feat: Language plugins choose the runner image (#3268)

Language plugins can now declare the runner image to use by including a
ModuleRuntime in the Module schema.
Image names do not include the tag to use, instead FTL will use the same
tag that the rest of FTL is using.
If a language plugin does not choose a runner image, it is defaulted
to`ftl0/ftl-runner`.

---------

Co-authored-by: Alec Thomas <[email protected]>

.github/workflows/ci.yml

@@ -236,15 +236,18 @@ jobs:
       - uses: cashapp/[email protected]
       - uses: ./.github/actions/build-cache
       - run: just build-docker provisioner
-  docker-build-runner:
-    name: Build Runner Docker Image
+  docker-build-runners:
+    name: Build Runner Docker Images
     # if: github.event_name != 'pull_request' || github.event.action == 'enqueued' || contains( github.event.pull_request.labels.*.name, 'run-all')
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v4
       - uses: cashapp/[email protected]
       - uses: ./.github/actions/build-cache
-      - run: just build-docker runner
+      - name: Build Runner Docker Image
+        run: just build-docker runner
+      - name: Build JVM Docker Image
+        run: just build-docker runner-jvm
   docker-build-box:
     name: Build Box Docker Image
     # if: github.event_name != 'pull_request' || github.event.action == 'enqueued' || contains( github.event.pull_request.labels.*.name, 'run-all')

.github/workflows/release.yml

@@ -4,15 +4,15 @@ on:
       - "v[0-9]+.[0-9]+.[0-9]+"
 name: Automatically Build Release
 jobs:
-  build-runner:
-    name: Build Runner Docker Image
+  build-runners:
+    name: Build Runner Docker Images
     runs-on: ubuntu-latest
     steps:
       - name: Checkout code
         uses: actions/checkout@v4
       - name: Init Hermit
         uses: cashapp/[email protected]
-      - name: Build
+      - name: Build Runner
         run: |
           just build-docker runner
           mkdir -p artifacts/ftl-runner
@@ -23,6 +23,17 @@ jobs:
           name: docker-runner-artifact
           path: artifacts/ftl-runner/ftl-runner.tar
           retention-days: 1
+      - name: Build JVM Runner
+        run: |
+          just build-docker runner-jvm
+          mkdir -p artifacts/ftl-runner-jvm
+          docker save -o artifacts/ftl-runner-jvm/ftl-runner-jvm.tar ftl0/ftl-runner-jvm:latest
+      - name: Temporarily save JVM Docker image
+        uses: actions/upload-artifact@v4
+        with:
+          name: docker-runner-jvm-artifact
+          path: artifacts/ftl-runner-jvm/ftl-runner-jvm.tar
+          retention-days: 1
   build-controller:
     name: Build Controller Docker Image
     runs-on: ubuntu-latest
@@ -86,7 +97,7 @@ jobs:
     permissions:
       contents: read
       packages: write
-    needs: [build-runner, build-controller, build-provisioner, build-box]
+    needs: [build-runners, build-controller, build-provisioner, build-box]
     steps:
       - name: Checkout code
         uses: actions/checkout@v4
@@ -99,6 +110,11 @@ jobs:
         with:
           name: docker-runner-artifact
           path: artifacts/ftl-runner
+      - name: Retrieve JVM Runner Docker image
+        uses: actions/download-artifact@v4
+        with:
+          name: docker-runner-jvm-artifact
+          path: artifacts/ftl-runner-jvm
       - name: Retrieve Controller Docker image
         uses: actions/download-artifact@v4
         with:
@@ -116,6 +132,8 @@ jobs:
           path: artifacts/ftl-box
       - name: Load Runner Docker image
         run: docker load -i artifacts/ftl-runner/ftl-runner.tar
+      - name: Load JVM Runner Docker image
+        run: docker load -i artifacts/ftl-runner-jvm/ftl-runner-jvm.tar
       - name: Load Controller Docker image
         run: docker load -i artifacts/ftl-controller/ftl-controller.tar
       - name: Load Provisioner Docker image
@@ -133,6 +151,9 @@ jobs:
           docker tag ftl0/ftl-runner:latest ftl0/ftl-runner:"$GITHUB_SHA"
           docker tag ftl0/ftl-runner:latest ftl0/ftl-runner:"$version"
           docker push -a ftl0/ftl-runner
+          docker tag ftl0/ftl-runner-jvm:latest ftl0/ftl-runner-jvm:"$GITHUB_SHA"
+          docker tag ftl0/ftl-runner-jvm:latest ftl0/ftl-runner-jvm:"$version"
+          docker push -a ftl0/ftl-runner-jvm
           docker tag ftl0/ftl-controller:latest ftl0/ftl-controller:"$GITHUB_SHA"
           docker tag ftl0/ftl-controller:latest ftl0/ftl-controller:"$version"
           docker push -a ftl0/ftl-controller

