Package ganeti :: Module vcluster

Module vcluster

Module containing utilities for virtual clusters.

Most functions manipulate file system paths and are no-ops when the environment variables GANETI_ROOTDIR and GANETI_HOSTNAME are not set. See the functions' docstrings for details.

Functions

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string

_GetRootDirectory(envname)
Retrieves root directory from an environment variable.

source code

string

_GetHostname(envname)
Retrieves virtual hostname from an environment variable.

source code

_CheckHostname(hostname)
Very basic check for hostnames.

source code

tuple; (string, string, string or None)

_PreparePaths(rootdir, hostname)
Checks if the root directory and hostname are acceptable.

source code

string or None

GetVirtualHostname()
Returns the virtual hostname.

source code

MakeNodeRoot(base, node_name)
Appends a node name to the base directory.

source code

ExchangeNodeRoot(node_name, filename, _basedir=_VIRT_BASEDIR, _noderoot=_VIRT_NODEROOT)
Replaces the node-specific root directory in a path.

source code

EnvironmentForHost(hostname, _basedir=_VIRT_BASEDIR)
Returns the environment variables for a host.

source code

AddNodePrefix(path, _noderoot=_VIRT_NODEROOT)
Adds a node-specific prefix to a path in a virtual cluster.

source code

_RemoveNodePrefix(path, _noderoot=_VIRT_NODEROOT)
Removes the node-specific prefix from a path.

source code

MakeVirtualPath(path, _noderoot=_VIRT_NODEROOT)
Virtualizes a path.

source code

LocalizeVirtualPath(path, _noderoot=_VIRT_NODEROOT)
Localizes a virtual path.

source code

Variables

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ETC_HOSTS = "/etc/hosts"

_VIRT_PATH_PREFIX = "/###-VIRTUAL-PATH-###,"

_ROOTDIR_ENVNAME = "GANETI_ROOTDIR"

_HOSTNAME_ENVNAME = "GANETI_HOSTNAME"

_VPATH_WHITELIST = compat.UniqueFrozenset([ETC_HOSTS,])
List of paths which shouldn't be virtualized

Imports: os, compat

Function Details

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_GetRootDirectory(envname)

source code

Retrieves root directory from an environment variable.

Parameters:

envname (string) - Environment variable name

Returns: string

Root directory (can be empty)

_GetHostname(envname)

source code

Retrieves virtual hostname from an environment variable.

Parameters:

envname (string) - Environment variable name

Returns: string

Host name (can be empty)

_CheckHostname(hostname)

source code

Very basic check for hostnames.

Parameters:

hostname (string) - Hostname

_PreparePaths(rootdir, hostname)

source code

Checks if the root directory and hostname are acceptable.

The (node-specific) root directory must have the hostname as its last component. The parent directory then becomes the cluster-wide root directory. This is necessary as some components must be able to predict the root path on a remote node (e.g. copying files via scp).

Parameters:

rootdir (string) - Root directory (from environment)
hostname (string) - Hostname (from environment)

Returns: tuple; (string, string, string or None)

Tuple containing cluster-global root directory, node root directory and virtual hostname

ExchangeNodeRoot(node_name, filename, _basedir=_VIRT_BASEDIR, _noderoot=_VIRT_NODEROOT)

source code

Replaces the node-specific root directory in a path.

Replaces it with the root directory for another node. Assuming /tmp/vcluster/node1 is the root directory for node1, the result will be /tmp/vcluster/node3 for node3 (as long as a root directory is specified in the environment).

AddNodePrefix(path, _noderoot=_VIRT_NODEROOT)

source code

Adds a node-specific prefix to a path in a virtual cluster.

Returned path includes user-specified root directory if specified in environment. As an example, the path /var/lib/ganeti becomes /tmp/vcluster/node1/var/lib/ganeti if /tmp/vcluster/node1 is the root directory specified in the environment.

_RemoveNodePrefix(path, _noderoot=_VIRT_NODEROOT)

source code

Removes the node-specific prefix from a path.

This is the opposite of AddNodePrefix and removes a node-local prefix path.

MakeVirtualPath(path, _noderoot=_VIRT_NODEROOT)

source code

Virtualizes a path.

A path is "virtualized" by stripping it of its node-specific directory and prepending a prefix (_VIRT_PATH_PREFIX). Use LocalizeVirtualPath to undo the process. Virtual paths are meant to be transported via RPC.

LocalizeVirtualPath(path, _noderoot=_VIRT_NODEROOT)

source code

Localizes a virtual path.

A "virtualized" path consists of a prefix (LocalizeVirtualPath) and a local path. This function adds the node-specific directory to the local path. Virtual paths are meant to be transported via RPC.