Introduction

The release notes include important installation changes and known issues. They also highlight ways that you can take advantage of new features or enhancements to improve your product usage.

For more information, see the following related resources:

  • Changelog: A full list of changes, including the ability to compare previous patch and minor versions.
  • Upgrade guide: Steps to upgrade from the previous minor version to the current version.
  • Version reference: Information about Solo’s version support.

Breaking changes

Review details about the following breaking changes. To review when breaking changes were released, you can use the comparison feature of the changelog.

Upstream Prometheus upgrade

Gloo Mesh Enterprise includes a built-in Prometheus server to help monitor the health of your Gloo components. This release of Gloo upgrades the Prometheus community Helm chart from version 19.7.2 to 25.11.0. As part of this upgrade, upstream Prometheus changed the selector labels for the deployment, which requires recreating the deployment. To help with this process, the Gloo Helm chart includes a pre-upgrade hook that automatically recreates the Prometheus deployment during a Helm upgrade. This breaking change impacts upgrades from previous versions to version 2.4.10, 2.5.1, or 2.6.0 and later.

If you do not want the redeployment to happen automatically, you can disable this process by setting the prometheus.skipAutoMigration Helm value to true. For example, you might use Argo CD, which converts Helm pre-upgrade hooks to Argo PreSync hooks and causes issues. To ensure that the Prometheus server is deployed with the right version, follow these steps:

  1. Confirm that you have an existing deployment of Prometheus at the old Helm chart version of chart: prometheus-19.7.2.
      kubectl get deploy -n gloo-mesh prometheus-server -o yaml | grep chart
      
  2. Delete the Prometheus deployment. Note that while Prometheus is deleted, you cannot observe Gloo performance metrics.
      kubectl delete deploy -n gloo-mesh prometheus-server
      
  3. In your Helm values file, set the prometheus.skipAutoMigration field to true.
  4. Continue with the Helm upgrade of Gloo Mesh Enterprise. The upgrade recreates the Prometheus server deployment at the new version.

New volume mount for Cilium flow logs

To improve Cilium flog log collection, a new volume cilium-run was introduced and added to the configuration of the Gloo telemetry pipeline. This volume is automatically mounted on the host where the telemetry collectors run when using the default self-signed TLS certificates for the telemetry gateway and collectors. The steps to work around this change depend on your Gloo telemetry pipeline setup:

  • Default self-signed TLS certificates (OpenShift only): When you use the default self-signed TLS certificates for the Gloo telemetry pipeline, the volume is automatically added to the pipeline configuration and mounted on the host during the upgrade. No additional steps are required. However, if you run on OpenShift, elevated permissions for the gloo-mesh service account are required to allow Gloo Mesh Enterprise to mount the volume on the host.

    To elevate the permissions in OpenShift, run the following command on the management cluster and all workload clusters:

      oc adm policy add-scc-to-group hostmount-anyuid system:serviceaccounts:gloo-mesh
      
  • Custom TLS certificates: If you previously configured your telemetry pipeline to use custom TLS certificates, or if you attempt to you use the default Gloo telemetry pipeline settings from a previous release to customize certificate settings in 2.4, you must add the new volume and volume mount to the Gloo agent Helm chart as shown in the following example. For steps on how to set up the Gloo telemetry pipeline with custom certificates, see Set up OTel with a custom certificate.

    1. Required in OpenShift: Elevate the permissions of the gloo-mesh service account to allow mounting of volumes on the host.
        oc adm policy add-scc-to-group hostmount-anyuid system:serviceaccounts:gloo-mesh
        
    2. Add the cilium-run volume mount to the Helm chart for the Gloo agent.
        
      telemetryCollector:
        config:
          exporters:
            otlp:
              # Domain for gateway's DNS entry
              # The default port is 4317.
              # If you set up an external load balancer between the telemetry gateway and collector agents, and you configured TLS passthrough to forward data to the telemetry gateway on port 4317, use port 443 instead.
              endpoint: [domain]:4317
              tls:
                ca_file: /etc/otel-certs/ca.crt
        enabled: true
        resources:
          limits:
            cpu: 2
            memory: 2Gi
          requests:
            cpu: 500m
            memory: 1Gi
        extraVolumes:
          # Include this section if you created a custom root CA cert secret
          - name: root-ca  # customers modify this list entry for BYO SSL certs
            secret:
              # Add your root CA cert secret name
              secretName: telemetry-root-secret
              defaultMode: 420
          - name: telemetry-configmap
            configMap:
              name: gloo-telemetry-collector-config
              items:
                - key: relay
                  path: relay.yaml
          - hostPath:
              path: /var/run/cilium
              type: DirectoryOrCreate
            name: cilium-run
        extraVolumeMounts:
          - name: root-ca  
            readOnly: true
            mountPath: /etc/otel-certs
          - name: telemetry-configmap
            mountPath: /conf
          - name: cilium-run
            mountPath: /var/run/cilium
      telemetryCollectorCustomization:
        # Domain for gateway's DNS entry
        serverName: [domain]
        

Installation changes

In addition to comparing differences across versions in the changelog, review the following installation changes from the previous minor version to version 2.4.

Global workspace during installation

Previously, single cluster installation profiles included a global workspace and workspace settings by default. In version 2.4, you can use the glooMgmtServer.createGlobalWorkspace=true setting in the Helm chart, or create a workspace manually after installation.

OTel collector installation

Previously, to set the endpoint during the OTel collector installation, you might have escaped quotations such as endpoint: "\"${ENDPOINT_TELEMETRY_GATEWAY}\"". Now, the syntax is simplified so that you can enter endpoint: "${ENDPOINT_TELEMETRY_GATEWAY}", such as in the following example.

  
telemetryCollector:
  enabled: true
  config:
    exporters:
      otlp:
        endpoint: "${ENDPOINT_TELEMETRY_GATEWAY}"
  

New features

Review the following new features that are introduced in version 2.4 and that you can enable in your environment.

