Split out the Python package from the README. (#736)

The description of the Python package belongs in the Python package
directory.

1 files changed, 1 insertions, 243 deletions

diff --git a/README.md b/README.md
index 8b06b61..f7b698b 100644
--- a/README.md
+++ b/README.md
@@ -8,20 +8,6 @@ Compute Engine [images](https://cloud.google.com/compute/docs/images).
 **Table of Contents**
 
 * [Background](#background)
-* [Guest Overview](#guest-overview)
-* [Common Libraries](#common-libraries)
-    * [Metadata Watcher](#metadata-watcher)
-    * [Logging](#logging)
-    * [Configuration Management](#configuration-management)
-    * [File Management](#file-management)
-    * [Network Utilities](#network-utilities)
-* [Daemons](#daemons)
-    * [Accounts](#accounts)
-    * [Clock Skew](#clock-skew)
-    * [Network](#network)
-* [Instance Setup](#instance-setup)
-* [Metadata Scripts](#metadata-scripts)
-* [Configuration](#configuration)
 * [Packaging](#packaging)
     * [Version Updates](#version-updates)
     * [Package Distribution](#package-distribution)
@@ -40,234 +26,6 @@ The Linux guest environment includes a set of scripts and daemons (long-running
 processes) that read the content of the metadata server to make a virtual
 machine run properly on our platform.
 
