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An alpha implementation of the the TLS bootstrap API described in docs/proposals/kubelet-tls-bootstrap.md. (#25562, @gtank)
Action Required
[kubelet] Allow opting out of automatic cloud provider detection in kubelet. By default kubelet will auto-detect cloud providers (#28258, @vishh)
If you use one of the kube-dns replication controller manifest in cluster/saltbase/salt/kube-dns, i.e. cluster/saltbase/salt/kube-dns/{skydns-rc.yaml.base,skydns-rc.yaml.in}, either substitute one of __PILLAR__FEDERATIONS__DOMAIN__MAP__ or {{ pillar['federations_domain_map'] }} with the corresponding federation name to domain name value or remove them if you do not support cluster federation at this time. If you plan to substitute the parameter with its value, here is an example for {{ pillar['federations_domain_map'] } (#28132, @madhusudancs)
Adding loadBalancer services and nodeports services to quota system
Known Issues and Important Steps before Upgrading
The following versions of Docker Engine are supported - v1.10, v1.11
Although v1.9 is still compatible, we recommend upgrading to one of the supported versions.
All prior versions of docker will not be supported.
ThirdPartyResource
If you use ThirdPartyResource objects, they have moved from being namespaced-scoped to be cluster-scoped. Before upgrading to 1.3.0, export and delete any existing ThirdPartyResource objects using a 1.2.x client:
[kubelet] Allow opting out of automatic cloud provider detection in kubelet. By default kubelet will auto-detect cloud providers (#28258, @vishh)
If you use one of the kube-dns replication controller manifest in cluster/saltbase/salt/kube-dns, i.e. cluster/saltbase/salt/kube-dns/{skydns-rc.yaml.base,skydns-rc.yaml.in}, either substitute one of __PILLAR__FEDERATIONS__DOMAIN__MAP__ or {{ pillar['federations_domain_map'] }} with the corresponding federation name to domain name value or remove them if you do not support cluster federation at this time. If you plan to substitute the parameter with its value, here is an example for {{ pillar['federations_domain_map'] } (#28132, @madhusudancs)
Init containers enable pod authors to perform tasks before their normal containers start. Each init container is started in order, and failing containers will prevent the application from starting. (#23666, @smarterclayton)
Other notable changes
GCE provider: Limit Filter calls to regexps rather than large blobs (#27741, @zmerlynn)
Show LASTSEEN, the sorting key, as the first column in kubectl get event output (#27549, @therc)
Change default value of deleting-pods-burst to 1 (#27422, @gmarek)
A new volume manager was introduced in kubelet that synchronizes volume mount/unmount (and attach/detach, if attach/detach controller is not enabled). (#26801, @saad-ali)
This eliminates the race conditions between the pod creation loop and the orphaned volumes loops. It also removes the unmount/detach from the syncPod() path so volume clean up never blocks the syncPod loop.
This fixed environments where CPU and Memory Accounting were not enabled on the unit that launched the kubelet or docker from reporting the root cgroup when monitoring usage stats for those components.
New default horizontalpodautoscaler/v1 generator for kubectl autoscale. (#26775, @piosz)
Use autoscaling/v1 in kubectl by default.
federation: Adding dnsprovider flags to federation-controller-manager (#27158, @nikhiljindal)
federation service controller: fixing a bug so that existing services are created in newly registered clusters (#27028, @mfanjie)
Rename environment variables (KUBE_)ENABLE_NODE_AUTOSCALER to (KUBE_)ENABLE_CLUSTER_AUTOSCALER. (#27117, @mwielgus)
Kubernetes v1.3 introduces a new Attach/Detach Controller. This controller manages attaching and detaching of volumes on-behalf of nodes. (#26351, @saad-ali)
This ensures that attachment and detachment of volumes is independent of any single nodes’ availability. Meaning, if a node or kubelet becomes unavailable for any reason, the volumes attached to that node will be detached so they are free to be attached to other nodes.
Specifically the new controller watches the API server for scheduled pods. It processes each pod and ensures that any volumes that implement the volume Attacher interface are attached to the node their pod is scheduled to.
When a pod is deleted, the controller waits for the volume to be safely unmounted by kubelet. It does this by waiting for the volume to no longer be present in the nodes Node.Status.VolumesInUse list. If the volume is not safely unmounted by kubelet within a pre-configured duration (3 minutes in Kubernetes v1.3), the controller unilaterally detaches the volume (this prevents volumes from getting stranded on nodes that become unavailable).
