warppipe

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 Go to latest Published: May 29, 2020 License: MIT Imports: 12 Imported by: 0

README

warp-pipe

NOTE: NOT FOR PRODUCTION USE, THIS IS A WORK IN PROGRESS

warp-pipe is a simple CDC tool for Postgres.

How does it work

warp-pipe supports two modes, depending on the version and configuration of Postgres that you are running:

Logical Replication (LR)
Requirements
  • Postgres >= 9.5
  • wal2json
  • Logical replication enabled (via postgresql.conf)

You need to set up at least two parameters at postgresql.conf:

// postgresql.conf (changes require restart)
wal_level = logical
max_replication_slots = 1

In LR mode, warp-pipe will connect to a replication slot on your database using the wal2json output plugin, and emit Changesets via channel.

NOTE: You must set the appropriate REPLICA IDENTITY on your tables if you wish to expose old values in changesets. To learn more, see replica identity.

Audit
Requirements
  • Postgres >= 9.4

In audit mode, warp-pipe creates a new schema (warp_pipe) with a changesets tables in your database to track modifications on your schema's tables. A trigger is registered with all configured tables to notify (via NOTIFY/LISTEN) when there are new changes to be read.

Installation

Install the warp-pipe library with:

go get github.com/perangel/warp-pipe

Install the library and daemon with:

go get github.com/perangel/warp-pipe/...

Demo

The demo shows how data in a Source DB can be accessed as a stream and used to sync to a Target DB.

  1. Creates two databases in Docker.
  2. Sets up a schema on the Source DB.
  3. Sets up a schema on the Target DB.
  4. Runs warp-pipe setup-db on the Source DB.
  5. Pauses to allow the user to load a front-end web application which loads Warp Pipe Changesets via websockets.
  6. Adds data to the Source DB.
  7. Runs axon to sync data from the Source to Target.

Run:

make demo
make demo-clean
Usage
Run a warp-pipe and stream changes from a Postgres database.

Usage:
  warp-pipe [flags]
  warp-pipe [command]

Available Commands:
  help        Help about any command
  setup-db    Setup the source database
  teardown-db Teardown the `warp_pipe` schema

Flags:
      --start-from-lsn int         stream all changes starting from the provided LSN (default -1)
      --start-from-id int          stream all changes starting from the provided changeset ID (default -1)
      --start-from-ts int          stream all changes starting from the provided timestamp (default -1)
  -M, --replication-mode string    replication mode (default "lr")
  -i, --ignore-tables strings      tables to ignore during replication
  -w, --whitelist-tables strings   tables to include during replication
  -H, --db-host string             database host
  -d, --db-name string             database name
  -P, --db-pass string             database password
  -p, --db-port int                database port
  -U, --db-user string             database user
  -L, --log-level string           log level (default "info")
  -h, --help                       help for warp-pipe

Use "warp-pipe [command] --help" for more information about a command.
Configuration
Flag Environment Variable Description Mode
--start-from-lsn START_FROM_LSN Sets the logical sequence number from which to start logical replication lr
--start-from-id START_FROM_ID Sets the changeset ID from which to start relaying changesets audit
--start-from-ts START_FROM_TIMESTAMP Sets the timestamp from which to start replaying changesets audit
-M, --replication-mode REPLICATION_MODE Sets the replication mode to one of audit or lr (logical replication) (see: requirements) *
-i, --ignore-tables IGNORE_TABLES Specify tables to exclude from replication. *
-w, --whitelist-tables WHITELIST_TABLES Specify tables to include during replication. *
-H, --db-host DB_HOST The database host. *
-d, --db-name DB_NAME The database name. *
-P, --db-pass DB_PASS The database password. *
-p, --db-port DB_PORT The database port. *
-U, --db-user DB_USER The database user. *
-L, --log-level LOG_LEVEL Sets the logging level *

Additional Reading

Documentation

Index

Constants

This section is empty.

Variables

This section is empty.

Functions

func ParseLogLevel 

func ParseLogLevel(level string) (logrus.Level, error)

ParseLogLevel parses a log level string and returns a logrus.Level.

