README.md

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Compose Transporter helps with database transformations from one store to another.  It can also sync from one to another or several stores.

Transporter
===========

About
-----

Transporter allows the user to configure a number of data adaptors as sources or sinks. These can be databases, files or other resources. Data is read from the sources, converted into a message format, and then send down to the sink where the message is converted into a writable format for its destination. The user can also create data transformations in JavaScript which can sit between the source and sink and manipulate or filter the message flow.

Adaptors may be able to track changes as they happen in source data. This "tail" capability allows a Transporter to stay running and keep the sinks in sync.

***BETA Feature***

As of release `v0.4.0`, transporter contains support for being able to resume operations
after being stopped. The feature is disabled by default and can be enabled with the following:

```
source = mongodb({"uri": "mongo://localhost:27017/source_db"})
sink = mongodb({"uri": "mongo://localhost:27017/sink_db"})
t.Config({"log_dir":"/data/transporter"})
  .Source("source", source)
  .Save("sink", sink)
```

When using the above pipeline, all messages will be appended to a commit log and 
successful processing of a message is handled via consumer/sink offset tracking.

Below is a list of each adaptor and its support of the feature:

```
+---------------+-------------+----------------+
|    adaptor    | read resume | write tracking |
+---------------+-------------+----------------+
| elasticsearch |     N/A     |       X        | 
|     file      |             |       X        | 
|    mongodb    |      X      |       X        | 
|  postgresql   |             |       X        | 
|   rabbitmq    |      X      |                | 
|   rethinkdb   |             |       X        | 
+---------------+-------------+----------------+
```

Downloading Transporter
-----------------------

The latest binary releases are available from the [Github Repository](https://github.com/compose/transporter/releases/latest)

Adaptors
--------

Each adaptor has its own README page with details on configuration and capabilities.

* [elasticsearch](./adaptor/elasticsearch)
* [file](./adaptor/file)
* [mongodb](./adaptor/mongodb)
* [postgresql](./adaptor/postgres)
* [rabbitmq](./adaptor/rabbitmq)
* [rethinkdb](./adaptor/rethinkdb)

Native Functions
----------------

Each native function can be used as part of a `Transform` step in the pipeline.

* [goja](./function/gojajs)
* [omit](./function/omit)
* [otto](./function/ottojs)
* [pick](./function/pick)
* [pretty](./function/pretty)
* [rename](./function/rename)
* [skip](./function/skip)

Commands
--------

### init

```
transporter init [source adaptor name] [sink adaptor name]
```

Generates a basic `pipeline.js` file in the current directory.

_Example_
```
$ transporter init mongodb elasticsearch
$ cat pipeline.js
var source = mongodb({
  "uri": "${MONGODB_URI}"
  // "timeout": "30s",
  // "tail": false,
  // "ssl": false,
  // "cacerts": ["/path/to/cert.pem"],
  // "wc": 1,
  // "fsync": false,
  // "bulk": false,
  // "collection_filters": "{}"
})

var sink = elasticsearch({
  "uri": "${ELASTICSEARCH_URI}"
  // "timeout": "10s", // defaults to 30s
  // "aws_access_key": "ABCDEF", // used for signing requests to AWS Elasticsearch service
  // "aws_access_secret": "ABCDEF" // used for signing requests to AWS Elasticsearch service
})

t.Source(source).Save(sink)
// t.Source("source", source).Save("sink", sink)
// t.Source("source", source, "namespace").Save("sink", sink, "namespace")
$
```

Edit the `pipeline.js` file to configure the source and sink nodes and also to set the namespace.

### about

`transporter about`

Lists all the adaptors currently available.

_Example_
```
elasticsearch - an elasticsearch sink adaptor
file - an adaptor that reads / writes files
mongodb - a mongodb adaptor that functions as both a source and a sink
postgres - a postgres adaptor that functions as both a source and a sink
rabbitmq - an adaptor that handles publish/subscribe messaging with RabbitMQ 
rethinkdb - a rethinkdb adaptor that functions as both a source and a sink
```

Giving the name of an adaptor produces more detail, such as the sample configuration.