In order to remain backwards compatible, the new controller only manages attach/detach of volumes that are scheduled to nodes that opt-in to controller management. Nodes running v1.3 or higher of Kubernetes opt-in to controller management by default by setting the "volumes.kubernetes.io/controller-managed-attach-detach" annotation on the Node object on startup. This behavior is gated by a new kubelet flag, "enable-controller-attach-detach,” (default true).
In order to safely upgrade an existing Kubernetes cluster without interruption of volume attach/detach logic:
First upgrade the master to Kubernetes v1.3.
This will start the new attach/detach controller.
The new controller will initially ignore volumes for all nodes since they lack the "volumes.kubernetes.io/controller-managed-attach-detach" annotation.
Then upgrade nodes to Kubernetes v1.3.
As nodes are upgraded, they will automatically, by default, opt-in to attach/detach controller management, which will cause the controller to start managing attaches/detaches for volumes that get scheduled to those nodes.
Move shell completion generation into 'kubectl completion' command (#23801, @sttts)
Fix strategic merge diff list diff bug (#26418, @AdoHe)
Setting TLS1.2 minimum because TLS1.0 and TLS1.1 are vulnerable (#26169, @victorgp)
Kubelet: Periodically reporting image pulling progress in log (#26145, @Random-Liu)
Federation service controller is one key component of federation controller manager, it watches federation service, creates/updates services to all registered clusters, and update DNS records to global DNS server. (#26034, @mfanjie)
With this PR, kubectl and other RestClient's using the AuthProvider framework can make OIDC authenticated requests, and, if there is a refresh token present, the tokens will be refreshed as needed. (#25270, @bobbyrullo)
Make addon-manager cross-platform and use it with hyperkube (#25631, @luxas)
kubelet: Optionally, have kubelet exit if lock file contention is observed, using --exit-on-lock-contention flag (#25596, @derekparker)
kubectl "rm" will suggest using "delete"; "ps" and "list" will suggest "get". (#25181, @janetkuo)
Add IPv6 address support for pods - does NOT include services (#23090, @tgraf)
Use local disk for ConfigMap volume instead of tmpfs (#25306, @pmorie)
Alpha support for scheduling pods on machines with NVIDIA GPUs whose kubelets use the --experimental-nvidia-gpus flag, using the alpha.kubernetes.io/nvidia-gpu resource (#24836, @therc)
AWS: SSL support for ELB listeners through annotations (#23495, @therc)
Implement kubectl rollout status that can be used to watch a deployment's rollout status (#19946, @janetkuo)
Significant scale improvements. Increased cluster scale by 400% to 1000 nodes with 30,000 pods per cluster.
Kubelet supports 100 pods per node with 4x reduced system overhead.
Simplified application deployment and management.
Dynamic Configuration (ConfigMap API in the core API group) enables application
configuration to be stored as a Kubernetes API object and pulled dynamically on
container startup, as an alternative to baking in command-line flags when a
container is built.
Turnkey Deployments (Deployment API (Beta) in the Extensions API group)
automate deployment and rolling updates of applications, specified
declaratively. It handles versioning, multiple simultaneous rollouts,
aggregating status across all pods, maintaining application availability, and
rollback.
Automated cluster management:
Kubernetes clusters can now span zones within a cloud provider. Pods from a
service will be automatically spread across zones, enabling applications to
tolerate zone failure.
Simplified way to run a container on every node (DaemonSet API (Beta) in the
Extensions API group): Kubernetes can schedule a service (such as a logging
agent) that runs one, and only one, pod per node.
TLS and L7 support (Ingress API (Beta) in the Extensions API group): Kubernetes
is now easier to integrate into custom networking environments by supporting
TLS for secure communication and L7 http-based traffic routing.
Graceful Node Shutdown (aka drain) - The new “kubectl drain” command gracefully
evicts pods from nodes in preparation for disruptive operations like kernel
upgrades or maintenance.
Custom Metrics for Autoscaling (HorizontalPodAutoscaler API in the Autoscaling
API group): The Horizontal Pod Autoscaling feature now supports custom metrics
(Alpha), allowing you to specify application-level metrics and thresholds to
trigger scaling up and down the number of pods in your application.
New GUI (dashboard) allows you to get started quickly and enables the same
functionality found in the CLI as a more approachable and discoverable way of
interacting with the system. Note: the GUI is enabled by default in 1.2 clusters.
The previous version, apiVersion: extensions/v1beta1, is still supported. Even if you roll back to 1.1, the objects created using
the new apiVersion will still be accessible, using the old version. You can
continue to use your existing JSON and YAML files until you are ready to switch
to batch/v1. We may remove support for Jobs with apiVersion: extensions/v1beta1 in 1.3 or 1.4.
