude = prelude
 
-[buck2]
-digest_algorithms = SHA256
-
 [buck2_re_client]
-action_cache_address = http://localhost:8980
-engine_address = http://localhost:8980
-cas_address = http://localhost:8980
+action_cache_address = grpc://localhost:8980
+engine_address = grpc://localhost:8980
+cas_address = grpc://localhost:8980
 tls = false
+instance_name = fuse
 
 [build]
   execution_platforms = root//platforms:platforms

examples/remote_execution/buildbarn/README.md

@@ -1,30 +1,63 @@
-## Remote execution integration with Build Barn
+## Remote execution integration with Buildbarn
 
-This project provides a small example of what a project that utilizes [Build Barn](https://github.com/buildbarn) for RE might look like.
+This project provides a small example of what a project that utilizes [Buildbarn](https://github.com/buildbarn).
 
 In this document, we will go over the key configs used in this setup.
+Using a local docker-compose deployment from the [example deployment repo](https://github.com/buildbarn/bb-deployments).
+If you already have a Buildbarn deployment you can skip that.
 
-### Relevant configs in .buckconfig
+### Deploy a local Buildbarn
 
-First, the Build Barn endpoint and certificate should be configured as the following:
+```
+... $ git clone https://github.com/buildbarn/bb-deployments
+... $ cd bb-deployments
+.../bb-deployments $ cd docker-compose
+.../bb-deployments/docker-compose $ ./run.sh
+```
 
-```ini
-[buck2_re_client]
-engine_address       = $BB_ENDPOINT
-action_cache_address = $BB_ENDPOINT
-cas_address          = $BB_ENDPOINT
+This uses `docker-compose` to spin up the required Buildbarn services.
+Using FUSE based workers, those are generally the fastest as they can load action files on demand
+and avoids the overhead of setting up the full input root up front.
+In practice many actions do not read all the files in the input root.
+
+If you do not want FUSE workers you can instead switch to hardlinking workers
+The example deployments have two worker kinds "fuse", and "hardlinking",
+you can see the queues in the Buildbarn scheduler, http://localhost:7982.
+
+```
+Buildbarn Scheduler
+
+...
+
+Instance name                                    Platform properties                                    Size  Timeo
+   prefix                                                                                               class
+
+"fuse"        OSFamily="Linux" container-image="docker://ghcr.io/catthehacker/                          0     ∞
+              ubuntu:act-22.04@sha256:5f9c35c25db1d51a8ddaae5c0ba8d3c163c5e9a4a6cc97acd409ac7eae239448"
+"hardlinking" OSFamily="Linux" container-image="docker://ghcr.io/catthehacker/                          0     ∞
+              ubuntu:act-22.04@sha256:5f9c35c25db1d51a8ddaae5c0ba8d3c163c5e9a4a6cc97acd409ac7eae239448"
 ```
 
-If you're using the Docker-compose setup, the endpoint would be `http://localhost:8980` for all 3 of those.
+More information is available in the [repo](https://github.com/buildbarn/bb-deployments).
+
+### Relevant configs in .buckconfig
+
+First, the Buildbarn endpoint should be configured as the following:
 
-Additionally, set the `digest_algorithm` config to `SHA256`.
 ```ini
-[buck2]
-digest_algorithms = SHA256
+[buck2_re_client]
+engine_address       = grpc://localhost:8980
+action_cache_address = grpc://localhost:8980
+cas_address          = grpc://localhost:8980
+tls                  = false
+
+# Select the instance name, "fuse" or "hardlinking", without quotes
+instance_name        = fuse
 ```
 
-### Relevant configs in `ExecutionPlatformInfo`
+TLS is not used in this example.
 
-Build Barn takes in a Docker image and OSFamily  in its RE properties to select a worker.
+### Relevant configs in `ExecutionPlatformInfo`
 
-The execution platform used in this project `root//platforms:platforms` do so.
+Buildbarn takes in a Docker image and `OSFamily` in its RE properties to select a worker.
+This is configured in `root//platforms:platforms`.

examples/remote_execution/buildbarn/platforms/defs.bzl

@@ -18,7 +18,7 @@ def _platforms(ctx):
             local_enabled = True,
             remote_enabled = True,
             use_limited_hybrid = True,
-            # Set those up based on what workers you've registered with Build Barn.
+            # Set those up based on what workers you've registered with Buildbarn.
             remote_execution_properties = {
                 "OSFamily": "Linux",
                 "container-image": "docker://ghcr.io/catthehacker/ubuntu:act-22.04@sha256:5f9c35c25db1d51a8ddaae5c0ba8d3c163c5e9a4a6cc97acd409ac7eae239448",