[CI] Switch away from kubernetes executor mode (#360)

We are running into reliability problems with the kubernetes executor
mode, hypothesized currently to be due to a complex interaction with
konnectivity-agent pods dying and subsequently killing in-process execs
through the k8s control plane. The plan is to switch back to the
in-container executor mode for now while we sort out the issue upstream
with the konnectivity developers.

This is related to #362.

premerge/linux_runners_values.yaml

@@ -4,17 +4,6 @@ githubConfigSecret: "github-token"
 minRunners: 0
 maxRunners: 4
 
-containerMode:
-  type: "kubernetes"
-  kubernetesModeWorkVolumeClaim:
-    accessModes: ["ReadWriteOnce"]
-    storageClassName: "standard-rwo"
-    resources:
-      requests:
-        storage: "200Gi"
-  kubernetesModeServiceAccount:
-    annotations:
-
 template:
   metadata:
     annotations:
@@ -29,49 +18,28 @@ template:
       premerge-platform: linux
     containers:
     - name: runner
-      image: ghcr.io/actions/actions-runner:latest
-      command: ["/home/runner/run.sh"]
+      image: ghcr.io/llvm/ci-ubuntu-22.04-agent:latest
+      command: ["/home/gha/actions-runner/run.sh"]
       resources:
-        # The container will be scheduled on the same node as this runner.
-        # This means if we don't set the CPU request high-enough here, 2
-        # containers will be scheduled on the same pod, meaning 2 jobs.
+        # If we don't set the CPU request high-enough here, 2 runners might
+        # be scheduled on the same pod, meaning 2 jobs, and they will starve
+        # each other.
         #
         # This number should be:
         #  - greater than number_of_cores / 2:
         #    A value lower than that could allow the scheduler to put 2
-        #    runners in the same pod. Meaning 2 containers in the same pod.
-        #    Meaning 2 jobs sharing the resources.
+        #    runners on the same node. Meaning 2 jobs sharing the resources of
+        #    a single node.
         #  - lower than number_of_cores:
         #    Each pod has some basic services running (metrics for ex). Those
         #    already require some amount of CPU (~0.5). This means we don't
         #    exactly have N cores to allocate, but N - epsilon.
         #
-        # Memory however shall be handled at the container level. The runner
-        # itself doesn't need much, just using something enough not to get
-        # OOM killed.
+        # We also need to request sufficient memory to not get OOM killed.
         requests:
           cpu: 55
-          memory: "8Gi"
+          memory: "200Gi"
         limits:
           cpu: 64
-          memory: "8Gi"
-      env:
-        - name: ACTIONS_RUNNER_CONTAINER_HOOKS
-          value: /home/runner/k8s/index.js
-        - name: ACTIONS_RUNNER_POD_NAME
-          valueFrom:
-            fieldRef:
-              fieldPath: metadata.name
-        - name: ACTIONS_RUNNER_REQUIRE_JOB_CONTAINER
-          value: "true"
-        - name: ACTIONS_RUNNER_CONTAINER_HOOK_TEMPLATE
-          value: "/home/runner/pod-config/linux-container-pod-template.yaml"
-      volumeMounts:
-        - name: container-pod-config
-          mountPath: /home/runner/pod-config
-    securityContext:
-      fsGroup: 123
-    volumes:
-      - name: container-pod-config
-        configMap:
-          name: linux-container-pod-template
+          memory: "256Gi"
+

premerge/main.tf

@@ -199,17 +199,6 @@ resource "kubernetes_secret" "windows_github_pat" {
 }
 
 
-resource "kubernetes_config_map" "linux_container_pod_template" {
-  metadata {
-    name      = "linux-container-pod-template"
-    namespace = "llvm-premerge-linux-runners"
-  }
-
-  data = {
-    "linux-container-pod-template.yaml" : "${file("linux_container_pod_template.yaml")}"
-  }
-}
-
 resource "helm_release" "github_actions_runner_controller" {
   name       = "llvm-premerge-controller"
   namespace  = "llvm-premerge-controller"
@@ -235,9 +224,8 @@ resource "helm_release" "github_actions_runner_set_linux" {
 
   depends_on = [
     kubernetes_namespace.llvm_premerge_linux_runners,
-    kubernetes_config_map.linux_container_pod_template,
-    kubernetes_secret.linux_github_pat,
     helm_release.github_actions_runner_controller
+    kubernetes_secret.linux_github_pat
   ]
 }