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Language: Python
Dump and restore objects between a ZODB and a serialized file system structure
This package provides tools to serialize Zope objects and store them in a file system structure as well as to restore Zope objects from this structure.
Some features require that the file system structure is governed by git as
version control system.
Ján Jockusch jan.jockusch@perfact.de
Viktor Dick viktor.dick@perfact.de
git clone https://github.com/perfact/zodbsync.git
In general, the PyPi access token is personalized, so publishing can only be done by one person (currently Viktor). Scratch tokens are stored in the PerFact vault so this can be changed in the case of an emergency.
See https://packaging.python.org/en/latest/tutorials/packaging-projects/.
The username __token__ and the password from pypi needs to be stored to
~/.pypirc. Then:
virtualenv venv
venv/bin/pip install build twine
venv/bin/python -m build
venv/bin/twine upload dist/*
The package should be installed using pip in the same virt-env as zope, p.e.
zope/bin/pip install perfact-zodbsync
On PerFact systems, it should automatically be pulled by the requirements.txt
of the package perfact-dbutils-zope4 and included there.
On newer PerFact Zope4 installations, install test branch via, e.g. for
development/testing purposes
sudo -H /usr/share/perfact/zope4/bin/pip install git+https://github.com/perfact/zodbsync@test --upgrade
If the setuptools version used by the Zope virtualenv is too old (for
example, on Ubuntu 20.04 or 22.04), you need to build the package in a separate
virtualenv using a new setuptools version and then install it:
virtualenv build-venv
build-venv/bin/pip install 'setuptools>=61.2' build
build-venv/bin/python -m build
sudo -H /usr/share/perfact/zope4/bin/pip install dist/$(ls -t dist/*.tar.gz | head -n 1)
Note that executing the tests requires ODBC C headers to be installed. On
Debian-like systems, install the package unixodbc-dev.
Use the config.py as a starting point for your configuration. At the moment,
it is not automatically installed. The canonical path for the configuration is
/etc/perfact/modsync/zodb.py, so if you do not want to supply the path to
the configuration when calling the scripts, copy the configuration file there.
The most important settings are:
Set conf_path or wsgi_conf_path to the zope.conf of your Zope instance.
If it is a standalone instance exclusively accessing its ZODB, it must be
powered down if used by zodbsync. So usually it is advisable that it is
configured to connect to a ZEO server.
The two options are present due to a no longer relevant difference between
ZServer and WSGI instance handling and can now be used interchangeably.
Inside this folder (actually, in a subfolder named __root__), the serialized
objects are placed.
The name of a user that must be defined in the top-level UserFolder
(acl_users) and which has Manager permissions. Transactions that are used to
upload objects to the ZODB are done by this user.
This user is considered to be the default owner of objects if no other information is stored in the object.
Can be combined with default_owner to enforce a specific owner for objects
in the ZODB.
The path to the location of the Data.fs file. This is needed for zodbsync watch.
Path to a script that is executed after a successful (non-recursive) playback,
including indirect calls from reset or pick. If the script exists, it is
called and fed the list of changed objects in a JSON format.
Path to script which is called to define the phases of playback to be
executed, Recieves a json dictionary in the form of {"paths": [...]}
and should output a json dictionary in the form of
[
{
"paths": [...],
"cmd": [...]
},
{
"paths": [...],
}
]Path to folder on the filesystem that contains layer definitions. See below.
The executable zodbsync provides several subcommands
The record subcommand is used to record objects from the ZODB to the file
system.
Each object is mapped to a folder that contains at least the file
__meta__ which holds the meta data of the object (properties, permissions etc.).
If the object contains other objects (like Folders), they are represented as
subfolders. If the object has some sort of source (like Page Templates, DTML Methods etc.), it is stored in an additional file. The filename suffix is
taken from the object type and possibly content type, while the base is either
__source__ or __source-utf8__
Only a specific list of object types is supported by zodbsync. Objects whose
type is not yet supported are created with a minimal __meta__ file,
containing only the title, type and an unsupported marker.
An additional option
--commit allows to create a git commit after the recording, sending a
summary mail containing all changed files to an address specified in the
configuration. This can be used as automated reminder fallback if changes are
not commited timely.
If zodbsync record is called with the --lasttxn option, it tries to do an
incremental recording, reading all transactions that occured since the last
call (the transaction ID is stored in a file __last_txn__ in the repository).
