README
¶
zrepl
zrepl is a one-stop ZFS backup & replication solution.
User Documentation
User Documentation can be found at zrepl.github.io.
Bug Reports
- If the issue is reproducible, enable debug logging, reproduce and capture the log.
- Open an issue on GitHub, with logs pasted as GitHub gists / inline.
Feature Requests
- Does you feature request require default values / some kind of configuration? If so, think of an expressive configuration example.
- Think of at least one use case that generalizes from your concrete application.
- Open an issue on GitHub with example conf & use case attached.
The above does not apply if you already implemented everything. Check out the Coding Workflow section below for details.
Package Maintainer Information
- Follow the steps in
docs/installation.rst -> Compiling from Sourceand read the Makefile / shell scripts used in this process. - Make sure your distro is compatible with the paths in
docs/installation.rst. - Ship a default config that adheres to your distro's
hierand logging system. - Ship a service manager file and please try to upstream it to this repository.
dist/systemdcontains a Systemd unit template.
- Ship other material provided in
./dist, e.g. in/usr/share/zrepl/. - Use
make release ZREPL_VERSION='mydistro-1.2.3_1'- Your distro's name and any versioning supplemental to zrepl's (e.g. package revision) should be in this string
- Make sure you are informed about new zrepl versions, e.g. by subscribing to GitHub's release RSS feed.
Developer Documentation
zrepl is written in Go and uses dep to manage dependencies.
The documentation is written in ReStructured Text using the Sphinx framework.
To get started, run ./lazy.sh devsetup to easily install build dependencies and read docs/installation.rst -> Compiling from Source.
Overall Architecture
The application architecture is documented as part of the user docs in the Implementation section (docs/content/impl).
Make sure to develop an understanding how zrepl is typically used by studying the user docs first.
Project Structure
├── artifacts # build artifcats generate by make
├── cli # wrapper around CLI package cobra
├── client # all subcommands that are not `daemon`
├── config # config data types (=> package yaml-config)
│ └── samples
├── daemon # the implementation of `zrepl daemon` subcommand
│ ├── filters
│ ├── job # job implementations
│ ├── logging # logging outlets + formatters
│ ├── nethelpers
│ ├── prometheus
│ ├── pruner # pruner implementation
│ ├── snapper # snapshotter implementation
├── docs # sphinx-based documentation
├── dist # supplemental material for users & package maintainers
│ ├── **/*.rst # documentation in reStructuredText
│ ├── sphinxconf
│ │ └── conf.py # sphinx config (see commit 445a280 why its not in docs/)
│ ├── requirements.txt # pip3 requirements to build documentation
│ ├── publish.sh # shell script for automated rendering & deploy to zrepl.github.io repo
│ └── public_git # checkout of zrepl.github.io managed by above shell script
├── endpoint # implementation of replication endpoints (=> package replication)
├── logger # our own logger package
├── pruning # pruning rules (the logic, not the actual execution)
│ └── retentiongrid
├── replication
│ ├── driver # the driver of the replication logic (status reporting, error handling)
│ ├── logic # planning & executing replication steps via rpc
| | └── pdu # the generated gRPC & protobuf code used in replication (and endpoints)
│ └── report # the JSON-serializable report datastructures exposed to the client
├── rpc # the hybrid gRPC + ./dataconn RPC client: connects to a remote replication.Endpoint
│ ├── dataconn # Bulk data-transfer RPC protocol
│ ├── grpcclientidentity # adaptor to inject package transport's 'client identity' concept into gRPC contexts
│ ├── netadaptor # adaptor to convert a package transport's Connecter and Listener into net.* primitives
│ ├── transportmux # TCP connecter and listener used to split control & data traffic
│ └── versionhandshake # replication protocol version handshake perfomed on newly established connections
├── tlsconf # abstraction for Go TLS server + client config
├── transport # transports implementation
│ ├── fromconfig
│ ├── local
│ ├── ssh
│ ├── tcp
│ └── tls
├── util
├── vendor # managed by dep
├── version # abstraction for versions (filled during build by Makefile)
└── zfs # zfs(8) wrappers
Coding Workflow
- Open an issue when starting to hack on a new feature
- Commits should reference the issue they are related to
- Docs improvements not documenting new features do not require an issue.
Breaking Changes
Backward-incompatible changes must be documented in the git commit message and are listed in docs/changelog.rst.
- Config-breaking changes must contain a line
BREAK CONFIGin the commit message - Other breaking changes must contain a line
BREAKin the commit message
Glossary & Naming Inconsistencies
In ZFS, dataset refers to the objects filesystem, ZVOL and snapshot.
However, we need a word for filesystem & ZVOL but not a snapshot, bookmark, etc.
Toward the user, the following terminology is used:
- filesystem: a ZFS filesystem or a ZVOL
- filesystem version: a ZFS snapshot or a bookmark
Sadly, the zrepl implementation is inconsistent in its use of these words: variables and types are often named dataset when they in fact refer to a filesystem.
There will not be a big refactoring (an attempt was made, but it's destroying too much history without much gain).
