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What's new in Kubernetes 1.21

What's new in Kubernetes 1.21

Presented in the CNCF Webinar series

Nabarun Pal

May 20, 2021
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  1. What’s New in Kubernetes 1.21

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  2. © 2020 Cloud Native Computing Foundation
    2
    Anna Jung
    1.21 Enhancements Lead
    @antheajung
    Presenters
    Divya Mohan
    1.21 Communications
    Lead & Moderator
    @Divya_Mohan02
    Nabarun Pal
    1.21 Release Lead
    @theonlynabarun

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  3. © 2020 Cloud Native Computing Foundation
    3
    Agenda
    ★ 1.22 Release Updates
    ★ 1.21 Highlights
    ★ SIG Updates
    ★ Q&A

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  4. 1.22 Release Updates

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  5. © 2020 Cloud Native Computing Foundation
    5
    Overview
    ★ 1.22 Release Timeline
    ○ Start Date: 26th of April 2021
    ■ Enhancements Freeze: 13th of May 2021 23:59 PDT
    ■ Code Freeze: 8th of July 2021 18:00 PDT
    ○ Target Release Date: 4th of August 2021
    ★ Kubernetes Release Cadence has changed to 3 releases
    per year
    ○ Roughly one Minor release every 4 months
    ○ Enhance determinism and reduce risk

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  6. 1.21 Highlights

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  7. © 2020 Cloud Native Computing Foundation
    7
    Kubernetes 1.21 - Power to the Community
    Logo Credits: Aravind Sekar / Behance

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  8. © 2020 Cloud Native Computing Foundation
    8
    Overview
    ★ 51 total enhancements tracked in 1.21
    ○ 13 Stable Enhancements
    ○ 15 Graduating to Beta
    ○ 21 Introduced Alpha features
    ○ 2 Deprecations

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  9. © 2020 Cloud Native Computing Foundation
    9
    ★ CronJobs graduate to Stable
    ★ Immutable Secrets and ConfigMaps to Stable
    ★ IPv4/IPv6 dual-stack support
    ★ Graceful Node Shutdown
    Major Themes!

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  10. © 2020 Cloud Native Computing Foundation
    10
    ★ PersistentVolume Health Monitor
    ★ Reducing Kubernetes Build Maintenance
    ★ PodSecurityPolicy Deprecation
    ★ TopologyKey Deprecation
    (more) Major Themes!

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  11. API MACHINERY

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  12. © 2020 Cloud Native Computing Foundation
    13
    Efficient watch resumption after kube-apiserver reboot
    ● Avoid tons of relists during kube-apiservers
    rolling upgrades
    ● Avoid different instances of
    kube-apiserver stuck with watchcache
    synced to different resource versions for
    extended period of time
    Tracking Issue
    Enhancement Proposal
    Status: Stable
    Status: Beta

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  13. © 2020 Cloud Native Computing Foundation
    14
    Apply for client-go's typed clients
    • Introduces a type-safe programmatic
    way to call server side apply from
    client-go
    • Client-go bundles a set of Apply
    configurations
    • Clears the path for server side apply to go
    GA
    Tracking Issue
    Enhancement Proposal
    Status: Beta

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  14. © 2020 Cloud Native Computing Foundation
    15
    Immutable label selectors for all namespaces
    • Introduces a reserved label
    “kubernetes.io/metadata.name” which
    will be set to name of the namespace
    • Adds the ability to select namespaces by
    name reliably using traditional label
    selector methods.
    Tracking Issue
    Enhancement Proposal
    Status: Beta

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  15. © 2020 Cloud Native Computing Foundation
    17
    CronJobs graduate to Stable
    ● CronJobs graduated to Beta in
    Kubernetes 1.21
    ● The old controllers and feature flags have
    been removed Tracking Issue
    Enhancement Proposal
    Status: Beta
    Status: Stable

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  16. © 2020 Cloud Native Computing Foundation
    18
    Graduate PodDisruptionBudget (PDB) to stable
    ● Makes PDBs mutable
    ● Address performance issues in the PDB
    Controller
    Tracking Issue
    Enhancement Proposal
    Status: Beta
    Status: Stable

