Package ganeti :: Module ssh

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Module ssh

source code

Module encapsulating ssh functionality.

Classes

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SshRunner
Wrapper for SSH commands.

Functions

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tuple; (string, string, string)

GetUserFiles(user, mkdir=False, dircheck=True, kind=constants.SSHK_DSA, _homedir_fn=None)
Return the paths of a user's SSH files.

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tuple; (string, dict with string as key, tuple of (string, string) as value)

GetAllUserFiles(user, mkdir=False, dircheck=True, _homedir_fn=None)
Wrapper over GetUserFiles to retrieve files for all SSH key types.

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tuple

_SplitSshKey(key)
Splits a line for SSH's authorized_keys file. source code

AddAuthorizedKeys(file_obj, keys)
Adds a list of SSH public key to an authorized_keys file.

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HasAuthorizedKey(file_obj, key)
Check if a particular key is in the 'authorized_keys' file.

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CheckForMultipleKeys(file_obj, node_names)
Check if there is at most one key per host in 'authorized_keys' file.

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AddAuthorizedKey(file_obj, key)
Adds an SSH public key to an authorized_keys file.

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RemoveAuthorizedKeys(file_name, keys)
Removes public SSH keys from an authorized_keys file.

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RemoveAuthorizedKey(file_name, key)
Removes an SSH public key from an authorized_keys file.

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(boolean, string)

_AddPublicKeyProcessLine(new_uuid, new_key, line_uuid, line_key, found)
Processes one line of the public key file when adding a key.

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string

_AddPublicKeyElse(new_uuid, new_key)
Adds a new SSH key to the key file if it did not exist already.

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(boolean, string)

_RemovePublicKeyProcessLine(target_uuid, _target_key, line_uuid, line_key, found)
Processes a line in the public key file when aiming for removing a key.

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string

_RemovePublicKeyElse(target_uuid, _target_key)
Logs when we tried to remove a key that does not exist.

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(boolean, string)

_ReplaceNameByUuidProcessLine(node_name, _key, line_identifier, line_key, found, node_uuid=None)
Replaces a node's name with its UUID on a matching line in the key file.

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string

_ReplaceNameByUuidElse(node_uuid, node_name, _key)
Logs a debug message when we try to replace a key that is not there.

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tuple (string, string)

_ParseKeyLine(line, error_fn)
Parses a line of the public key file.

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_ManipulatePubKeyFile(target_identifier, target_key, key_file=pathutils.SSH_PUB_KEYS, error_fn=errors.ProgrammerError, process_line_fn=None, process_else_fn=None)
Manipulates the list of public SSH keys of the cluster.

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AddPublicKey(new_uuid, new_key, key_file=pathutils.SSH_PUB_KEYS, error_fn=errors.ProgrammerError)
Adds a new key to the list of public keys.

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RemovePublicKey(target_uuid, key_file=pathutils.SSH_PUB_KEYS, error_fn=errors.ProgrammerError)
Removes a key from the list of public keys.

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ReplaceNameByUuid(node_uuid, node_name, key_file=pathutils.SSH_PUB_KEYS, error_fn=errors.ProgrammerError)
Replaces a host name with the node's corresponding UUID.

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ClearPubKeyFile(key_file=pathutils.SSH_PUB_KEYS, mode=0600)
Resets the content of the public key file.

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OverridePubKeyFile(key_map, key_file=pathutils.SSH_PUB_KEYS)
Overrides the public key file with a list of given keys.

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dict mapping strings to list of strings

QueryPubKeyFile(target_uuids, key_file=pathutils.SSH_PUB_KEYS, error_fn=errors.ProgrammerError)
Retrieves a map of keys for the requested node UUIDs.

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InitSSHSetup(key_type, key_bits, error_fn=errors.OpPrereqError, _homedir_fn=None, _suffix="")
Setup the SSH configuration for the node.

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InitPubKeyFile(master_uuid, key_type, key_file=pathutils.SSH_PUB_KEYS)
Creates the public key file and adds the master node's SSH key.

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WriteKnownHostsFile(cfg, file_name)
Writes the cluster-wide equally known_hosts file.

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list of strings

_EnsureCorrectGanetiVersion(cmd)
Ensured the correct Ganeti version before running a command via SSH.

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RunSshCmdWithStdin(cluster_name, node, basecmd, port, data, debug=False, verbose=False, use_cluster_key=False, ask_key=False, strict_host_check=False, ensure_version=False)
Runs a command on a remote machine via SSH and provides input in stdin.

