ragserver: start adding new example of a RAG server in Go

Change-Id: I256449c9cd97ef53251e326d943858c237b4ea16
Reviewed-on: https://go-review.googlesource.com/c/example/+/608055
Reviewed-by: Ian Lance Taylor <[email protected]>
Auto-Submit: Eli Bendersky <[email protected]>
TryBot-Bypass: Eli Bendersky <[email protected]>
Reviewed-by: Eli Bendersky <[email protected]>

ragserver/README.md

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+# ragserver
+
+*RAG stands for Retrieval Augmented Generation*
+
+Demos of implementing a "RAG Server" in Go, using [Google
+AI](https://ai.google.dev/) for embeddings and language models and
+[Weaviate](https://weaviate.io/) as a vector database.
+
+
+## How it works
+
+The server we're developing is a standard Go HTTP server, listening on a local
+port. See the next section for the request schema for this server. It supports
+adding new documents to its context, and getting queries that would use this
+context.
+
+Weaviate has the be installed locally; the easiest way to do so is by using
+`docker-compose` as described in the Usage section.
+
+## Server request schema
+
+```
+/add/: POST {"documents": [{"text": "..."}, {"text": "..."}, ...]}
+  response: OK (no body)
+
+/query/: GET {"content": "..."}
+  response: model response as a string
+```
+
+## Server variants
+
+* `ragserver`: uses the Google AI Go SDK directly for LLM calls and embeddings,
+  and the Weaviate Go client library directly for interacting with Weaviate.
+
+## Usage
+
+* In terminal window 1, `cd tests` and run `docker-compose up`;
+  This will start the weaviate service in the foreground.
+* In terminal window 2, run `GEMINI_API_KEY=... go run .` in the tested
+  `ragserver` directory.
+* In terminal window 3, we can now run scripts to clear/populate the
+  weaviate DB and interact with `ragserver`. The following instructions are
+  for terminal window 3.
+
+Run `cd tests`; then we can clear out the weaviate DB with
+`./weaviate-delete-objects.sh`. To add documents to the DB through `ragserver`,
+run `./add-documents.sh`. For a sample query, run `./query.sh`
+Adjust the contents of these scripts as needed.
+
+## Environment variables
+
+* `SERVERPORT`: the port this server is listening on (default 9020)
+* `WVPORT`: the port Weaviate is listening on (default 9035)
+* `GEMINI_API_KEY`: API key for the Gemini service at https://ai.google.dev

ragserver/ragserver/go.mod

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+module golang.org/x/example/ragserver/ragserver
+
+go 1.23.0
+
+require (
+	github.com/google/generative-ai-go v0.17.0
+	github.com/weaviate/weaviate v1.26.1
+	github.com/weaviate/weaviate-go-client/v4 v4.15.1
+	google.golang.org/api v0.194.0
+)
+
+require (
+	cloud.google.com/go v0.115.1 // indirect
+	cloud.google.com/go/ai v0.8.0 // indirect
+	cloud.google.com/go/auth v0.9.1 // indirect
+	cloud.google.com/go/auth/oauth2adapt v0.2.4 // indirect
+	cloud.google.com/go/compute/metadata v0.5.0 // indirect
+	cloud.google.com/go/longrunning v0.5.7 // indirect
+	github.com/PuerkitoBio/purell v1.1.1 // indirect
+	github.com/PuerkitoBio/urlesc v0.0.0-20170810143723-de5bf2ad4578 // indirect
+	github.com/asaskevich/govalidator v0.0.0-20230301143203-a9d515a09cc2 // indirect
+	github.com/felixge/httpsnoop v1.0.4 // indirect
+	github.com/go-logr/logr v1.4.2 // indirect
+	github.com/go-logr/stdr v1.2.2 // indirect
+	github.com/go-openapi/analysis v0.21.2 // indirect
+	github.com/go-openapi/errors v0.22.0 // indirect
+	github.com/go-openapi/jsonpointer v0.19.5 // indirect
+	github.com/go-openapi/jsonreference v0.19.6 // indirect
+	github.com/go-openapi/loads v0.21.1 // indirect
+	github.com/go-openapi/spec v0.20.4 // indirect
+	github.com/go-openapi/strfmt v0.23.0 // indirect
+	github.com/go-openapi/swag v0.22.3 // indirect
+	github.com/go-openapi/validate v0.21.0 // indirect
+	github.com/golang/groupcache v0.0.0-20210331224755-41bb18bfe9da // indirect
+	github.com/google/s2a-go v0.1.8 // indirect
+	github.com/google/uuid v1.6.0 // indirect
+	github.com/googleapis/enterprise-certificate-proxy v0.3.2 // indirect
+	github.com/googleapis/gax-go/v2 v2.13.0 // indirect
+	github.com/josharian/intern v1.0.0 // indirect
+	github.com/mailru/easyjson v0.7.7 // indirect
+	github.com/mitchellh/mapstructure v1.5.0 // indirect
+	github.com/oklog/ulid v1.3.1 // indirect
+	github.com/pkg/errors v0.9.1 // indirect
+	go.mongodb.org/mongo-driver v1.14.0 // indirect
+	go.opencensus.io v0.24.0 // indirect
+	go.opentelemetry.io/contrib/instrumentation/google.golang.org/grpc/otelgrpc v0.51.0 // indirect
+	go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp v0.51.0 // indirect
+	go.opentelemetry.io/otel v1.26.0 // indirect
+	go.opentelemetry.io/otel/metric v1.26.0 // indirect
+	go.opentelemetry.io/otel/trace v1.26.0 // indirect
+	golang.org/x/crypto v0.26.0 // indirect
+	golang.org/x/net v0.28.0 // indirect
+	golang.org/x/oauth2 v0.22.0 // indirect
+	golang.org/x/sync v0.8.0 // indirect
+	golang.org/x/sys v0.24.0 // indirect
+	golang.org/x/text v0.17.0 // indirect
+	golang.org/x/time v0.6.0 // indirect
+	google.golang.org/genproto/googleapis/api v0.0.0-20240725223205-93522f1f2a9f // indirect
+	google.golang.org/genproto/googleapis/rpc v0.0.0-20240814211410-ddb44dafa142 // indirect
+	google.golang.org/grpc v1.65.0 // indirect
+	google.golang.org/protobuf v1.34.2 // indirect
+	gopkg.in/yaml.v3 v3.0.1 // indirect
+)