The paths to be recorded are extracted from the transaction note, which works
well if editing an object in the management interface of Zope, but not
necessarily if an object is changed from within a script, if it is transferred
by the ZSyncer or if objects are cut and pasted (in the latter case, only the
target of the move operation is recognized).
This subcommand starts a process that aims to bypass the shortcomings of
zodbsync record --lasttxn. The process stays alive and builds an object tree
of all objects in the ZODB. Each time it wakes up, it scans for new
transactions, opens the Data.FS directly (in read-only mode) to obtain all
affected object IDs, updates its object tree and uses it to obtain the physical
paths of all affected objects. After finishing, it sleeps for 10 seconds before
waking again. This should provide an almost live recording that does not miss
any changes.
The opposite operation to record is playback, which is able to create and
modify objects in the ZODB from a file system structure as it is created by
record.
By default, playback recurses into the subtree below a given
path, removing any superfluous objects and updating existing objects so they
match their file system representation. An exception are objects that are
marked as unsupported, which are ignored if found in the ZODB. If only a
given object itself should be updated (properties, security settings etc.),
--no-recurse can be used.
This command requires the base directory to be a git repository and provides a
wrapper for several git commands. It executes the given command, reads the
objects changed between the old and new HEAD and plays them back. Any
unstaged changes are stashed away and restored afterwards. The operation is
aborted and rolled back if it results in a broken state (an interrupted
merge, rebase, cherry-pick etc.) or if there is an overlap between the
unstaged and the changed files.
This allows commands like the following:
zodbsync exec "git cherry-pick COMMIT"
zodbsync exec "git checkout otherbranch"
zodbsync exec "git reset --hard COMMIT"
zodbsync exec "git revert COMMIT"
Shorthand for zodbsync exec "git reset --hard COMMIT"
Wrapper for git checkout with some of its functionality.
As a special case of exec, this wraps git cherry-pick and takes git commits
to be applied as arguments.
This is useful if some development has been done in a branch or on a remote
system that has to be deployed to the current system. It then becomes possible
to do something like
git fetch origin
zodbsync pick origin/master
to pull the latest commit, apply it to the current repository and upload the
affected paths to the Data.FS. It can also be used to pick multiple commits.
Its argument --grep allows, for example, to pull all commits where the commit
message starts with T12345:
zodbsync pick --grep="^T12345" source/master
Similarly, --since and --until can be used to limit commits - see the git log documentation.
Commit ranges in the form of COMMIT1..COMMIT2 can also be picked, but be
aware that there is no check that the commit range is actually a straight
forward succession - internally, git log is used and therefore any commits
that are reachable from COMMIT2 but not from COMMIT1 are picked. In
practice, choosing commits that are not directly connected will result in some
commit not being able to be picked due to conflicts and a rollback of the
operation.
upload expects the base directory to be a git repository and provides a tool
to upload JS and CSS libraries into the Data.fs. This is achieved by converting
these files into files and directories understood by playback and placing them
in the specified directory inside of base_dir.
Example to upload bootstrap:
zodbsync upload /tmp/bootstrap lib/bootstrap
This subcommand is deprecated because external libraries should not be put into the Data.FS. Instead, it is more efficient if they are served directly from the file system.
If some combination of git and zodbsync operations is not yet covered by a
wrapper subcommand, it is possible to use zodbsync with-lock to execute a
series of commands while still making sure that no other similar operation
interferes. Any zodbsync command used as part of this must then use the
option --no-lock. For example:
zodbsync with-lock "git rebase origin/main && zodbsync --no-lock playback /"
Although this particular example can now be better achieved with zodbsync exec.
With version 4.3.2, the formatting of meta files was changed to become more
diff-friendly, placing, for example, lists of roles for a specific permission
onto one line each. When transferring commits from a system that used the old
recording to one that uses the new one, zodbsync reformat can be used to
rewrite commits of the old to the new version.
Use a separate repository clone, check out the starting point and pick the
commits that used the old formatting on top of it. Executing reformat will
add a commit that reformats the complete repository after the starting point,
followed by rewritten commits that correspond to the original ones, but using
the new formatting. Finally, pick these commits onto the target system.