Dockerfile.runner

@@ -6,9 +6,7 @@ RUN apt-get install -y curl git zip
 COPY ./bin /src/bin
 ENV PATH="/src/bin:$PATH"
 ENV HERMIT_STATE_DIR=/hermit
-RUN hermit install openjdk-17.0.8_7
 RUN go version
-RUN mvn -B --version
 
 WORKDIR /src
 
@@ -32,9 +30,6 @@ RUN apt-get install -y ca-certificates
 
 WORKDIR /root/
 
-ENV PATH="/root/jdk/bin:$PATH"
-ENV JAVA_HOME="/root/jdk"
-COPY --from=builder /hermit/pkg/openjdk-17.0.8_7/ /root/jdk/
 COPY --from=builder /src/build/release/ftl-runner .
 COPY --from=builder /src/build/release/ftl .
 RUN mkdir deployments

Dockerfile.runner-jvm

@@ -0,0 +1,19 @@
+FROM ubuntu:24.04 AS builder
+RUN apt-get update
+RUN apt-get install -y curl git zip
+
+# Seed some of the most common tools - this will be cached
+COPY ./bin /src/bin
+ENV PATH="/src/bin:$PATH"
+ENV HERMIT_STATE_DIR=/hermit
+RUN hermit install openjdk-17.0.8_7
+RUN mvn -B --version
+
+# Finally create the runtime image.
+FROM ftl0/ftl-runner:latest
+
+WORKDIR /root/
+
+ENV PATH="/root/jdk/bin:$PATH"
+ENV JAVA_HOME="/root/jdk"
+COPY --from=builder /hermit/pkg/openjdk-17.0.8_7/ /root/jdk/

backend/controller/controller.go

@@ -1585,11 +1585,13 @@ func (s *Service) watchModuleChanges(ctx context.Context, sendChange func(respon
 				delete(moduleByDeploymentKey, deletion.String())
 			} else if message, ok := notification.Message.Get(); ok {
 				moduleSchema := message.Schema.ToProto().(*schemapb.Module) //nolint:forcetypeassert
-				moduleSchema.Runtime = &schemapb.ModuleRuntime{
-					Language:    message.Language,
-					CreateTime:  timestamppb.New(message.CreatedAt),
-					MinReplicas: int32(message.MinReplicas),
+				if moduleSchema.Runtime == nil {
+					moduleSchema.Runtime = &schemapb.ModuleRuntime{
+						Language: message.Language,
+					}
 				}
+				moduleSchema.Runtime.CreateTime = timestamppb.New(message.CreatedAt)
+				moduleSchema.Runtime.MinReplicas = int32(message.MinReplicas)
 
 				hasher := sha.New()
 				data := []byte(moduleSchema.String())

backend/controller/scaling/k8sscaling/deployment_provisioner.go

@@ -266,7 +266,24 @@ func (r *DeploymentProvisioner) handleNewDeployment(ctx context.Context, dep *sc
 	if err != nil {
 		return err
 	}
-	runnerImage := strings.ReplaceAll(ourImage, "controller", "runner")
+
+	// runner images use the same tag as the controller
+	rawRunnerImage := optional.Ptr(dep.Runtime.Image).Default("ftl0/ftl-runner")
+	var runnerImage string
+	if len(strings.Split(rawRunnerImage, ":")) != 1 {
+		return fmt.Errorf("module runtime's image should not contain a tag: %s", rawRunnerImage)
+	}
+	if strings.HasPrefix(rawRunnerImage, "ftl0/") {
+		// Images in the ftl0 namespace should use the same tag as the controller and use the same namespace as ourImage
+		runnerImage = strings.ReplaceAll(ourImage, "ftl-controller", rawRunnerImage[len(`ftl0/`):])
+	} else {
+		// Images outside of the ftl0 namespace should use the same tag as the controller
+		ourImageComponents := strings.Split(ourImage, ":")
+		if len(ourImageComponents) != 2 {
+			return fmt.Errorf("expected <name>:<tag> for image name %q", ourImage)
+		}
+		runnerImage = rawRunnerImage + ":" + ourImageComponents[1]
+	}
 
 	deployment.Name = name
 	deployment.OwnerReferences = []v1.OwnerReference{{APIVersion: "v1", Kind: "service", Name: name, UID: service.UID}}