Types

type Changeset 

type Changeset struct {
	Kind      ChangesetKind      `json:"kind"`
	Schema    string             `json:"schema"`
	Table     string             `json:"table"`
	Timestamp time.Time          `json:"timestamp"`
	NewValues []*ChangesetColumn `json:"new_values"`
	OldValues []*ChangesetColumn `json:"old_values"`
}

Changeset represents a changeset for a record on a Postgres table.

func (*Changeset) GetNewColumnValue 

func (c *Changeset) GetNewColumnValue(column string) (interface{}, bool)

GetNewColumnValue returns the current value for a column and a bool denoting whether a new value is present in the changeset.

func (*Changeset) GetPreviousColumnValue 

func (c *Changeset) GetPreviousColumnValue(column string) (interface{}, bool)

GetPreviousColumnValue returns the previous value for a column and a bool denoting whether an old value is present in the changeset.

func (*Changeset) String 

func (c *Changeset) String() string

String implements Stringer to create a useful string representation of a Changeset.

type ChangesetColumn 

type ChangesetColumn struct {
	Column string      `json:"column"`
	Value  interface{} `json:"value"`
	Type   string      `json:"type"`
}

ChangesetColumn represents a type and value for a column in a changeset.

type ChangesetKind 

type ChangesetKind string

ChangesetKind is the type for changeset kinds 

const (
	ChangesetKindInsert ChangesetKind = "insert"
	ChangesetKindUpdate ChangesetKind = "update"
	ChangesetKindDelete ChangesetKind = "delete"
)

ChangsetKind constants

func ParseChangesetKind 

func ParseChangesetKind(kind string) ChangesetKind

ParseChangesetKind parses a changeset kind from a string.

type Config 

type Config struct {
	// Database connection settings.
	Database DBConfig

	// If defined, warppipe will only emit changes for the specified tables.
	WhitelistTables []string `envconfig:"WHITELIST_TABLES"`

	// If set, warppipe will suppress changes for any specified tables.
	// Note: This setting takes precedent over the whitelisted tables.
	IgnoreTables []string `envconfig:"IGNORE_TABLES"`

	// Replication mode may be either `lr` (logical replication) or `audit`.
	ReplicationMode string `envconfig:"REPLICATION_MODE" default:"lr"`

	// Specifies the replication slot name to be used. (LR mode only)
	ReplicationSlotName string `envconfig:"REPLICATION_SLOT_NAME"`

	// Start replication from the specified logical sequence number. (LR mode only)
	StartFromLSN uint64 `envconfig:"START_FROM_LSN"`

	// Start replication from the specified changeset ID. (Audit mode only)
	StartFromID int64 `envconfig:"START_FROM_ID"`

	// Start replication from the specified changeset timestamp. (Audit mode only)
	StartFromTimestamp int64 `envconfig:"START_FROM_TIMESTAMP"`

	// Sets the log level
	LogLevel string `envconfig:"LOG_LEVEL" default:"info"`
}

Config represents the warp pipe configuration settings.

func NewConfigFromEnv 

func NewConfigFromEnv() (*Config, error)

NewConfigFromEnv returns a new Config initialized with values read from the environment.

type DBConfig 

type DBConfig struct {
	Host     string `envconfig:"DB_HOST"`
	Port     int    `envconfig:"DB_PORT"`
	User     string `envconfig:"DB_USER"`
	Password string `envconfig:"DB_PASS"`
	Database string `envconfig:"DB_NAME"`
	Schema   string `envconfig:"DB_SCHEMA"`
}

DBConfig represents the database configuration settings.

type LROption 

type LROption func(*LogicalReplicationListener)

LROption is a LogicalReplicationListener option function

func HeartbeatInterval 

func HeartbeatInterval(seconds int) LROption

HeartbeatInterval is an option for setting the connection heartbeat interval.

func ReplSlotName 

func ReplSlotName(name string) LROption

ReplSlotName is an option for setting the replication slot name.

func StartFromLSN 

func StartFromLSN(lsn uint64) LROption

StartFromLSN is an option for setting the logical sequence number to start from.

type Listener 

type Listener interface {
	Dial(*pgx.ConnConfig) error
	ListenForChanges(context.Context) (chan *Changeset, chan error)
	Close() error
}

Listener is an interface for implementing a changeset listener.

type LogicalReplicationListener 

type LogicalReplicationListener struct {
	// contains filtered or unexported fields
}

LogicalReplicationListener is a Listener that uses logical replication slots to listen for changesets.

func NewLogicalReplicationListener 

func NewLogicalReplicationListener(opts ...LROption) *LogicalReplicationListener

NewLogicalReplicationListener returns a new LogicalReplicationListener.

func (*LogicalReplicationListener) Close 

func (l *LogicalReplicationListener) Close() error

Close closes the database connection.

