Fix deploy-validator script to use remote Docker images by default (#4583)

## Summary

This PR updates the `deploy-validator.sh` script and Docker Compose
configuration to use pre-built Docker images from the official registry
by default, instead of building locally.

## Problem

Previously, the default `LINERA_IMAGE` in the script was just `linera`,
which assumed a locally built image. This caused issues when validators
tried to deploy without explicitly building the image first.

## Solution

### Changes Made:

1. **`scripts/deploy-validator.sh`**:
- Changed default behavior to use remote images from
`us-docker.pkg.dev/linera-io-dev/linera-public-registry/linera`
- Added `--local-build` flag for explicitly building Docker images
locally
   - Made `--remote-image` flag deprecated (remote is now the default)
- Updated image tag logic: uses `latest` for main branch,
`{branch}_release` for other branches
   - Updated help text and examples to reflect the new behavior

2. **`docker/docker-compose.yml`**:
- Updated default `LINERA_IMAGE` from `linera` to
`us-docker.pkg.dev/linera-io-dev/linera-public-registry/linera:latest`
- Applied to all services using the Linera image (proxy, shard,
shard-init)

## Impact

- **Improved UX**: Validators can now deploy without building images
locally
- **Faster deployments**: No need to wait for local builds (which can
take several minutes)
- **Consistency**: All validators use the same official images by
default
- **Backwards compatible**: Users can still build locally using
`--local-build`

## Testing

The script has been tested with:
- Dry run mode to verify image selection logic
- Syntax validation with `bash -n`
- Help output verification

## Related PR

Documentation updates: linera-io/linera-documentation#241

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <[email protected]>

Author: eldios

docker/docker-compose.yml

@@ -46,7 +46,7 @@ services:
         condition: service_completed_successfully
 
   proxy:
-    image: "${LINERA_IMAGE:-linera}"
+    image: "${LINERA_IMAGE:-us-docker.pkg.dev/linera-io-dev/linera-public-registry/linera:latest}"
     container_name: proxy
     ports:
       - "19100:19100"
@@ -60,7 +60,7 @@ services:
         condition: service_completed_successfully
 
   shard:
-    image: "${LINERA_IMAGE:-linera}"
+    image: "${LINERA_IMAGE:-us-docker.pkg.dev/linera-io-dev/linera-public-registry/linera:latest}"
     deploy:
       replicas: 4
     command: ["./compose-server-entrypoint.sh", "scylladb:tcp:scylla:9042", "1"]
@@ -73,7 +73,7 @@ services:
         condition: service_completed_successfully
 
   shard-init:
-    image: "${LINERA_IMAGE:-linera}"
+    image: "${LINERA_IMAGE:-us-docker.pkg.dev/linera-io-dev/linera-public-registry/linera:latest}"
     container_name: shard-init
     command: ["./compose-server-init.sh", "scylladb:tcp:scylla:9042", "1"]
     volumes:

scripts/deploy-validator.sh

@@ -11,7 +11,8 @@
 #   <email>          - Email address for ACME/Let's Encrypt certificates (required)
 #
 # Options:
-#   --remote-image      - Use remote Docker image instead of building locally
+#   --local-build       - Build Docker image locally instead of using registry image
+#   --remote-image      - Explicitly use remote Docker image from registry (deprecated, now default)
 #   --skip-genesis      - Skip downloading genesis configuration
 #   --force-genesis     - Force re-download of genesis configuration
 #   --custom-tag TAG    - Use custom image tag (for testing, no _release suffix)
@@ -120,7 +121,8 @@ ARGUMENTS:
     <email>             Email address for ACME/Let's Encrypt certificates (required)
 
 OPTIONS:
-    --remote-image      Use remote Docker image instead of building locally
+    --local-build       Build Docker image locally instead of using registry image
+    --remote-image      Explicitly use remote Docker image from registry (deprecated, now default)
     --skip-genesis      Skip downloading genesis configuration
     --force-genesis     Force re-download of genesis configuration even if it exists
     --custom-tag TAG    Use custom image tag (for testing, no _release suffix)
@@ -171,20 +173,20 @@ ENVIRONMENT VARIABLES:
                         Default: 4G
 
 EXAMPLES:
-    # Deploy using local build
+    # Deploy using remote image (default behavior)
     $(basename "$0") validator.example.com [email protected]
 