HorizontalPodAutoscaler was Beta in 1.1 and is GA in 1.2 .
apiVersion: autoscaling/v1 is now available. Changes in this version are:
Field CPUUtilization which was a nested structure CPUTargetUtilization in
HorizontalPodAutoscalerSpec was replaced by TargetCPUUtilizationPercentage
which is an integer.
ScaleRef of type SubresourceReference in HorizontalPodAutoscalerSpec which
referred to scale subresource of the resource being scaled was replaced by
ScaleTargetRef which points just to the resource being scaled.
In extensions/v1beta1 if CPUUtilization in HorizontalPodAutoscalerSpec was not
specified it was set to 80 by default while in autoscaling/v1 HPA object
without TargetCPUUtilizationPercentage specified is a valid object. Pod
autoscaler controller will apply a default scaling policy in this case which is
equivalent to the previous one but may change in the future.
The previous version, apiVersion: extensions/v1beta1, is still supported. Even if you roll back to 1.1, the objects created using
the new apiVersions will still be accessible, using the old version. You can
continue to use your existing JSON and YAML files until you are ready to switch
to autoscaling/v1. We may remove support for HorizontalPodAutoscalers with apiVersion: extensions/v1beta1 in 1.3 or 1.4.
Kube-Proxy now defaults to an iptables-based proxy. If the --proxy-mode flag is
specified while starting kube-proxy (‘userspace’ or ‘iptables’), the flag value
will be respected. If the flag value is not specified, the kube-proxy respects
the Node object annotation: ‘net.beta.kubernetes.io/proxy-mode’. If the
annotation is not specified, then ‘iptables’ mode is the default. If kube-proxy
is unable to start in iptables mode because system requirements are not met
(kernel or iptables versions are insufficient), the kube-proxy will fall-back
to userspace mode. Kube-proxy is much more performant and less
resource-intensive in ‘iptables’ mode.
Node stability can be improved by reserving resources for the base operating system using --system-reserved and --kube-reserved Kubelet flags
Liveness and readiness probes now support more configuration parameters:
periodSeconds, successThreshold, failureThreshold
The new ReplicaSet API (Beta) in the Extensions API group is similar to
ReplicationController, but its selector is more general (supports set-based selector; whereas ReplicationController
only supports equality-based selector).
Scale subresource support is now expanded to ReplicaSets along with
ReplicationControllers and Deployments. Scale now supports two different types
of selectors to accommodate both equality-based selectors supported by ReplicationControllers and set-based selectors supported by Deployments and ReplicaSets.
“kubectl run” now produces Deployments (instead of ReplicationControllers) and
Jobs (instead of Pods) by default.
Pods can now consume Secret data in environment variables and inject those
environment variables into a container’s command-line args.
Stable version of Heapster which scales up to 1000 nodes: more metrics, reduced
latency, reduced cpu/memory consumption (~4mb per monitored node).
Pods now have a security context which allows users to specify:
attributes which apply to the whole pod:
User ID
Whether all containers should be non-root
Supplemental Groups
FSGroup - a special supplemental group
SELinux options
If a pod defines an FSGroup, that Pod’s system (emptyDir, secret, configMap,
etc) volumes and block-device volumes will be owned by the FSGroup, and each
container in the pod will run with the FSGroup as a supplemental group
Volumes that support SELinux labelling are now automatically relabeled with the
Pod’s SELinux context, if specified
A stable client library release_1_2 is added. The library is here, and detailed doc is here. We will keep the interface of this go client stable.
New Azure File Service Volume Plugin enables mounting Microsoft Azure File
Volumes (SMB 2.1 and 3.0) into a Pod. See example for details.
Logs usage and root filesystem usage of a container, volumes usage of a pod and node disk usage are exposed through Kubelet new metrics API.
Experimental Features
Dynamic Provisioning of PersistentVolumes: Kubernetes previously required all
volumes to be manually provisioned by a cluster administrator before use. With
this feature, volume plugins that support it (GCE PD, AWS EBS, and Cinder) can
automatically provision a PersistentVolume to bind to an unfulfilled
PersistentVolumeClaim.
Run multiple schedulers in parallel, e.g. one or more custom schedulers
alongside the default Kubernetes scheduler, using pod annotations to select
among the schedulers for each pod. Documentation is here, design doc is here.
More expressive node affinity syntax, and support for “soft” node affinity.