func (*LogicalReplicationListener) Dial 

func (l *LogicalReplicationListener) Dial(connConfig *pgx.ConnConfig) error

Dial connects to the source database.

func (*LogicalReplicationListener) ListenForChanges 

func (l *LogicalReplicationListener) ListenForChanges(ctx context.Context) (chan *Changeset, chan error)

ListenForChanges returns a channel that emits database changesets.

type NotifyListener 

type NotifyListener struct {
	// contains filtered or unexported fields
}

NotifyListener is a listener that uses Postgres' LISTEN/NOTIFY pattern for subscribing for subscribing to changeset enqueued in a changesets table. For more details see `pkg/schema/changesets`.

func NewNotifyListener 

func NewNotifyListener(opts ...NotifyOption) *NotifyListener

NewNotifyListener returne a new NotifyListener.

func (*NotifyListener) Close 

func (l *NotifyListener) Close() error

Close closes the database connection.

func (*NotifyListener) Dial 

func (l *NotifyListener) Dial(connConfig *pgx.ConnConfig) error

Dial connects to the source database.

func (*NotifyListener) ListenForChanges 

func (l *NotifyListener) ListenForChanges(ctx context.Context) (chan *Changeset, chan error)

ListenForChanges returns a channel that emits database changesets.

type NotifyOption 

type NotifyOption func(*NotifyListener)

NotifyOption is a NotifyListener option function

func StartFromID 

func StartFromID(changesetID int64) NotifyOption

StartFromID is an option for setting the startFromID

func StartFromTimestamp 

func StartFromTimestamp(t time.Time) NotifyOption

StartFromTimestamp is an option for setting the startFromTimestamp

type Option 

type Option func(*WarpPipe)

Option is a WarpPipe option function

func IgnoreTables 

func IgnoreTables(tables []string) Option

IgnoreTables is an option for setting the tables that WarpPipe should ignore. It accepts entries in either of the following formats: 

<schema>.<table>
<schema>.*
<table>

Any tables in this list will negate any whitelisted tables set via WhitelistTables().

func LogLevel 

func LogLevel(level string) Option

LogLevel is an option for setting the logging level.

func WhitelistTables 

func WhitelistTables(tables []string) Option

WhitelistTables is an option for setting a list of tables we want to listen for change from. It accepts entries in either of the following formats: 

<schema>.<table>
<schema>.*
<table>

Any tables set via IgnoreTables() will be excluded.

type Pipeline 

type Pipeline struct {
	// contains filtered or unexported fields
}

Pipeline represents a sequence of stages for processing Changesets.

func NewPipeline 

func NewPipeline() *Pipeline

NewPipeline returns a new Pipeline.

func (*Pipeline) AddStage 

func (p *Pipeline) AddStage(name string, fn StageFunc)

AddStage adds a new Stage to the pipeline

func (*Pipeline) Start 

func (p *Pipeline) Start(ctx context.Context, sourceCh <-chan *Changeset) (<-chan *Changeset, <-chan error)

Start starts the pipeline, consuming off of a source chan that emits *Changeset.

type Stage 

type Stage struct {
	Name string
	Fn   stageFn
}

Stage is a pipeline stage.

type StageFunc 

type StageFunc func(*Changeset) (*Changeset, error)

StageFunc is a function for processing changesets in a pipeline Stage. It accepts a single argument, a Changset, and returns one of: 

(Changeset, nil): If the stage was successful
(nil, nil): If the changeset should be dropped (useful for filtering)
(nil, error): If there was an error during the stage

type WarpPipe 

type WarpPipe struct {
	// contains filtered or unexported fields
}

WarpPipe is a daemon that listens for database changes and transmits them somewhere else.

func NewWarpPipe 

func NewWarpPipe(listener Listener, opts ...Option) *WarpPipe

NewWarpPipe initializes and returns a new WarpPipe.

func (*WarpPipe) Close 

func (w *WarpPipe) Close() error

Close will close the listener and try to gracefully shutdown the WarpPipe.

func (*WarpPipe) ListenForChanges 

func (w *WarpPipe) ListenForChanges(ctx context.Context) (<-chan *Changeset, <-chan error)

ListenForChanges starts the listener listening for database changesets. It returns two channels, on for Changesets, another for errors.

func (*WarpPipe) Open 

func (w *WarpPipe) Open(connConfig *DBConfig) error

Open dials the listener's connection to the database.

Source Files

View all Source files

Directories

Path Synopsis
build
demo-service
cmd
axon
warp-pipe
internal
cli
store

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