fix: isolate usercode container

Dockerfile

@@ -1,8 +1,8 @@
-FROM python:3.12-slim
+# ── Usercode: full application (gRPC server) ─────────────────────────
+FROM python:3.12-slim AS usercode
 
 WORKDIR /app
 
-# Install uv
 COPY --from=ghcr.io/astral-sh/uv:latest /uv /usr/local/bin/uv
 
 # Install dependencies before copying full source (layer caching)
@@ -12,9 +12,23 @@ RUN uv sync --frozen --no-dev 2>/dev/null || uv sync --no-dev
 # Copy application source
 COPY . .
 
-# Make the venv's binaries available on PATH
 ENV PATH="/app/.venv/bin:$PATH"
 ENV DAGSTER_HOME=/app/dagster_home
 
 RUN chmod +x /app/entrypoint.sh
 ENTRYPOINT ["/app/entrypoint.sh"]
+
+# ── Infrastructure: webserver / daemon (no user code) ────────────────
+FROM python:3.12-slim AS dagster-infra
+
+WORKDIR /app
+
+COPY --from=ghcr.io/astral-sh/uv:latest /uv /usr/local/bin/uv
+
+# Only the Dagster packages needed to run webserver / daemon and reach
+# the metadata store.  No application code is installed.
+RUN uv pip install --system dagster dagster-webserver dagster-postgres
+
+COPY dagster_home/ ./dagster_home/
+
+ENV DAGSTER_HOME=/app/dagster_home

docker-compose.yaml

@@ -1,10 +1,5 @@
-version: "3.9"
-
 # Shared config for all dagster services
 x-dagster: &dagster-common
-  build:
-    context: .
-    dockerfile: Dockerfile
   env_file: .env
   environment:
     DAGSTER_HOME: /app/dagster_home
@@ -37,34 +32,49 @@ services:
   # User code gRPC server
   dagster-usercode:
     <<: *dagster-common
+    build:
+      context: .
+      target: usercode
     container_name: dagster-usercode
-    command: ["dagster", "api", "grpc", "-h", "0.0.0.0", "-p", "4000", "-m", "data_platform"]
+    command:
+      ["dagster", "api", "grpc", "-h", "0.0.0.0", "-p", "4000", "-m", "data_platform.definitions"]
     volumes:
       - dbt-target:/app/dbt/target
     expose:
       - "4000"
+    healthcheck:
+      test: ["CMD", "dagster", "api", "grpc-health-check", "-p", "4000"]
+      interval: 15s
+      timeout: 10s
+      retries: 5
+      start_period: 30s
 
   # Web UI
   dagster-webserver:
     <<: *dagster-common
+    build:
+      context: .
+      target: dagster-infra
     container_name: dagster-webserver
-    entrypoint: []
-    command: ["dagster-webserver", "-h", "0.0.0.0", "-p", "3000"]
+    command:
+      ["dagster-webserver", "-h", "0.0.0.0", "-p", "3000", "-w", "/app/dagster_home/workspace.yaml"]
     ports:
       - "3000:3000"
     depends_on:
       dagster-usercode:
-        condition: service_started
+        condition: service_healthy
 
   # Schedules, sensors and run queuing
   dagster-daemon:
     <<: *dagster-common
+    build:
+      context: .
+      target: dagster-infra
     container_name: dagster-daemon
-    entrypoint: []
-    command: ["dagster-daemon", "run"]
+    command: ["dagster-daemon", "run", "-w", "/app/dagster_home/workspace.yaml"]
     depends_on:
       dagster-usercode:
-        condition: service_started
+        condition: service_healthy
 
 volumes:
   postgres-data:

pyproject.toml

@@ -20,7 +20,7 @@ build-backend = "hatchling.build"
 packages = ["data_platform"]
 
 [tool.dagster]
-module_name = "data_platform"
+module_name = "data_platform.definitions"
 attribute = "defs"
 
 [dependency-groups]