Node selectors (to constrain pods to schedule on a subset of nodes) now support
the operators {In, NotIn, Exists, DoesNotExist, Gt, Lt} instead of just conjunction of exact match on node label values. In
addition, we’ve introduced a new “soft” kind of node selector that is just a
hint to the scheduler; the scheduler will try to satisfy these requests but it
does not guarantee they will be satisfied. Both the “hard” and “soft” variants
of node affinity use the new syntax. Documentation is here (see section “Alpha feature in Kubernetes v1.2: Node Affinity“). Design doc is here.
A pod can specify its own Hostname and Subdomain via annotations (pod.beta.kubernetes.io/hostname, pod.beta.kubernetes.io/subdomain). If the Subdomain matches the name of a headless service in the same namespace, a DNS A record is also created for the pod’s FQDN. More
details can be found in the DNS README. Changes were introduced in PR #20688.
New SchedulerExtender enables users to implement custom
out-of-(the-scheduler)-process scheduling predicates and priority functions,
for example to schedule pods based on resources that are not directly managed
by Kubernetes. Changes were introduced in PR #13580. Example configuration and documentation is available here. This is an alpha feature and may not be supported in its current form at beta
or GA.
New Flex Volume Plugin enables users to use out-of-process volume plugins that
are installed to “/usr/libexec/kubernetes/kubelet-plugins/volume/exec/” on
every node, instead of being compiled into the Kubernetes binary. See example for details.
vendor volumes into a pod. It expects vendor drivers are installed in the
volume plugin path on each kubelet node. This is an alpha feature and may
change in future.
Kubelet exposes a new Alpha metrics API - /stats/summary in a user friendly format with reduced system overhead. The measurement is done in PR #22542.
Action required
Docker v1.9.1 is officially recommended. Docker v1.8.3 and Docker v1.10 are
supported. If you are using an older release of Docker, please upgrade. Known
issues with Docker 1.9.1 can be found below.
CPU hardcapping will be enabled by default for containers with CPU limit set,
if supported by the kernel. You should either adjust your CPU limit, or set CPU
request only, if you want to avoid hardcapping. If the kernel does not support
CPU Quota, NodeStatus will contain a warning indicating that CPU Limits cannot
be enforced.
The following applies only if you use the Go language client (/pkg/client/unversioned) to create Job by defining Go variables of type "k8s.io/kubernetes/pkg/apis/extensions".Job). We think this is not common, so if you are not sure what this means, you probably aren't doing this. If
you do this, then, at the time you re-vendor the "k8s.io/kubernetes/" code, you will need to set job.Spec.ManualSelector = true, or else set job.Spec.Selector = nil. Otherwise, the jobs you create may be rejected. See Specifying your own pod selector.
Deployment was Alpha in 1.1 (though it had apiVersion extensions/v1beta1) and
was disabled by default. Due to some non-backward-compatible API changes, any
Deployment objects you created in 1.1 won’t work with in the 1.2 release.
Before upgrading to 1.2, delete all Deployment alpha-version resources, including the Replication Controllers and Pods the Deployment manages. Then
create Deployment Beta resources after upgrading to 1.2. Not deleting the
Deployment objects may cause the deployment controller to mistakenly match
other pods and delete them, due to the selector API change.
Client (kubectl) and server versions must match (both 1.1 or both 1.2) for any
Deployment-related operations.
Behavior change:
Deployment creates ReplicaSets instead of ReplicationControllers.
Scale subresource now has a new targetSelector field in its status. This field supports the new set-based selectors supported
by Deployments, but in a serialized format.
Spec change:
Deployment’s selector is now more general (supports set-based selector; it only supported
equality-based selector in 1.1).
.spec.uniqueLabelKey is removed -- users can’t customize unique label key --
and its default value is changed from
“deployment.kubernetes.io/podTemplateHash” to “pod-template-hash”.
.spec.strategy.rollingUpdate.minReadySeconds is moved to .spec.minReadySeconds
DaemonSet was Alpha in 1.1 (though it had apiVersion extensions/v1beta1) and
was disabled by default. Due to some non-backward-compatible API changes, any
DaemonSet objects you created in 1.1 won’t work with in the 1.2 release.
Before upgrading to 1.2, delete all DaemonSet alpha-version resources. If you do not want to disrupt the pods, use kubectl delete daemonset
--cascade=false. Then create DaemonSet Beta resources after upgrading to 1.2.
Client (kubectl) and server versions must match (both 1.1 or both 1.2) for any
DaemonSet-related operations.
Behavior change:
DaemonSet pods will be created on nodes with .spec.unschedulable=true and will
not be evicted from nodes whose Ready condition is false.
Updates to the pod template are now permitted. To perform a rolling update of a
DaemonSet, update the pod template and then delete its pods one by one; they
will be replaced using the updated template.
