Plugin install renders read-only file system error

[olmoser]

Describe the bug
When trying to install a plugin via

apiVersion: grafana.integreatly.org/v1beta1
kind: GrafanaDatasource
metadata:
  name: prometheus
  namespace: grafana
spec:
  instanceSelector:
    matchLabels:
      dashboards: "grafana"
  plugins:
    - name: googlecloud-logging-datasource
      version: 1.2.0

  datasource:
    name: prometheus
    type: prometheus
    access: proxy
    url: http://prometheus-k8s.monitoring.svc:9090
    isDefault: true
    jsonData:
      'tlsSkipVerify': true
      'timeInterval': "10s"
    editable: true

The Pod keeps crashing with the error message

Error: ✗ failed to create temporary file: open /tmp/2140794887.zip: read-only file system

Version
v5.0.0-rc2

To Reproduce
Using the deployment manifest from about will fail the plugin install. However, if you set TMPDIR explicitly as an env var in the Grafana deployment spec, you can work around the error message and the plugin gets installed:

apiVersion: grafana.integreatly.org/v1beta1
kind: Grafana
metadata:
  name: grafana
  namespace: grafana
  labels:
    dashboards: "grafana"
spec:
  deployment:
    spec:
      template:
        spec:
          containers:
            - name: grafana
              env:
                - name: TMPDIR
                  value: /var/lib/grafana

Expected behavior
The plugin gets installed correclty without the need to set the TMPDIR env var.

Runtime (please complete the following information):

• Grafana Operator Version [e.g. v5.0.0]
• Environment: GKE v1.25.7-gke.1000

Additional context
Add any other context about the problem here.

[NissesSenap]

Funny that we haven't gotten this error when trying out some of our other plugins.
Maybe it's something around how the GKE plugin works.

The easiest way forward is probably to just set this value as default for all deployments.
I don't want to remove the read-only filesystem.

[pb82]

This affects other plugins too, just tested with a panel plugin. Setting the TMPDIR sounds like an acceptable solution, it means the plugin gets downloaded and extracted in the same directory, but that should be ok.