Put a regular user step first.

task/buildkit-rootless-daemonless/0.1/buildkit-rootless-daemonless.yaml

@@ -25,8 +25,8 @@ spec:
     - name: buildkit-cache
       description: For preserving buildkit type=cache mounts between builds.
       optional: true
-      mountPath: /home/user/.local/share/foo
-      # mountPath: /home/user/.local/share/buildkit
+      # mountPath: /home/user/.local/share/foo
+      mountPath: /home/user/.local/share/buildkit
   params:
     - name: OUTPUT
       type: string
@@ -69,6 +69,29 @@ spec:
     - name: metadata-out
       emptyDir: {}
   steps:
+    - name: run-as-user
+      image: $(params.BUILDER_IMAGE)
+      workingDir: "$(workspaces.source.path)"
+      script: |
+        #!/usr/bin/env sh
+        set -euo pipefail
+        echo "yo"
+      securityContext:
+        runAsNonRoot: true
+        runAsUser: 1000
+        runAsGroup: 1000
+    - name: setup-cache-ownership
+      image: $(params.BUILDER_IMAGE)
+      workingDir: "$(workspaces.source.path)"
+      script: |
+        #!/usr/bin/env sh
+        set -euo pipefail
+        chown 1000:1000 /home/user/.local/share/buildkit
+        chmod 0777 /home/user/.local/share/buildkit
+      securityContext:
+        # runAsNonRoot: false
+        runAsUser: 0
+        runAsGroup: 0
     - name: write-config
       image: $(params.BUILDER_IMAGE)
       workingDir: "$(workspaces.source.path)"