-## Guest Overview
-
-The Linux guest environment is made up of the following components:
-
-*   **Accounts** daemon to setup and manage user accounts, and to enable SSH key
-    based authentication.
-*   **Clock skew** daemon to keep the system clock in sync after VM start and
-    stop events.
-*   **Disk expand** scripts to expand the VM root partition for CentOS 6,
-    CentOS 7, RHEL 6, and RHEL 7 images.
-*   **Instance setup** scripts to execute VM configuration scripts during boot.
-*   **Network** daemon that handles network setup for multiple network interfaces
-    on boot and integrates network load balancing with
-    forwarding rule changes into the guest.
-*   **Metadata scripts** to run user-provided scripts at VM startup and
-    shutdown.
-
-The Linux guest environment is written in Python and is version agnostic
-between Python 2.6 and 3.5. There is complete unittest coverage for every Python
-library and script. The design of various guest libraries, daemons, and scripts,
-are detailed in the sections below.
-
-## Common Libraries
-
-The Python libraries are shared with each of the daemons and the instance setup
-tools.
-
-#### Metadata Watcher
-
-The guest environment relies upon retrieving content from the metadata server to
-configure the VM environment. A metadata watching library handles all
-communication with the metadata server.
-
-The library exposes two functions:
-
-*   **GetMetadata** immediately retrieves the contents of the metadata server
-    for a given metadata key. The function catches and logs any connection
-    related exceptions. The metadata server content is returned as a
-    deserialized JSON object.
-*   **WatchMetadata** continuously makes a hanging GET, watching for changes to
-    the specified contents of the metadata server. When the request closes, the
-    watcher verifies the etag was updated. In case of an update, the etag is
-    updated and a provided handler function is called with the deserialized JSON
-    metadata content. The WatchMetadata function should never terminate; it
-    catches and logs any connection related exceptions, and catches and logs any
-    exception generated from calling the handler.
-
-Metadata server requests have custom retry logic for metadata server
-unavailability; by default, any request has one minute to complete before the
-request is cancelled. In case of a brief network outage where the metadata
-server is unavailable, there is a short delay between retries.
-
-#### Logging
-
-The Google added daemons and scripts write to the serial port for added
-transparency. A common logging library is a thin wrapper around the Python
-logging module. The library configures appropriate SysLog handlers, sets the
-logging formatter, and provides a debug options for added logging and console
-output.
-
-#### Configuration Management
-
-A configuration file allows users to disable daemons and modify instance setup
-behaviors from a single location. Guest environment daemons and scripts need a
-mechanism to integrate user settings into the guest. A configuration management
-library retrieves and modifies these settings.
-
-The library exposes the following functions:
-
-*   **GetOptionString** retrieves the value for a configuration option. The type
-    of the value is a string if set.
-*   **GetOptionBool** retrieves the value for a configuration option. The type
-    of the value is a boolean if set.
-*   **SetOption** sets the value of an option in the config file. An overwrite
-    flag specifies whether to replace an existing value.
-*   **WriteConfig** writes the configuration values to a file. The function is
-    responsible for locking the file, preventing concurrent writes, and writing
-    a file header if one is provided.
-
-#### File Management
-
-Guest environment daemons and scripts use a common library for file management.
-The library provides the following functions:
-
-*   **SetPermissions** unifies the logic to set permissions and simplify file
-    creation across the various Linux distributions. The function sets the mode,
-    UID, and GID, of a provided path. On supported OS configurations that user
-    SELinux, the SELinux context is automatically set.
-*   **LockFile** is a context manager that simplifies the process of file
-    locking in Python. The function sets up an `flock` and releases the lock on
-    exit.
-
-#### Network Utilities
-
-A network-utilities library retrieves information about a network interface. The
-library is used for IP forwarding and for setting up an Ethernet interface on
-boot. The library exposes a `GetNetworkInterface` function that retrieves the
-network interface name associated with a MAC address.
-
-## Daemons
-
-The guest environment daemons import and use the common libraries described
-above. Each daemon reads the configuration file before execution. This allows a
-user to easily disable undesired functionality. Additional daemon behaviors are
-detailed below.
-
-#### Accounts
-
-The accounts daemon is responsible for provisioning and deprovisioning user
-accounts. The daemon grants permissions to user accounts, and updates the list
-of authorized keys that have access to accounts based on metadata SSH key
-updates. User account creation is based on
-[adding and remove SSH Keys](https://cloud.google.com/compute/docs/instances/adding-removing-ssh-keys)
-stored in metadata.
-
-The accounts management daemon has the following behaviors.
-
-*   Administrator permissions are managed with a `google-sudoers` Linux group.
-*   All users provisioned by the account daemon are added to the
-    `google-sudoers` group.
-*   The daemon stores a file in the guest to preserve state for the user
-    accounts managed by Google.
-*   The authorized keys file for a Google managed user is deleted when all SSH
-    keys for the user are removed from metadata.
-*   User accounts not managed by Google are not modified by the accounts daemon.
-
-#### Clock Skew
-
-The clock skew daemon is responsible for syncing the software clock with the
-hypervisor clock after a stop/start event or after a migration. Preventing clock
-skew may result in `system time has changed` messages in VM logs.
-
