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  1. OpenShift Bugs
  2. OCPBUGS-23516

Monitoring console plugin should avoid browser-caching failures


    • Icon: Bug Bug
    • Resolution: Done-Errata
    • Icon: Major Major
    • 4.15.0
    • 4.15
    • Monitoring
    • None
    • Important
    • No
    • Approved
    • False
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    • NA
    • Release Note Not Required
    • In Progress
    • Customer Escalated

      Description of problem:

      MON-2967 and cmo#1890 moved the Observe console menu into a console plugin (in 4.15? 4.14?). Sometimes If-Modified-Since browser caching results in failures that result in a missing Observe menu, and when the user eventually finds /k8s/cluster/operator.openshift.io~v1~Console/cluster/console-plugins, render failure as:

      Failed to get a valid plugin manifest from /api/plugins/monitoring-plugin/
      SyntaxError: Unexpected end of JSON input

      This appears to be the result of the browser's If-Modified-Since caching:

      $ curl -sH Accept:application/json -H Cache-Control:max-age=0 -H 'Cookie: openshift-session-token=...; login-state=...; ...; csrf-token=...'
      -H 'If-Modified-Since: Fri, 03 Nov 2023 00:47:45 GMT' -i https://console.build02.ci.openshift.org/api/plugins/monitoring-plugin/plugin-manifest.json
      HTTP/1.1 200 OK
      date: Tue, 21 Nov 2023 16:52:55 GMT
      etag: "65444331-9a2"
      last-modified: Fri, 03 Nov 2023 00:47:45 GMT
      referrer-policy: strict-origin-when-cross-origin
      server: nginx/1.20.1
      x-content-type-options: nosniff
      x-dns-prefetch-control: off
      x-frame-options: DENY
      x-xss-protection: 1; mode=block
      content-length: 0

      While a more recent If-Modified-Since returns populated JSON:

      $ curl -sH Accept:application/json -H 'If-Modified-Since: Fri, 10 Nov 2023 10:47:45 GMT' -H 'Cookie: openshift-session-token=...; login-state=...; ...; csrf-token=...' https://console.build02.ci.openshift.org/api/plugins/monitoring-plugin/plugin-manifest.json | jq . | head
        "name": "monitoring-plugin",
        "version": "1.0.0",
        "displayName": "OpenShift console monitoring plugin",
        "description": "This plugin adds the monitoring UI to the OpenShift web console",
        "dependencies": {
          "@console/pluginAPI": "*"
        "extensions": [

      Disabling caching on the monitoring-plugin side would avoid this issues. But fixing 304 handling in the console's proxy would likely also resolve the issue.

      Version-Release number of selected component (if applicable):

      Seen in 4.15.0-ec.2. Reproduced in ec.2. Failed to reproduce in ec.1. Possibly a regression from ec.1 to ec.2, although I haven't identified a regressing commit yet.

      How reproducible:

      Seen multiple times by multiple users in 4.15.0-ec.2 in two long-lived clusters, and also reproduced in an ec.2 Cluster Bot cluster. Likely consistently reprodible on ec.2.

      Steps to Reproduce:

      1. Install a cluster, e.g. with launch 4.15.0-ec.2 gcp.
      2. Log into the console and use the developer tab to get an openshift-session-token value from a successful HTTPS request.

      $ curl -ksi -H "Cookie: openshift-session-token=${TOKEN}" "https://${HOST}/api/plugins/monitoring-plugin/plugin-manifest.json" | grep 'HTTP\|content-\|last-modified'

      with your ${TOKEN} and ${HOST}, to confirm 200 responses and find the last-modified value.

      $ curl -ksi -H "If-Modified-Since: ${LAST_MODIFIED}" -H "Cookie: openshift-session-token=${TOKEN}" "https://${HOST}/api/plugins/monitoring-plugin/plugin-manifest.json"

      with your ${TOKEN}, ${HOST}, and ${LAST_MODIFIED}.

      Actual results:

      Observe menu is missing, with browser-console logs like:

      Failed to get a valid plugin manifest from /api/plugins/monitoring-plugin/
      SyntaxError: Unexpected end of JSON input

      200 responses with no content when If-Modified-Since is greater than or equal to the content's last-modified.

      Expected results:

      Reliably successful loading of the monitoring console plugin, with a 304 when If-Modified-Since is greater than or equal to the content's last-modified.

      Possibly more obvious warnings pointing at /k8s/cluster/operator.openshift.io~v1~Console/cluster/console-plugins when plugins fail to load.

      Additional info:

      Using the browser's development tools to disable caching while loading the console avoids the problematic caching interaction.

            spasquie@redhat.com Simon Pasquier
            trking W. Trevor King
            Tai Gao Tai Gao
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            36 Start watching this issue