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  17. © 2020 Cloud Native Computing Foundation
    19
    TTL After Finished Controller
    ● Finished resources like `Jobs` and `Pods`
    can accumulate in a cluster over time if
    they are not cleaned periodically
    ● Make it easy to for the users to specify a
    time-based clean up mechanism for
    them
    Tracking Issue
    Enhancement Proposal
    Status: Stable
    Status: Beta

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  18. © 2020 Cloud Native Computing Foundation
    20
    Random Pod Selection on ReplicaSet Downscale
    ● Implements a randomized algorithm to
    choose Pods to be killed on a ReplicaSet
    downscale event
    ● Also keeps into consideration the existing
    heuristics Tracking Issue
    Enhancement Proposal
    Status: Beta
    Status: Alpha

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  19. © 2020 Cloud Native Computing Foundation
    21
    Indexed Job
    ● Provides users with support to run massively
    parallel programs
    ● The Pods running can talk to each other with
    the addition of a Headless Service
    Tracking Issue
    Enhancement Proposal
    Status: Beta
    Status: Alpha

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  20. © 2020 Cloud Native Computing Foundation
    22
    Suspend Jobs
    ● Adds a `suspend` boolean field to Job
    specification
    ● It allows to suspend and resume jobs
    ● Useful for preserving existing Job
    metadata like successful or failed
    completions
    Tracking Issue
    Enhancement Proposal
    Status: Stable
    Status: Alpha

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  21. © 2020 Cloud Native Computing Foundation
    23
    ReplicaSet Pod Deletion Cost
    ● Influence the order of Pod deletion on
    downscale events
    ● `controller.kubernetes.io/pod-deletion-cost`
    can be provided as an annotation
    ● Pods with Lower pod deletion cost will be
    deleted first
    Tracking Issue
    Enhancement Proposal
    Status: Stable
    Status: Alpha

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  22. © 2020 Cloud Native Computing Foundation
    25
    Pod Security Policy
    ● Deprecation starts in 1.21
    ● Planned to be removed in 1.25
    ● Replacement being worked on Tracking Issue
    Enhancement Proposal
    Status: Deprecated
    Deprecation Blog

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  23. © 2020 Cloud Native Computing Foundation
    26
    External client-go credential providers
    ● Allow out-of-tree implementation
    credential providers in client-go
    ● Ensure that credentials can be rotated
    without restarting clients
    ● Eventually make client-go vendor neutral
    by deprecating `gcp` and `azure`
    authentication options
    Tracking Issue
    Enhancement Proposal
    Status: Stable
    Status: Beta

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  24. © 2020 Cloud Native Computing Foundation
    27
    Bound Service Account Tokens: separate RootCAConfigMap
    from BoundServiceAccountTokenVolume
    ● Audience of issued JWTs would be bound
    ● Auto-configured service account tokens in
    pods use projected tokens
    Tracking Issue
    Enhancement Proposal
    Status: Stable
    Status: Beta

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  25. © 2020 Cloud Native Computing Foundation
    28
    Bound Service Account Tokens: RootCAConfigMap to GA
    ● Publishes a `kube-root-ca.crt` ConfigMap to
    every namespace
    ● This ConfigMap contains a CA bundle used for
    verifying connections to the kube-apiserver Tracking Issue
    Enhancement Proposal
    Status: Stable

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  26. © 2020 Cloud Native Computing Foundation
    29
    Service Account signing key retrieval
    ● Allow authorized systems to discover the
    information they need to authenticate
    Kubernetes Service Account tokens
    ● Eventual goal is to make the Kubernetes API
    Server OIDC compatible
    Tracking Issue
    Enhancement Proposal
    Status: Stable

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  27. © 2020 Cloud Native Computing Foundation
    31
    Include kubectl command metadata in http request headers
    Allows cluster admins to use this information for
    telemetry and debugging
    Tracking Issue
    Enhancement Proposal
    Status: Stable
    Status: Alpha