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ReadRemoteSshPubKeys(pub_key_file, node, cluster_name, port, ask_key, strict_host_check)
Fetches a public SSH key from a node via SSH.

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positive int

DetermineKeyBits(key_type, key_bits, old_key_type, old_key_bits)
Checks the key bits to be used for a given key type, or provides defaults.

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Variables

[hide private]

KeyBitInfo = namedtuple('KeyBitInfo', ['default', 'validation_...

SSH_KEY_VALID_BITS = {constants.SSHK_DSA: KeyBitInfo(1024, lam...

Imports: logging, os, tempfile, namedtuple, partial, utils, errors, constants, netutils, pathutils, vcluster, compat, serializer, ssconf

Function Details

[hide private]

GetUserFiles(user, mkdir=False, dircheck=True, kind=constants.SSHK_DSA, _homedir_fn=None)

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Return the paths of a user's SSH files.

Parameters:

user (string) - Username
mkdir (bool) - Whether to create ".ssh" directory if it doesn't exist
dircheck (bool) - Whether to check if ".ssh" directory exists
kind (string) - One of constants.SSHK_ALL

Returns: tuple; (string, string, string)

Tuple containing three file system paths; the private SSH key file, the public SSH key file and the user's authorized_keys file

Raises:

errors.OpExecError - When home directory of the user can not be determined
errors.OpExecError - Regardless of the mkdir parameters, this exception is raised if ~$user/.ssh is not a directory and dircheck is set to True

GetAllUserFiles(user, mkdir=False, dircheck=True, _homedir_fn=None)

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Wrapper over GetUserFiles to retrieve files for all SSH key types.

See GetUserFiles for details.

Returns: tuple; (string, dict with string as key, tuple of (string, string) as value)

_SplitSshKey(key)

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Splits a line for SSH's authorized_keys file.

If the line has no options (e.g. no command="..."), only the significant parts, the key type and its hash, are used. Otherwise the whole line is used (split at whitespace).

Parameters:

key (string) - Key line

Returns: tuple

AddAuthorizedKeys(file_obj, keys)

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Adds a list of SSH public key to an authorized_keys file.

Parameters:

file_obj (str or file handle) - path to authorized_keys file
keys (list of str) - list of strings containing keys

HasAuthorizedKey(file_obj, key)

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Check if a particular key is in the 'authorized_keys' file.

Parameters:

file_obj (str or file handle) - path to authorized_keys file
key (str) - string containing key

CheckForMultipleKeys(file_obj, node_names)

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Check if there is at most one key per host in 'authorized_keys' file.

Parameters:

file_obj (str or file handle) - path to authorized_keys file
node_names (list of str) - list of names of nodes of the cluster

Returns:

a dictionary with hostnames which occur more than once

AddAuthorizedKey(file_obj, key)

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Adds an SSH public key to an authorized_keys file.

Parameters:

file_obj (str or file handle) - path to authorized_keys file
key (str) - string containing key

RemoveAuthorizedKeys(file_name, keys)

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Removes public SSH keys from an authorized_keys file.

Parameters:

file_name (str) - path to authorized_keys file
keys (list of str) - list of strings containing keys

RemoveAuthorizedKey(file_name, key)

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Removes an SSH public key from an authorized_keys file.

Parameters:

file_name (str) - path to authorized_keys file
key (str) - string containing key

_AddPublicKeyProcessLine(new_uuid, new_key, line_uuid, line_key, found)

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Processes one line of the public key file when adding a key.

This is a sub function that can be called within the _ManipulatePublicKeyFile function. It processes one line of the public key file, checks if this line contains the key to add already and if so, notes the occurrence in the return value.

Parameters:

new_uuid (string) - the node UUID of the node whose key is added
new_key (string) - the SSH key to be added
line_key - the SSH key of the node whose line in the public key file is processed in this function call
found (boolean) - whether or not the (UUID, key) pair of the node whose key is being added was found in the public key file already.
line_uuid (the UUID of the node whose line in the public key file is processed in this function call)

Returns: (boolean, string)

a possibly updated value of found and the processed line

_AddPublicKeyElse(new_uuid, new_key)

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Adds a new SSH key to the key file if it did not exist already.

This is an auxiliary function for _ManipulatePublicKeyFile which is carried out when a new key is added to the public key file and after processing the whole file, we found out that the key does not exist in the file yet but needs to be appended at the end.

Parameters:

new_uuid (string) - the UUID of the node whose key is added
new_key (string) - the SSH key to be added

Returns: string

a new line to be added to the file

_RemovePublicKeyProcessLine(target_uuid, _target_key, line_uuid, line_key, found)

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Processes a line in the public key file when aiming for removing a key.