However, new contributions & patches should fix naming without further notice in the commit message.
Documentation
Source Files
Directories
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| Path | Synopsis |
|---|---|
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This package is a pseudo-user of build-time dependencies for zrepl, mostly for various code-generation tools.
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This package is a pseudo-user of build-time dependencies for zrepl, mostly for various code-generation tools. |
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Package endpoint implements replication endpoints for use with package replication.
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Package endpoint implements replication endpoints for use with package replication. |
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Package replication implements replication of filesystems with existing versions (snapshots) from a sender to a receiver.
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Package replication implements replication of filesystems with existing versions (snapshots) from a sender to a receiver. |
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Package rpc implements zrepl daemon-to-daemon RPC protocol on top of a transport provided by package transport.
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Package rpc implements zrepl daemon-to-daemon RPC protocol on top of a transport provided by package transport. |
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dataconn/heartbeatconn/integration_test_variablereceiverate
This integration test exercises the behavior of heartbeatconn where the server is slow at handling the data received over the connection.
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This integration test exercises the behavior of heartbeatconn where the server is slow at handling the data received over the connection. |
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dataconn/microbenchmark
microbenchmark to manually test rpc/dataconn perforamnce With stdin / stdout on client and server, simulating zfs send|recv piping ./microbenchmark -appmode server | pv -r > /dev/null ./microbenchmark -appmode client -direction recv < /dev/zero Without the overhead of pipes (just protocol perforamnce, mostly useful with perf bc no bw measurement) ./microbenchmark -appmode client -direction recv -devnoopWriter -devnoopReader ./microbenchmark -appmode server -devnoopReader -devnoopWriter
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microbenchmark to manually test rpc/dataconn perforamnce With stdin / stdout on client and server, simulating zfs send|recv piping ./microbenchmark -appmode server | pv -r > /dev/null ./microbenchmark -appmode client -direction recv < /dev/zero Without the overhead of pipes (just protocol perforamnce, mostly useful with perf bc no bw measurement) ./microbenchmark -appmode client -direction recv -devnoopWriter -devnoopReader ./microbenchmark -appmode server -devnoopReader -devnoopWriter |
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dataconn/timeoutconn
package timeoutconn wraps a Wire to provide idle timeouts based on Set{Read,Write}Deadline.
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package timeoutconn wraps a Wire to provide idle timeouts based on Set{Read,Write}Deadline. |
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dataconn/timeoutconn/internal/wireevaluator
a tool to test whether a given transport implements the timeoutconn.Wire interface
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a tool to test whether a given transport implements the timeoutconn.Wire interface |
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grpcclientidentity
Package grpcclientidentity makes the client identity provided by github.com/zrepl/zrepl/daemon/transport/serve.{AuthenticatedListener,AuthConn} available to gRPC service handlers.
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Package grpcclientidentity makes the client identity provided by github.com/zrepl/zrepl/daemon/transport/serve.{AuthenticatedListener,AuthConn} available to gRPC service handlers. |
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grpcclientidentity/example
This package demonstrates how the grpcclientidentity package can be used to set up a gRPC greeter service.
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This package demonstrates how the grpcclientidentity package can be used to set up a gRPC greeter service. |
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grpcclientidentity/grpchelper
Package grpchelper wraps the adaptors implemented by package grpcclientidentity into a less flexible API which, however, ensures that the individual adaptor primitive's expectations are met and hence do not panic.
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Package grpchelper wraps the adaptors implemented by package grpcclientidentity into a less flexible API which, however, ensures that the individual adaptor primitive's expectations are met and hence do not panic. |
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netadaptor
Package netadaptor implements an adaptor from transport.AuthenticatedListener to net.Listener.
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Package netadaptor implements an adaptor from transport.AuthenticatedListener to net.Listener. |
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transportmux
Package transportmux wraps a transport.{Connecter,AuthenticatedListener} to distinguish different connection types based on a label sent from client to server on connection establishment.
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Package transportmux wraps a transport.{Connecter,AuthenticatedListener} to distinguish different connection types based on a label sent from client to server on connection establishment. |
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versionhandshake
Package versionhandshake wraps a transport.{Connecter,AuthenticatedListener} to add an exchange of protocol version information on connection establishment.
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Package versionhandshake wraps a transport.{Connecter,AuthenticatedListener} to add an exchange of protocol version information on connection establishment. |
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Package transport defines a common interface for network connections that have an associated client identity.
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Package transport defines a common interface for network connections that have an associated client identity. |
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fromconfig
Package fromconfig instantiates transports based on zrepl config structures (see package config).
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Package fromconfig instantiates transports based on zrepl config structures (see package config). |
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util
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chainlock
package chainlock implements a mutex whose Lock and Unlock methods return the lock itself, to enable chaining.
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package chainlock implements a mutex whose Lock and Unlock methods return the lock itself, to enable chaining. |
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devnoop
package devnoop provides an io.ReadWriteCloser that never errors and always reports reads / writes to / from buffers as complete.
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package devnoop provides an io.ReadWriteCloser that never errors and always reports reads / writes to / from buffers as complete. |
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