-    # Deploy using remote image with default tag (<branch>_release)
-    $(basename "$0") validator.example.com [email protected] --remote-image
+    # Deploy using local build
+    $(basename "$0") validator.example.com [email protected] --local-build
 
     # Deploy with custom tag for testing (no _release suffix)
-    $(basename "$0") validator.example.com [email protected] --remote-image --custom-tag devnet_2025_08_21
+    $(basename "$0") validator.example.com [email protected] --custom-tag devnet_2025_08_21
 
     # Deploy with fully custom image
     LINERA_IMAGE=my-registry/my-image:my-tag $(basename "$0") validator.example.com [email protected]
 
     # Deploy with custom registry and image name
-    DOCKER_REGISTRY=gcr.io/my-project IMAGE_NAME=custom-linera $(basename "$0") validator.example.com [email protected] --remote-image
+    DOCKER_REGISTRY=gcr.io/my-project IMAGE_NAME=custom-linera $(basename "$0") validator.example.com [email protected]
 
     # Deploy with custom configuration
     NUM_SHARDS=8 $(basename "$0") validator.example.com [email protected]
@@ -203,11 +205,11 @@ EXAMPLES:
 
     # Deploy with custom genesis bucket and path
     GENESIS_BUCKET=https://storage.googleapis.com/my-bucket GENESIS_PATH_PREFIX=my-deployment \
-    $(basename "$0") validator.example.com [email protected] --remote-image
+    $(basename "$0") validator.example.com [email protected]
 
     # Deploy with direct genesis URL override
     GENESIS_URL=https://storage.googleapis.com/linera-io-dev-public/testnet-babbage/genesis.json \
-    $(basename "$0") validator.example.com [email protected] --remote-image
+    $(basename "$0") validator.example.com [email protected]
 
 EOF
 }
@@ -747,6 +749,7 @@ main() {
 	# Parse command line arguments
 	local host=""
 	local email=""
+	local use_local_build=0
 	local use_remote_image=0
 	local skip_genesis=0
 	local force_genesis=0
@@ -762,7 +765,12 @@ main() {
 			usage
 			exit 0
 			;;
+		--local-build)
+			use_local_build=1
+			shift
+			;;
 		--remote-image)
+			# Deprecated option, remote is now default
 			use_remote_image=1
 			shift
 			;;
@@ -936,7 +944,14 @@ main() {
 	if [ -n "${LINERA_IMAGE:-}" ]; then
 		# User provided complete image path, use as-is
 		log INFO "Using user-specified Docker image: ${LINERA_IMAGE}"
-	elif [ ${use_remote_image} -eq 1 ]; then
+	elif [ ${use_local_build} -eq 1 ]; then
+		# Local build explicitly requested
+		export LINERA_IMAGE="${LINERA_IMAGE:-linera}"
+		if ! build_local_image "${git_commit}" "${LINERA_IMAGE}"; then
+			log ERROR "Failed to build local Docker image"
+			exit 1
+		fi
+	else
 		# Construct image path from components
 		local docker_registry="${DOCKER_REGISTRY:-$DEFAULT_DOCKER_REGISTRY}"
 		local image_name="${IMAGE_NAME:-$DEFAULT_IMAGE_NAME}"
@@ -951,19 +966,16 @@ main() {
 			# Environment variable override
 			image_tag="${IMAGE_TAG}"
 		else
-			# Default: branch_name with _release suffix
-			image_tag="${branch_name}_release"
+			# Default: branch_name with _release suffix, or 'latest' for main branch
+			if [ "${branch_name}" = "main" ]; then
+				image_tag="latest"
+			else
+				image_tag="${branch_name}_release"
+			fi
 		fi
 
 		export LINERA_IMAGE="${docker_registry}/${image_name}:${image_tag}"
 		log INFO "Using remote Docker image: ${LINERA_IMAGE}"
-	else
-		# Local build
-		export LINERA_IMAGE="${LINERA_IMAGE:-linera}"
-		if ! build_local_image "${git_commit}" "${LINERA_IMAGE}"; then
-			log ERROR "Failed to build local Docker image"
-			exit 1
-		fi
 	fi
 
 	# Generate genesis URL if not provided