-#### Network
-
-The network daemon uses network interface metadata to manage the network
-interfaces in the guest by performing the following tasks:
-
-*   Enabled all associated network interfaces on boot. Network interfaces are
-    specified by MAC address in instance metadata.
-*   Uses IP forwarding metadata to setup or remove IP routes in the guest.
-    *   Only IPv4 IP addresses are currently supported.
-    *   Routes are set on the default Ethernet interface determined dynamically.
-    *   Google routes are configured, by default, with the routing protocol ID
-        `66`. This ID is a namespace for daemon configured IP addresses.
-
-## Instance Setup
-
-Instance setup runs during VM boot. The script configures the Linux guest
-environment by performing the following tasks.
-
-*   Optimize for local SSD.
-*   Enable multi-queue on all the virtionet devices.
-*   Wait for network availability.
-*   Set SSH host keys the first time the instance is booted.
-*   Set the `boto` config for using Google Cloud Storage.
-*   Create the defaults configuration file.
-
-The defaults configuration file incorporates any user provided setting in
-`/etc/default/instance_configs.cfg.template` and does not override other
-conflicting settings. This allows package updates without overriding user
-configuration.
-
-## Metadata Scripts
-
-Metadata scripts implement support for running user provided
-[startup scripts](https://cloud.google.com/compute/docs/startupscript) and
-[shutdown scripts](https://cloud.google.com/compute/docs/shutdownscript). The
-guest support for metadata scripts is implemented in Python with the following
-design details.
-
-*   Metadata scripts are executed in a shell.
-*   If multiple metadata keys are specified (e.g. `startup-script` and
-    `startup-script-url`) both are executed.
-*   If multiple metadata keys are specified (e.g. `startup-script` and
-    `startup-script-url`) a URL is executed first.
-*   The exit status of a metadata script is logged after completed execution.
-
-## Configuration
-
-Users of Google provided images may configure the guest environment behaviors
-using a configuration file. To make configuration changes, add settings to
-`/etc/default/instance_configs.cfg.template`. If you are attempting to change
-the behavior of a running instance, run `/usr/bin/google_instance_setup` before
-reloading the affected daemons.
-
-Linux distributions looking to include their own defaults can specify settings
-in `/etc/default/instance_configs.cfg.distro`. These settings will not override
-`/etc/default/instance_configs.cfg.template`. This enables distribution settings
-that do not override user configuration during package update.
-
-The following are valid user configuration options.
-
-Section           | Option                 | Value
------------------ | ---------------------- | -----
-Accounts          | deprovision\_remove    | `true` makes deprovisioning a user destructive.
-Accounts          | groups                 | Comma separated list of groups for newly provisioned users.
-Accounts          | useradd\_cmd           | Command string to create a new user.
-Accounts          | userdel\_cmd           | Command string to delete a user.
-Accounts          | usermod\_cmd           | Command string to modify a user's groups.
-Accounts          | gpasswd\_add\_cmd      | Command string to add a user to a group.
-Accounts          | gpasswd\_remove\_cmd   | Command string to remove a user from a group.
-Accounts          | groupadd\_cmd          | Command string to create a new group.
-Daemons           | accounts\_daemon       | `false` disables the accounts daemon.
-Daemons           | clock\_skew\_daemon    | `false` disables the clock skew daemon.
-Daemons           | ip\_forwarding\_daemon | `false` (deprecated) skips IP forwarding.
-Daemons           | network\_daemon        | `false` disables the network daemon.
-InstanceSetup     | host\_key\_types       | Comma separated list of host key types to generate.
-InstanceSetup     | optimize\_local\_ssd   | `false` prevents optimizing for local SSD.
-InstanceSetup     | network\_enabled       | `false` skips instance setup functions that require metadata.
-InstanceSetup     | set\_boto\_config      | `false` skips setting up a `boto` config.
-InstanceSetup     | set\_host\_keys        | `false` skips generating host keys on first boot.
-InstanceSetup     | set\_multiqueue        | `false` skips multiqueue driver support.
-IpForwarding      | ethernet\_proto\_id    | Protocol ID string for daemon added routes.
-IpForwarding      | ip\_aliases            | `false` disables setting up alias IP routes.
-IpForwarding      | target\_instance\_ips  | `false` disables internal IP address load balancing.
-MetadataScripts   | default\_shell         | String with the default shell to execute scripts.
-MetadataScripts   | run\_dir               | String base directory where metadata scripts are executed.
-MetadataScripts   | startup                | `false` disables startup script execution.
-MetadataScripts   | shutdown               | `false` disables shutdown script execution.
-NetworkInterfaces | setup                  | `false` skips network interface setup.
-NetworkInterfaces | ip\_forwarding         | `false` skips IP forwarding.
-NetworkInterfaces | dhclient\_script       | String path to a dhclient script used by dhclient.
-NetworkInterfaces | dhcp\_command          | String to execute to enable network interfaces.
-
-Setting `network_enabled` to `false` will skip setting up host keys and the
-`boto` config in the guest. The setting may also prevent startup and shutdown
-script execution.
-
 ## Packaging
 
 The guest Python code is packaged as a
@@ -304,7 +62,7 @@ We build the following packages for the Linux guest environment.
 *   `python3-google-compute-engine`
     *  The Python 3 package for Linux daemons and libraries.
 *   `google-compute-engine-oslogin`
-    *  The PAM and NSS modules for [GCE OS Login](https://cloud.google.com/compute/docs/oslogin/)
+    *  The PAM and NSS modules for [OS Login](https://cloud.google.com/compute/docs/oslogin/)
 *   `gce-disk-expand`
     *  The on-boot resize scripts for root partition.