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  28. © 2020 Cloud Native Computing Foundation
    32
    Default container behavior
    Kubectl commands can consume this information
    to decide the container to operate on
    Tracking Issue
    Enhancement Proposal
    Status: Stable
    Status: Alpha

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  29. Cloud Provider

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  30. © 2020 Cloud Native Computing Foundation
    34
    Leader Migration for Controller Managers
    ● Enables HA migration of in-tree to out-of-tree
    cloud providers
    ● Defines a set of guidelines and processes Tracking Issue
    Enhancement Proposal
    Status: Stable
    Status: Alpha

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  31. INSTRUMENTATION

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  32. © 2020 Cloud Native Computing Foundation
    36
    Metrics Stability Enhancement
    ● Deprecation lifecycle is in place
    to better handle deprecation of
    stable metrics
    ● Deprecation notice in the
    description text (Deprecated from
    x.y) and a warning log
    Tracking Issue
    Enhancement Proposal
    Status: Stable

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  33. © 2020 Cloud Native Computing Foundation
    37
    Structured logging
    ● Structured logging available for
    Kubelet
    Tracking Issue
    Enhancement Proposal
    Status: Alpha

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  34. © 2020 Cloud Native Computing Foundation
    38
    Expose metrics about resource requests and limits
    that represent the pod model
    ● The `kube-scheduler` exposes
    optional metrics that reports the
    requested resources and the
    desired limits of all running pods Tracking Issue
    Enhancement Proposal
    Status: Beta

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  35. © 2020 Cloud Native Computing Foundation
    39
    Defend against logging secrets via static analysis
    ● Static analysis to be used during
    testing to prevent various types of
    sensitive information from leaking
    via logs Tracking Issue
    Enhancement Proposal
    Status: Beta

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  36. © 2020 Cloud Native Computing Foundation
    40
    Metric cardinality enforcement
    ● Turn off metrics to mitigate issue
    where metrics causes memory
    leaks
    ● Turn off metrics using
    `--disabled-metrics`
    ● Set allow-list of label value for
    metrics using `--allow-label-value`
    Status: Alpha
    Tracking Issue
    Enhancement Proposal

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  37. © 2020 Cloud Native Computing Foundation
    42
    Add IPv4/IPv6 dual-stack support
    ● Dual stack mode to support
    assigning both IPv4 and IPv6
    enabled by default Tracking Issue
    Enhancement Proposal
    Status: Beta

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  38. © 2020 Cloud Native Computing Foundation
    43
    EndpointSlice API
    ● In the v1 API, `topology` field was
    removed in favor of the
    dedicated fields `nodeName`
    and `zone`
    ● The Endpoints controller adds
    annotation to indicate over
    capacity for an Endpoints
    resource with more than 1000
    endpoints
    Tracking Issue
    Enhancement Proposal
    Status: Stable

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  39. © 2020 Cloud Native Computing Foundation
    44
    Service Type=LoadBalancer Class
    ● Option to specify the class of a
    load balancer implementation for
    `LoadBalancer` type of Service
    ● Introduces field
    `service.spec.loadBalancerClass`
    in Service
    Status: Alpha
    Tracking Issue
    Enhancement Proposal

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  40. © 2020 Cloud Native Computing Foundation
    45
    NetworkPolicy port range
    ● Option to enable
    `NetworkPolicyEndpoint` to target
    a range of ports instead of a
    single port when setting a network
    policy
    ● Introduces field `endPort` in
    NetworkPolicy
    Status: Alpha
    Tracking Issue
    Enhancement Proposal

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  41. © 2020 Cloud Native Computing Foundation
    46
    Service Internal Traffic Policy
    ● Introduce a new field
    `spec.internalTrafficPolicy` in
    Service that kube-proxy uses to
    filter the endpoint it routes
    ● When set to `Cluster` or missing, all
    endpoints are considered
    ● When set to `Local`, only node
    local endpoints are considered
    Status: Alpha
    Tracking Issue
    Enhancement Proposal