Redis safe mode

In versions 2.4.11 and lower, a race condition was identified that can be triggered during simultaneous restarts of the management plane and Redis, including an upgrade to a newer Gloo version. If hit, this failure mode can lead to partial translations on the Gloo management server which can result in Istio resources being temporarily deleted from the output snapshots that are sent to the Gloo agents. For more information about this failure scenario, see Redis and Gloo management server restart. To resolve this issue, a new safe mode feature was added that you can enable by setting glooMgmtServer.safeMode Helm chart option to true.

If safe mode is enabled, translation of input snapshots halts until the input snapshots of all registered Gloo agents are present in the Redis cache. This feature improves management plane stability during disaster scenarios and upgrades. For more information, see Safe mode. The safe mode feature is disabled by default.

Redis safe start window

With safe mode, the Gloo management server halts translation until the input snapshots of all workload clusters are present in the Redis cache. However, if clusters have connectivity issues, translation might be halted for a long time, even for healthy clusters. You might want translation to resume after a certain period of time, even if some input snapshots are missing in the Redis cache. To do so, you must use the glooMgmtServer.safeStartWindow field in your Gloo management server Helm values file to specify the time in seconds to halt translation. Note that this setting is ignored if glooMgmtServer.safeMode is set to true. The default value is 180 seconds. You can disable the wait time by setting this field to 0 (zero). For more information, see Option 2: Safe start window.

Break up large Envoy filters

Some Gloo policies, such as JWT or other external auth policies are translated into Envoy filters during the Gloo translation process. These Envoy filters are stored in the Kubernetes data store etcd alongside other Gloo configurations and applied to the ingress gateway or sidecar proxy to enforce the policies. In environments where you apply policies to a lot of apps and routes, the size of the Envoy filter can become very large and exceed the maximum file size limit in etcd. When the maximum file size limit is reached, new configuration is rejected in etcd and Istio, which leads to policies not being applied and enforced properly.

To prevent this issue in your environment, it is recommended to set the new EXPERIMENTAL_SEGMENT_ENVOY_FILTERS_BY_MATCHER environment variable on the Gloo management server to instruct the server to break up large Envoy filters into multiple smaller Envoy filters. In your Helm values file for the Gloo management server, add the following snippet:

  
glooMgmServer: 
  extraEnvs:
    EXPERIMENTAL_SEGMENT_ENVOY_FILTERS_BY_MATCHER:
      value: "true"
  

I/O threads for Redis in 2.4.15

A new Helm value redis.deployment.ioThreads was introduced to specify the number of I/O threads to use for the built-in Redis instance. Redis is mostly single threaded, however some operations, such as UNLINK or slow I/O accesses can be performed on side threads. Increasing the number of side threads can help improve and maximize the performance of Redis as these operations can run in parallel.

If you set I/O threads, the Redis pod must be restarted during the upgrade so that the changes can be applied. During the restart, the input snapshots from all connected Gloo agents are removed from the Redis cache. If you also update settings in the Gloo management server that require the management server pod to restart, the management server’s local memory is cleared and all Gloo agents are disconnected. Although the Gloo agents attempt to reconnect to send their input snapshots and re-populate the Redis cache, some agents might take longer to connect or fail to connect at all. To ensure that the Gloo management server halts translation until the input snapshots of all workload cluster agents are present in Redis, it is recommended to enable safe mode on the management server alongside updating the I/O threads for the Redis pod. For more information, see Safe mode. Note that in version 2.6.0 and later, safe mode is enabled by default.

To update I/O side threads in Redis as part of your Gloo Mesh Enterprise upgrade:

  1. Scale down the number of Gloo management server pods to 0.

      kubectl scale deployment gloo-mesh-mgmt-server --replicas=0 -n gloo-mesh
      
  2. Upgrade Gloo Mesh Enterprise and use the following settings in your Helm values file for the management server. Make sure to also increase the number of CPU cores to one core per thread, and add an additional CPU core for the main Redis thread. The following example also enables safe mode on the Gloo management server to ensure translation is done with the complete context of all workload clusters.

      
    glooMgmtServer:
      safeMode: true
    redis: 
      deployment: 
        ioThreads: 2
        resources: 
          requests: 
            cpu: 3
          limits: 
            cpu: 3
      

Feature changes

Review the following changes that might impact how you use certain features in your Gloo environment.

Sidecar acceleration

Support for the eBPF-based acceleration alpha feature is removed.

Known issues

The Solo team fixes bugs, delivers new features, and makes changes on a regular basis as described in the changelog. Some issues, however, might impact many users for common use cases. These known issues are as follows:

  • Cluster names: Do not use underscores (_) in the names of your clusters or in the kubeconfig context for your clusters.
  • Istio:
    • Due to a lack of support for the Istio CNI and iptables for the Istio proxy, you cannot run Istio (and therefore Gloo Mesh Enterprise) on AWS Fargate. For more information, see the Amazon EKS issue.
      • The WasmDeploymentPolicy Gloo CR is currently unsupported in Istio versions 1.18 and later.
      • For FIPS-compliant Solo distributions of Istio 1.17.2 and 1.16.4, you must use the -patch1 versions of the latest Istio builds published by Solo, such as 1.17.2-patch1-solo-fips for Solo distribution of Istio 1.17. These patch versions fix a FIPS-related issue introduced in the upstream Envoy code. In 1.17.3 and later, FIPS compliance is available in the -fips tags of regular Solo distributions of Istio, such as 1.17.3-solo-fips.
    • OTel pipeline: FIPS-compliant builds are not currently supported for the OTel collector agent image.