This is an auxiliary function for _ManipulatePublicKeyFile when we are removing a key from the public key file. This particular function only checks if the current line contains the UUID of the node in question and writes the line to the temporary file otherwise.

Parameters:

target_uuid (string) - UUID of the node whose key is being removed
_target_key (string) - SSH key of the node (not used)
line_uuid (string) - UUID of the node whose line is processed in this call
line_key (string) - SSH key of the nodes whose line is processed in this call
found (boolean) - whether or not the UUID was already found.

Returns: (boolean, string)

a tuple, indicating if the target line was found and the processed line; the line is 'None', if the original line is removed

_RemovePublicKeyElse(target_uuid, _target_key)

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Logs when we tried to remove a key that does not exist.

This is an auxiliary function for _ManipulatePublicKeyFile which is run after we have processed the complete public key file and did not find the key to be removed.

Parameters:

target_uuid (string) - the UUID of the node whose key was supposed to be removed
_target_key (string) - the key of the node which was supposed to be removed (not used)

Returns: string

in this case, always None

_ReplaceNameByUuidProcessLine(node_name, _key, line_identifier, line_key, found, node_uuid=None)

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Replaces a node's name with its UUID on a matching line in the key file.

This is an auxiliary function for _ManipulatePublicKeyFile which processes a line of the ganeti public key file. If the line in question matches the node's name, the name will be replaced by the node's UUID.

Parameters:

node_name (string) - name of the node to be replaced by the UUID
_key (string) - SSH key of the node (not used)
line_identifier (string) - an identifier of a node in a line of the public key file. This can be either a node name or a node UUID, depending on if it got replaced already or not.
line_key (string) - SSH key of the node whose line is processed
found (boolean) - whether or not the line matches the node's name
node_uuid (string) - the node's UUID which will replace the node name

Returns: (boolean, string)

a tuple indicating whether the target line was found and the processed line

_ReplaceNameByUuidElse(node_uuid, node_name, _key)

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Logs a debug message when we try to replace a key that is not there.

This is an implementation of the auxiliary process_else_fn function for the _ManipulatePubKeyFile function when we use it to replace a line in the public key file that is indexed by the node's name instead of the node's UUID.

Parameters:

node_uuid (string) - the node's UUID
node_name (string) - the node's UUID
_key (string (not used)) - the node's SSH key (not used)

Returns: string

in this case, always None

_ParseKeyLine(line, error_fn)

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Parses a line of the public key file.

Parameters:

line (string) - line of the public key file
error_fn (function) - function to process error messages

Returns: tuple (string, string)

a tuple containing the UUID of the node and a string containing the SSH key and possible more parameters for the key

_ManipulatePubKeyFile(target_identifier, target_key, key_file=pathutils.SSH_PUB_KEYS, error_fn=errors.ProgrammerError, process_line_fn=None, process_else_fn=None)

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Manipulates the list of public SSH keys of the cluster.

This is a general function to manipulate the public key file. It needs two auxiliary functions process_line_fn and process_else_fn to work. Generally, the public key file is processed as follows: 1) The function processes each line of the original ganeti public key file, applies the process_line_fn function on it, which returns a possibly manipulated line and an indicator whether the line in question was found. If a line is returned, it is added to a list of lines for later writing to the file. 2) If all lines are processed and the 'found' variable is False, the seconds auxiliary function process_else_fn is called to possibly add more lines to the list of lines. 3) Finally, the list of lines is assembled to a string and written atomically to the public key file, thereby overriding it.

If the public key file does not exist, we create it. This is necessary for a smooth transition after an upgrade.

Parameters:

target_identifier (str) - identifier of the node whose key is added; in most cases this is the node's UUID, but in some it is the node's host name
target_key (str) - string containing a public SSH key (a complete line possibly including more parameters than just the key)
key_file (str) - filename of the file of public node keys (optional parameter for testing)
error_fn (function) - Function that returns an exception, used to customize exception types depending on the calling context
process_line_fn (function) - function to process one line of the public key file
process_else_fn (function) - function to be called if no line of the key file matches the target uuid

AddPublicKey(new_uuid, new_key, key_file=pathutils.SSH_PUB_KEYS, error_fn=errors.ProgrammerError)

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Adds a new key to the list of public keys.

See Also: _ManipulatePubKeyFile for parameter descriptions.

RemovePublicKey(target_uuid, key_file=pathutils.SSH_PUB_KEYS, error_fn=errors.ProgrammerError)

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Removes a key from the list of public keys.