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  42. © 2020 Cloud Native Computing Foundation
    47
    Block service ExternalIPs via admission
    ● Allow users to disable the
    `externalIPs` feature of Services
    via `DenyServiceExternalIPs`
    admission control
    ● Blocks deployment of any
    resource that uses `externalIPs`
    field
    Tracking Issue
    Enhancement Proposal
    Status: Stable

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  43. © 2020 Cloud Native Computing Foundation
    48
    Namespace Scoped Ingress Class Parameters
    ● IngressClass parameters are
    Namespace scoped resources
    Status: Alpha
    Tracking Issue
    Enhancement Proposal

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  44. © 2020 Cloud Native Computing Foundation
    49
    Topology Aware Hints
    ● Provide hints to Cluster
    components like kube-proxy to
    influence how traffic to is routed
    by keeping traffic within the zone
    it originated from
    ● Activate feature by setting
    annotation
    `service.kubernetes.io/topology-a
    ware-hints` to `auto`
    Status: Alpha
    Tracking Issue
    Enhancement Proposal

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  45. © 2020 Cloud Native Computing Foundation
    50
    Topology aware routing of services
    ● Alpha topologyKeys API is now
    deprecated in favor of topology
    aware hints
    Status: Deprecated
    Tracking Issue
    Enhancement Proposal

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  46. © 2020 Cloud Native Computing Foundation
    52
    Add sysctl support
    ● Support for Linux sysctl interface to
    tune OS parameters for deployed
    Pods
    ● Beta since 1.11, now stable Tracking Issue
    Enhancement Proposal
    Status: Stable

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  47. © 2020 Cloud Native Computing Foundation
    53
    Provide RunAsGroup feature for Containers in a
    Pod
    ● Support `runAsGroup` field inside
    the `securityContext` field in a
    Pod
    ● Beta since 1.14, now stable Tracking Issue
    Enhancement Proposal
    Status: Stable

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  48. © 2020 Cloud Native Computing Foundation
    54
    Memory Manager
    ● New component in Kubelet
    ecosystem to guarantee memory
    allocation for pods in the
    Guaranteed QoS class
    ● single-NUMA and multi-NUMA
    allocation strategies
    Status: Alpha
    Tracking Issue
    Enhancement Proposal

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  49. © 2020 Cloud Native Computing Foundation
    55
    Graceful node shutdown
    ● `GracefulNodeShutdown`
    enabled by default
    ● Kubelet detects node system
    shutdown and gracefully
    terminates pods running on the
    node
    Tracking Issue
    Enhancement Proposal
    Status: Beta

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  50. © 2020 Cloud Native Computing Foundation
    56
    Add downward API support for hugepages
    ● Pods are able to fetch information
    on their hugepage requests and
    limits via the downward API
    ● Supported if all workers in the
    cluster are min 1.20 version
    Tracking Issue
    Enhancement Proposal
    Status: Beta

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  51. © 2020 Cloud Native Computing Foundation
    57
    Remove cAdvisor json metrics from the Kubelet
    ● Deprecated since 1.18
    ● Removed permanently
    Tracking Issue
    Enhancement Proposal
    Status: Stable

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  52. © 2020 Cloud Native Computing Foundation
    58
    Add configurable grace period to probes
    ● Introduce probe-level
    `terminationGracePeriodSeconds`
    ● Override the pod-level
    `terminationGracePeriodSeconds`
    for liveness or startup termination,
    and will be ignored for readiness
    probes
    Status: Alpha
    Tracking Issue
    Enhancement Proposal

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  53. © 2020 Cloud Native Computing Foundation
    59
    Extend podresources API to report allocatable
    resources
    ● Addition to Kubelet pod resources
    endpoint to allow third party
    consumers to learn about the
    compute resources allocated to a
    Pod
    ● Introduces
    `GetAllocatableResources`
    endpoint
    Status: Alpha
    Tracking Issue
    Enhancement Proposal

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  54. © 2020 Cloud Native Computing Foundation
    60
    CRIContainerLogRotation
    ● Enables container log rotation for
    Container Runtime Interface (CRI)
    container runtime
    ● Beta since 1.11, now stable Tracking Issue
    Enhancement Proposal
    Status: Stable

