CedarBackup3.extend.postgresql

Provides an extension to back up PostgreSQL databases.

This is a Cedar Backup extension used to back up PostgreSQL databases via the Cedar Backup command line. It requires a new configurations section <postgresql> and is intended to be run either immediately before or immediately after the standard collect action. Aside from its own configuration, it requires the options and collect configuration sections in the standard Cedar Backup configuration file.

The backup is done via the pg_dump or pg_dumpall commands included with the PostgreSQL product. Output can be compressed using gzip or bzip2. Administrators can configure the extension either to back up all databases or to back up only specific databases. The extension assumes that the current user has passwordless access to the database since there is no easy way to pass a password to the pg_dump client. This can be accomplished using appropriate voodoo in the pg_hda.conf file.

Note that this code always produces a full backup. There is currently no facility for making incremental backups.

You should always make /etc/cback3.conf unreadble to non-root users once you place postgresql configuration into it, since postgresql configuration will contain information about available PostgreSQL databases and usernames.

Use of this extension may expose usernames in the process listing (via ps) when the backup is running if the username is specified in the configuration.

author

Kenneth J. Pronovici <pronovic@ieee.org>

author

Antoine Beaupre <anarcat@koumbit.org>

Module Contents

CedarBackup3.extend.postgresql.logger

CedarBackup3.extend.postgresql.POSTGRESQLDUMP_COMMAND = ['pg_dump']

CedarBackup3.extend.postgresql.POSTGRESQLDUMPALL_COMMAND = ['pg_dumpall']

class CedarBackup3.extend.postgresql.PostgresqlConfig(user=None, compressMode=None, all=None, databases=None)

Bases: object

Class representing PostgreSQL configuration.

The PostgreSQL configuration information is used for backing up PostgreSQL databases.

The following restrictions exist on data in this class:

• The compress mode must be one of the values in VALID_COMPRESS_MODES.

• The ‘all’ flag must be ‘Y’ if no databases are defined.

• The ‘all’ flag must be ‘N’ if any databases are defined.

• Any values in the databases list must be strings.

user

compressMode

all

databases

__repr__()

Official string representation for class instance.

__str__()

Informal string representation for class instance.

__eq__(other)

Equals operator, iplemented in terms of original Python 2 compare operator.

__lt__(other)

Less-than operator, iplemented in terms of original Python 2 compare operator.

__gt__(other)

Greater-than operator, iplemented in terms of original Python 2 compare operator.

__cmp__(other)

Original Python 2 comparison operator. :param other: Other object to compare to

Returns

-1/0/1 depending on whether self is <, = or > other

class CedarBackup3.extend.postgresql.LocalConfig(xmlData=None, xmlPath=None, validate=True)

Bases: object

Class representing this extension’s configuration document.

This is not a general-purpose configuration object like the main Cedar Backup configuration object. Instead, it just knows how to parse and emit PostgreSQL-specific configuration values. Third parties who need to read and write configuration related to this extension should access it through the constructor, validate and addConfig methods.

Note: Lists within this class are “unordered” for equality comparisons.

postgresql

__repr__()

Official string representation for class instance.

__str__()

Informal string representation for class instance.

__eq__(other)

Equals operator, iplemented in terms of original Python 2 compare operator.

__lt__(other)

Less-than operator, iplemented in terms of original Python 2 compare operator.

__gt__(other)

Greater-than operator, iplemented in terms of original Python 2 compare operator.

__cmp__(other)

Original Python 2 comparison operator. Lists within this class are “unordered” for equality comparisons. :param other: Other object to compare to

Returns

-1/0/1 depending on whether self is <, = or > other

validate()

Validates configuration represented by the object.

The compress mode must be filled in. Then, if the ‘all’ flag is set, no databases are allowed, and if the ‘all’ flag is not set, at least one database is required.

Raises

ValueError – If one of the validations fails

addConfig(xmlDom, parentNode)

Adds a <postgresql> configuration section as the next child of a parent.

Third parties should use this function to write configuration related to this extension.

We add the following fields to the document:

user           //cb_config/postgresql/user
compressMode   //cb_config/postgresql/compress_mode
all            //cb_config/postgresql/all

We also add groups of the following items, one list element per item:

database       //cb_config/postgresql/database

Parameters

• xmlDom – DOM tree as from impl.createDocument()

• parentNode – Parent that the section should be appended to

CedarBackup3.extend.postgresql.executeAction(configPath, options, config)

Executes the PostgreSQL backup action.

Parameters

• configPath (String representing a path on disk) – Path to configuration file on disk

• options (Options object) – Program command-line options

• config (Config object) – Program configuration

Raises

• ValueError – Under many generic error conditions

• IOError – If a backup could not be written for some reason

CedarBackup3.extend.postgresql.backupDatabase(user, backupFile, database=None)

Backs up an individual PostgreSQL database, or all databases.

This function backs up either a named local PostgreSQL database or all local PostgreSQL databases, using the passed in user for connectivity. This is always a full backup. There is no facility for incremental backups.

The backup data will be written into the passed-in back file. Normally, this would be an object as returned from open, but it is possible to use something like a GzipFile to write compressed output. The caller is responsible for closing the passed-in backup file.

Note: Typically, you would use the root user to back up all databases.

Parameters

• user (String representing PostgreSQL username) – User to use for connecting to the database

• backupFile (Python file object as from open or file) – File use for writing backup

• database (String representing database name, or None for all databases) – Name of the database to be backed up

Raises

• ValueError – If some value is missing or invalid

• IOError – If there is a problem executing the PostgreSQL dump