Detailed steps:
find the commit ID of the first commit you want to reformat,
this ID will be referred to as START
from the source branch or system, check out the commit before START
and create a work branch
git checkout START~git checkout -b <work-branch>pick the commits to be reformatted into the work branch
git cherry-pick -Xno-renames <commit-ids ...>run reformat: this will create a commit between START~ and START
containing the reformatting of the entire repo from old to new format and
applies the following commits as if they had been committed using the new
format
zodbsync reformat START~if the project also contains commits made after the format change,
cherry-pick them into the work branch now
push the work branch to the target system and zodbsync pick the commits
(except the zodbsync reformat commit)
Hint: This requires git in version 2.22 or above.
Since version 23.1.0, zodbsync has gained the possibility to handle multiple
file system source trees that each contribute a separate layer to the objects
in the Data.FS. Layer handling was reworked for 23.4.0 and the following
describes the new handling.
The configuration option layers points to a folder on the file system that
contains separate configuration files or symlinks that may be contributed by
different layer packages. These are read alphabetically from the bottom-most to
the top-most layer and provide the following options:
A path where the layer is placed. This needs to be owned by the user that
executes zodbsync. It will be initialized as a git repository if it is not
already one.
This path provides the objects of a layer, possibly read-only to the user
executing zodbsync and provided by a Debian package or similar. Must be a
directory containing a __root__ subdirectory or __root__.tar* file.
Additionally, it can contain further folders or compressed files that will also
be copied over or unpacked to the workdir.
An implicit fallback layer is added at the top where workdir is set to the
base_dir provided in the main config for compatibility with a non-layered
setup and without a source.
The representation rules for objects in a multi-layer setup are as follows:
__meta__ file
for it.__frozen__ file, both the folder and
any subobjects from any layer below this are ignored - the layer is expected
to fully replicate the intended state of the folder and anything below it.__deleted__, the object is supposed to be
deleted even if it is defined in some layer below. It must not also contain a
meta or source file or any subdirectories. It may additionally contain a
__frozen__ file, which makes a difference if the object reappears and
controls if the lower layers are considered or not.The following subcommands for zodbsync provide layer handling:
Initialize all given layers by initializing the workdir and
copying/extracting all objects there. This does not play back anything into
the Data.FS. It is intended for the use case where code that was previously
part of one layer (maybe the fallback layer) is now to be provided by a
separate layer. Afterwards, a record call can be used to clear up the
duplicates present in both layers.
For each given layer, any unstaged changes in the workdir are committed and
the layer content is reset to that found in the source. This is used to
update a layer to a newer version. Note that any changes done directly in the
layer since the last update are overwritten by this - they can still be found
in the git history in the workdir, but the working directory and the
resulting Data.FS content are reset. It is therefore possible to pre-apply
changes that will be part of the next release, but if there is a change that is
not yet merged upstream, the layer should not be updated until it is.
This package replaces similar functionality that was previously found in
python-perfact and perfact-dbutils-zope2. For backwards compatibility,
those packages were changed so the corresponding calls try to import
perfact.zodbsync and use the functionality there, falling back to the
previous implementation if that fails. Corresponding deprecation warnings are
included.
Previous versions contained the scripts perfact-zoperecord and
perfact-zopeplayback instead of zodbsync. For compatibility with systems
automatically calling perfact-zoperecord, it is still included but only
providing the bare functionality:
perfact-zoperecord (corresponds to zodbsync record --commit /)perfact-zoperecord --lasttxn (corresponds to zodbsync record --lasttxn,
but including a call to perfact-dbrecord if a databases key is defined
in the configuration)Zope allows External Methods to be present in the ZODB even if the
corresponding modules are no longer present as extensions. It does not,
however, allow saving such an object. This gives errors if object trees
containing broken External Methods are recorded and played back. The same
holds for Z SQL Methods which have class_name and class_file set to a no
longer existing extension.
Since 22.2.5 a more recent version ( >= 3.26.0 ) of tox is required
in order to build the test environment from pyproject.toml instead of
setup.py. Do NOT get fooled by errors like ERROR: No setup.py file found.,
just upgrade tox to latest version and retry.
To allow developing multiple layers on the same development system, record
should be changed to follow the following rules:
workdir of the layer that
defines its parent.__frozen__ marker.All commands that allow to apply changes, like pick and reset, should be
able to work on all layers' workdirs, not only on the fallback layer.
Some more commands are then needed for the following layer use cases:
__frozen__ marker, reset the
unstaged changes in the layer that wrongfully got the changes, and
record.__frozen__ markers where
necessary. Remove all superfluous files from the original layer (which now
becomes the fallback layer) and initialize the added layers.