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  55. © 2020 Cloud Native Computing Foundation
    62
    Honor Nominated node during the new scheduling
    cycle
    ● Define a preferred node to speed
    up scheduling
    ● Introduce a new field
    `.status.nomindatedNodeName`
    in Pod Tracking Issue
    Enhancement Proposal
    Status: Alpha

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  56. © 2020 Cloud Native Computing Foundation
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    Namespace selector for pod affinity
    ● Introduces `namespaceSelector`
    to allow setting namespaces
    dynamically for affinity term
    ● Introduces
    `CrossNamespacePodAffinity`
    that limits which namespaces are
    allows to have pods with affinity
    terms that cross namespaces
    Tracking Issue
    Enhancement Proposal
    Status: Alpha

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  57. © 2020 Cloud Native Computing Foundation
    65
    Immutable Secrets and ConfigMaps
    ● Protects against inadvertent updates to
    Secrets and ConfigMaps
    ● Kubelet doesn’t poll for such Secrets and
    ConfigMaps resulting in performance
    improvements Tracking Issue
    Enhancement Proposal
    Status: Beta
    Status: Stable

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  58. © 2020 Cloud Native Computing Foundation
    66
    Persistent Volume Health Monitor
    • Improves UX of handling underlying
    storage issues in PersistentVolumes
    • Early signal for impending storage failure
    events preventing serious problems Tracking Issue
    Enhancement Proposal
    Status: Beta
    Status: Alpha

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  59. © 2020 Cloud Native Computing Foundation
    67
    Storage Capacity Constraints for Pod Scheduling
    • Prevents Pod creation getting stuck due
    to unavailability of requested storage
    • Schedule pods to nodes where the
    requested storage capacity is available Tracking Issue
    Enhancement Proposal
    Status: Beta

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  60. © 2020 Cloud Native Computing Foundation
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    Generic Ephemeral Inline Volumes
    ● Extend Kubernetes with CSI drivers that
    provide light-weight, local volumes
    ● New volume source, the so-called
    EphemeralVolumeSource contains all
    fields that are needed to create a
    volume claim
    ● The Pod is the owner of the volume claim,
    if the pod gets deleted the garbage
    collector deletes also the volume
    Status: Alpha
    Tracking Issue
    Enhancement Proposal
    Status: Beta

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  61. © 2020 Cloud Native Computing Foundation
    69
    Prioritizing nodes based on volume capacity
    ● Optimize Volume resource usage
    ● Schedules pods on nodes where the
    available capacity is close to requested
    capacity
    Status: Alpha
    Tracking Issue
    Enhancement Proposal

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  62. © 2020 Cloud Native Computing Foundation
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    Azure file in-tree to CSI driver migration
    If you have the Azure File CSI
    Driver, you can turn on the feature
    gate CSIMigrationAzureFile to
    enable the same
    Status: Alpha
    Tracking Issue
    Enhancement Proposal
    Status: Beta

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  63. © 2020 Cloud Native Computing Foundation
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    Service Account Token for CSI Driver
    • Allow CSI driver to request
    audience-bounded service account
    tokens of pods from kubelet to
    NodePublishVolume.
    • Provide an option to re-execute
    NodePublishVolume in a best-effort
    manner.
    Status: Alpha
    Tracking Issue
    Enhancement Proposal
    Status: Beta

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  64. © 2020 Cloud Native Computing Foundation
    73
    Reducing Kubernetes Build Maintenance
    ● The project used to maintain multiple
    build systems
    ● CI processes using Bazel moved to `make
    build`
    ● Bazel based build and related tooling are
    removed Tracking Issue
    Enhancement Proposal
    Status: Stable

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  65. Release Team Shadow Program

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  66. © 2020 Cloud Native Computing Foundation
    75
    Release Team Shadow Program
    ★ Release Team Roles
    ○ Release Team Lead
    ○ Enhancements
    ○ CI Signal
    ○ Bug Triage
    ○ Docs
    ○ Release Notes
    ○ Communications
    ★ 1 lead : 3 - 5 shadows
    ★ ~4 months // weekly workload varies depending on team
    ★ Release Team Shadows Github repo

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