hello-world-grpc-client-java

Hello World gRPC Java client for Patina Network

The UI is a single frontend/index.html (Tailwind from a CDN, no build step), packaged into the jar at build time and served by the backend.

Prerequisites

• JDK 26 or newer (brew.sh)
• Maven (brew.sh)
• just (brew.sh)
• Tailscale, connected to the Patina VPN (brew.sh)
• Docker, only for just docker-build (brew.sh)

The Patina VPN is required to download the hello-world-grpc-service client library and to reach the staging gRPC service.

Note

You must be connected to the VPN to connect locally. You can find the instructions to connect at https://docs.patinanetwork.org/infra/how-to-connect-to-vpn/

Development

just run            # run the backend + UI on :8080 against the staging gRPC service
just test           # unit tests and coverage report
just lint           # spotless, checkstyle, and compile
just fmt            # apply formatting
just docker-build

Environment variables

Variable	Default	Description
HELLO_WORLD_SERVICE_GRPC_HOST	hello-world-grpc-service:50051	host:port of the hello-world gRPC service
HELLO_WORLD_SERVICE_GRPC_TLS	false	Connect to the gRPC service over TLS
HELLO_WORLD_SERVICE_GRPC_TIMEOUT_MS	3000	Deadline for each gRPC call, in milliseconds
HTTP_HOST	0.0.0.0	Address the HTTP server binds to
HTTP_PORT	8080	Port the HTTP server listens on
VERSION	N/A	Version string returned by GET /version
HELLO_WORLD_CLIENT_URLS	none	Comma-separated URLs returned by GET /urls and listed in the UI
ENVIRONMENT	none	production or staging switches logs to JSON (ECS); anything else logs human-readable
SPRING_PROFILES_ACTIVE	none	Set to local to use application-local.yaml

just run uses the local Spring profile (src/main/resources/application-local.yaml), which points at staging over TLS.

Releases

On main, CI creates an unprefixed semantic-version tag after both image builds succeed, using GitHub App credentials. Tags start at 1.0.0 and increment the patch version; source package versions are unchanged.

The tag triggers CD. Because the tagging step creates a new commit, CD promotes images built from its parent commit to the release tag and latest, then deploys production using the release tag. CI deploys only staging; production deployment runs only in CD.