Spec change:
DaemonSet’s selector is now more general (supports set-based selector; it only supported
equality-based selector in 1.1).
Running against a secured etcd requires these flags to be passed to
kube-apiserver (instead of --etcd-config):
--etcd-certfile, --etcd-keyfile (if using client cert auth)
--etcd-cafile (if not using system roots)
As part of preparation in 1.2 for adding support for protocol buffers (and the
direct YAML support in the API available today), the Content-Type and Accept
headers are now properly handled as per the HTTP spec. As a consequence, if
you had a client that was sending an invalid Content-Type or Accept header to
the API, in 1.2 you will either receive a 415 or 406 error.
The only client
this is known to affect is curl when you use -d with JSON but don't set a
content type, helpfully sends "application/x-www-urlencoded", which is not
correct.
Other client authors should double check that you are sending proper
accept and content type headers, or set no value (in which case JSON is the
default).
An example using curl:
curl -H "Content-Type: application/json" -XPOST -d
'{"apiVersion":"v1","kind":"Namespace","metadata":{"name":"kube-system"}}' "http://127.0.0.1:8080/api/v1/namespaces"
The version of InfluxDB is bumped from 0.8 to 0.9 which means storage schema
change. More details here.
We have renamed “minions” to “nodes”. If you were specifying NUM_MINIONS or
MINION_SIZE to kube-up, you should now specify NUM_NODES or NODE_SIZE.
Known Issues
Paused deployments can't be resized and don't clean up old ReplicaSets.
Minimum memory limit is 4MB. This is a docker limitation
Minimum CPU limits is 10m. This is a Linux Kernel limitation
“kubectl rollout undo” (i.e. rollback) will hang on paused deployments, because
paused deployments can’t be rolled back (this is expected), and the command
waits for rollback events to return the result. Users should use “kubectl
rollout resume” to resume a deployment before rolling back.
“kubectl edit ” will open the editor multiple times, once for each
resource in the list.
If you create HPA object using autoscaling/v1 API without specifying
targetCPUUtilizationPercentage and read it using kubectl it will print default
value as specified in extensions/v1beta1 (see details in #23196).
If a node or kubelet crashes with a volume attached, the volume will remain
attached to that node. If that volume can only be attached to one node at a
time (GCE PDs attached in RW mode, for example), then the volume must be
manually detached before Kubernetes can attach it to other nodes.
If a volume is already attached to a node any subsequent attempts to attach it
again (due to kubelet restart, for example) will fail. The volume must either
be manually detached first or the pods referencing it deleted (which would
trigger automatic volume detach).
In very large clusters it may happen that a few nodes won’t register in API
server in a given timeframe for whatever reasons (networking issue, machine
failure, etc.). Normally when kube-up script will encounter even one NotReady
node it will fail, even though the cluster most likely will be working. We
added an environmental variable to kube-up ALLOWED_NOTREADY_NODES that
defines the number of nodes that if not Ready in time won’t cause kube-up
failure.
“kubectl rolling-update” only supports Replication Controllers (it doesn’t
support Replica Sets). It’s recommended to use Deployment 1.2 with “kubectl
rollout” commands instead, if you want to rolling update Replica Sets.
When live upgrading Kubelet to 1.2 without draining the pods running on the node,
the containers will be restarted by Kubelet (see details in #23104).
Docker Known Issues
1.9.1
Listing containers can be slow at times which will affect kubelet performance.
More information here
Docker daemon restarts can fail. Docker checkpoints have to deleted between
restarts. More information here
Pod IP allocation-related issues. Deleting the docker checkpoint prior to
restarting the daemon alleviates this issue, but hasn’t been verified to
completely eliminate the IP allocation issue. More information here
Daemon becomes unresponsive (rarely) due to kernel deadlocks. More information here
Provider-specific Notes
Various
Core changes:
Support for load balancers with source ranges
AWS
Core changes:
Support for ELBs with complex configurations: better subnet selection with
multiple subnets, and internal ELBs
Support for VPCs with private dns names
Multiple fixes to EBS volume mounting code for robustness, and to support
mounting the full number of AWS recommended volumes.
Multiple fixes to avoid hitting AWS rate limits, and to throttle if we do
Support for the EC2 Container Registry (currently in us-east-1 only)
With kube-up:
Automatically install updates on boot & reboot
Use optimized image based on Jessie by default
Add support for Ubuntu Wily
Master is configured with automatic restart-on-failure, via CloudWatch
Bootstrap reworked to be more similar to GCE; better supports reboots/restarts
Use an elastic IP for the master by default
Experimental support for node spot instances (set NODE_SPOT_PRICE=0.05)