See Also: _ManipulatePubKeyFile for parameter descriptions.

ReplaceNameByUuid(node_uuid, node_name, key_file=pathutils.SSH_PUB_KEYS, error_fn=errors.ProgrammerError)

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Replaces a host name with the node's corresponding UUID.

When a node is added to the cluster, we don't know it's UUID yet. So first its SSH key gets added to the public key file and in a second step, the node's name gets replaced with the node's UUID as soon as we know the UUID.

Parameters:

node_uuid (string) - the node's UUID to replace the node's name
node_name (string) - the node's name to be replaced by the node's UUID

See Also: _ManipulatePubKeyFile for the other parameter descriptions.

OverridePubKeyFile(key_map, key_file=pathutils.SSH_PUB_KEYS)

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Overrides the public key file with a list of given keys.

Parameters:

key_map (dict from str to list of str) - dictionary mapping uuids to lists of SSH keys

QueryPubKeyFile(target_uuids, key_file=pathutils.SSH_PUB_KEYS, error_fn=errors.ProgrammerError)

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Retrieves a map of keys for the requested node UUIDs.

Parameters:

target_uuids (str or list of str) - UUID of the node to retrieve the key for or a list of UUIDs of nodes to retrieve the keys for
key_file (str) - filename of the file of public node keys (optional parameter for testing)
error_fn (function) - Function that returns an exception, used to customize exception types depending on the calling context

Returns: dict mapping strings to list of strings

dictionary mapping node uuids to their ssh keys

InitSSHSetup(key_type, key_bits, error_fn=errors.OpPrereqError, _homedir_fn=None, _suffix="")

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Setup the SSH configuration for the node.

This generates a dsa keypair for root, adds the pub key to the permitted hosts and adds the hostkey to its own known hosts.

Parameters:

key_type - the type of SSH keypair to be generated
key_bits - the key length, in bits, to be used

InitPubKeyFile(master_uuid, key_type, key_file=pathutils.SSH_PUB_KEYS)

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Creates the public key file and adds the master node's SSH key.

Parameters:

master_uuid (str) - the master node's UUID
key_type (one of constants.SSHK_ALL) - the type of ssh key to be used
key_file (str) - name of the file containing the public keys

_EnsureCorrectGanetiVersion(cmd)

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Ensured the correct Ganeti version before running a command via SSH.

Before a command is run on a node via SSH, it makes sense in some situations to ensure that this node is indeed running the correct version of Ganeti like the rest of the cluster.

Parameters:

cmd (string) - string

Returns: list of strings

a list of commands with the newly added ones at the beginning

RunSshCmdWithStdin(cluster_name, node, basecmd, port, data, debug=False, verbose=False, use_cluster_key=False, ask_key=False, strict_host_check=False, ensure_version=False)

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Runs a command on a remote machine via SSH and provides input in stdin.

Parameters:

cluster_name (string) - Cluster name
node (string) - Node name
basecmd (string) - Base command (path on the remote machine)
port (int) - The SSH port of the remote machine or None for the default
data - JSON-serializable input data for script (passed to stdin)
debug (bool) - Enable debug output
verbose (bool) - Enable verbose output
use_cluster_key (bool) - See ssh.SshRunner.BuildCmd
ask_key (bool) - See ssh.SshRunner.BuildCmd
strict_host_check (bool) - See ssh.SshRunner.BuildCmd

ReadRemoteSshPubKeys(pub_key_file, node, cluster_name, port, ask_key, strict_host_check)

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Fetches a public SSH key from a node via SSH.

Parameters:

pub_key_file (string) - a tuple consisting of the file name of the public DSA key

DetermineKeyBits(key_type, key_bits, old_key_type, old_key_bits)

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Checks the key bits to be used for a given key type, or provides defaults.

Parameters:

key_type (one of constants.SSHK_ALL) - The key type to use.
key_bits (positive int or None) - The number of bits to use, if supplied by user.
old_key_type (one of constants.SSHK_ALL or None) - The previously used key type, if any.
old_key_bits (positive int or None) - The previously used number of bits, if any.

Returns: positive int

The number of bits to use.

Variables Details

[hide private]

KeyBitInfo

Value:

namedtuple('KeyBitInfo', ['default', 'validation_fn'])

SSH_KEY_VALID_BITS

Value:

{constants.SSHK_DSA: KeyBitInfo(1024, lambda b: b== 1024), constants.S
SHK_RSA: KeyBitInfo(2048, lambda b: b >= 768), constants.SSHK_ECDSA: K
eyBitInfo(384, lambda b: b in [256, 384, 521]),}