The Kubelet assumes Docker is running during its execution and on
machine boot it is a race between Docker coming up and Kubelet calling
Docker. This PR waits for Docker to be up before the Kubelet begins
doing useful work. On timeout, Kubelet exits and expects to be
restarted.
Part of multi-port services.
If people like this, we could start to apply this pattern elsewhere.
TL;DR: don't redefine objects over and over changing one thing each
time. Instead provide a func that mutates a base object to test facets
of validation. Much easier to read and to update.
Hostname behavior across operating systems is inconsistent (Macs can
have uppercase host names, so can some other systems). In general,
always strings.ToLower(os.Hostname()).
There are two main goals for this change.
1. Fix the naming scheme in kubelet so that it accepts DNS subdomain
name/namespaces correctly (#4920). The design is discussed in #3453.
2. Prepare for syncing the static pods back to the apiserver(#4090). This
includes
- Eliminate the source component in the internal full pod name (#4922). Pods
no longer need sources as they will all be sync'd via apiserver.
- Changing the naming scheme for the static (file-, http-, and etcd-based)
pods such that they are distinguishable when syncing back to the apiserver.
The changes includes:
* name = <pod.Name>-<hostname>
* namespace = <cluster_namespace> (i.e. "default" for now).
* container_name = k8s_<contianer_name>.<hash_of_container>_<pod_name>_<namespace>_<uid>_<random>
Note that this is not backward-compatible, meaning the kubelet won't recognize
existing running containers using the old naming scheme.
All images are tracked, when they were created and when they were last
used. FreeSpace() evicts these images in least recently used order,
breaking ties with oldest first.
When a host port conflict is detected, kubelet should set the pod status to
fail. The failed status will then be polled by other components at a later time,
which allows replication controller to create a new pod if necessary.
To achieve this, this change stores the pod status information in a status map
upon the detecton of port conflict. GetPodStatus() consults this status map
before attempting to query docker. The entries in the status map will be removed
when the pod is no longer associated with the node.