_Example_
```
transporter about postgres
postgres - a postgres adaptor that functions as both a source and a sink

 Sample configuration:
{
  "uri": "${POSTGRESQL_URI}"
  // "debug": false,
  // "tail": false,
  // "replication_slot": "slot"
}
```

### run

```
transporter run [-log.level "info"] <application.js>
```

Runs the pipeline script file which has its name given as the final parameter.

### test

```
transporter test [-log.level "info"] <application.js>
```

Evaluates and connects the pipeline, sources and sinks. Establishes connections but does not run.
Prints out the state of connections at the end. Useful for debugging new configurations.

### xlog

The `xlog` command is useful for inspecting the current state of the commit log.
It contains 3 subcommands, `current`, `oldest`, and `offset`, as well as 
a required flag `-log_dir` which should be the path to where the commit log is stored.

***NOTE*** the command should only be run against the commit log when transporter
is not actively running.

```
transporter xlog -log_dir=/path/to/dir current
12345
```

Returns the most recent offset appended to the commit log.

```
transporter xlog -log_dir=/path/to/dir oldest
0
```

Returns the oldest offset in the commit log.

```
transporter xlog -log_dir=/path/to/dir show 0
offset    : 0
timestamp : 2017-05-16 11:00:20 -0400 EDT
mode      : COPY
op        : INSERT
key       : MyCollection
value     : {"_id":{"$oid":"58efd14b60d271d7457b4f24"},"i":0}
```

Prints out the entry stored at the provided offset.

### offset

The `offset` command provides access to current state of each consumer (i.e. sink)
offset. It contains 4 subcommands, `list`, `show`, `mark`, and `delete`, as well as 
a required flag `-log_dir` which should be the path to where the commit log is stored.

```
transporter offset -log_dir=/path/to/dir list
+------+---------+
| SINK | OFFSET  |
+------+---------+
| sink | 1103003 |
+------+---------+
```

Lists all consumers and their associated offset in `log_dir`.

```
transporter offset -log_dir=/path/to/dir show sink
+-------------------+---------+
|     NAMESPACE     | OFFSET  |
+-------------------+---------+
| newCollection     | 1102756 |
| testC             | 1103003 |
| MyCollection      |  999429 |
| anotherCollection | 1002997 |
+-------------------+---------+
```

Prints out each namespace and its associated offset.

```
transporter offset -log_dir=/path/to/dir mark sink 1
OK
```

Rewrites the namespace offset map based on the provided offset.

```
transporter offset -log_dir=/path/to/dir delete sink
OK
```

Removes the consumer (i.e. sink) log directory.

#### flags

`-log.level "info"` - sets the logging level. Default is info; can be debug or error.

Building Transporter
--------------------

### Essentials

```
go build ./cmd/transporter/...
```

### Building guides

[macOS](https://github.com/compose/transporter/blob/master/READMEMACOS.md)
[Windows](https://github.com/compose/transporter/blob/master/READMEWINDOWS.md)
[Vagrant](https://github.com/compose/transporter/blob/master/READMEVAGRANT.md)

Transporter Resources
=====================

* [Transporter Wiki](https://github.com/compose/transporter/wiki)
* [Compose's articles](https://www.compose.io/articles/search/?s=transporter)

Contributing to Transporter
===========================

Want to help out with Transporter? Great! There are instructions to get you
started [here](CONTRIBUTING.md).

Licensing
=========
Transporter is licensed under the New BSD License. See LICENSE for full license text.

Support and Guarantees
======================
Compose does not provide support nor guarantee stability or functionality of this tool. Please take adequate caution when using Transporter to ensure that it's the right tool for the job. Transporter may not account for failure scenarios that could lead to unexpected behavior. Always take backups, always test in dev, and always feel free to submit a PR with enhancements, features, and bug fixes.