[ci] Verify docker contexts

.buildkite/pipelines/pull_request/base.yml

@@ -26,6 +26,18 @@ steps:
         - exit_status: '*'
           limit: 1
 
+  # Move to hourly
+  - command: .buildkite/scripts/steps/docker_context/build.sh
+    label: 'Docker Build Context'
+    agents:
+      queue: n2-4
+    timeout_in_minutes: 30
+    key: build-docker-context
+    retry:
+      automatic:
+        - exit_status: '*'
+          limit: 1
+
   - command: CI_GROUP=Docker .buildkite/scripts/steps/functional/xpack_cigroup.sh
     label: 'Docker CI Group'
     agents:

.buildkite/scripts/steps/docker_context/build.sh

@@ -0,0 +1,15 @@
+#!/bin/bash
+
+set -euo pipefail
+
+echo "--- Create Kibana Docker contexts"
+node scripts/build --skip-initialize --skip-generic-folders --skip-platform-folders --skip-archives
+
+DOCKER_BUILD_FOLDER=$(mktemp)
+
+tar -xf target/kibana-[0-9]*-docker-build-context.tar.gz -C "$DOCKER_BUILD_FOLDER"
+
+cd $DOCKER_BUILD_FOLDER
+
+echo "--- Build default context"
+docker build .