For the purpose of package initialization, <a href="#Blank_identifier">blank</a>
variables are treated like any other variables in declarations.
</p>

<p>
The declaration order of variables declared in multiple files is determined
by the order in which the files are presented to the compiler: Variables
declared in the first file are declared before any of the variables declared
in the second file, and so on.

OpenStack cloud provider can now be specified as environment variables. When we convert the OpenStack cloud provider to run in an external process, we can now use the kubernetes Secrets capability to inject the OS_* variables. This way we can specify the cloud configuration as a configmap, and specify secrets for the userid/password information. The configmap is mounted as a file, and the secrets are made available as environment variables. The external controller itself runs as a pod/daemonset. For...

### ConfigMap
* Volumes and environment variables populated from ConfigMap and Secret objects can now tolerate the named source object or specific keys being missing, by adding `optional: true` to the volume or environment variable source specifications. ([#39981](https://github.com/kubernetes/kubernetes/pull/39981), [@fraenkel](https://github.com/fraenkel))

- Kubeadm: fix an issue with the kube-proxy container env. variables ([#84888](https://github.com/kubernetes/kubernetes/pull/84888), [@neolit123](https://github.com/neolit123))

- Added options for configuring `nf_conntrack_udp_timeout`, and `nf_conntrack_udp_timeout_stream` variables of netfilter conntrack subsystem. ([#120808](https://github.com/kubernetes/kubernetes/pull/120808), [@aroradaman](https://github.com/aroradaman))

- Added a alpha feature, behind the `RelaxedEnvironmentVariableValidation` feature gate.
  When that gate is enabled, Kubernetes allows almost all printable ASCII characters to be used in the names
  of environment variables for containers in Pods. ([#123385](https://github.com/kubernetes/kubernetes/pull/123385), [@HirazawaUi](https://github.com/HirazawaUi))

    * [prometheus-to-sd addon] Bump prometheus-to-sd to 0.3.1 to pick up security fixes, bug fixes and new features.
    * [event-exporter addon] Bump event-exporter to 0.2.3 to pick up security fixes.
* [GCP] Added env variables to control CPU requests of kube-controller-manager and kube-scheduler. ([#68823](https://github.com/kubernetes/kubernetes/pull/68823), [@loburm](https://github.com/loburm))

- Bumped Dashboard version to v1.10.0 ([#68450](https://github.com/kubernetes/kubernetes/pull/68450), [@jeefy](https://github.com/jeefy))
- Added env variables to control CPU requests of kube-controller-manager and kube-scheduler. ([#68823](https://github.com/kubernetes/kubernetes/pull/68823), [@loburm](https://github.com/loburm))

    * If you are running E2E tests which require SSH keys and you utilize environment variables to override their location, you may need to modify the environment variable set. On all providers the environment variable override can now be either an absolute path to the key or a relative path (relative to ~/.ssh). Specifically the changes are:

- Kubeadm: now sets the host `OS` environment variables when executing `crictl` during image pulls. This fixed a bug where `*PROXY` environment variables did not affect `crictl` internet connectivity. ([#110134](https://github.com/kubernetes/kubernetes/pull/110134), [@mk46](https://github.com/mk46))