# fluent-plugin-gcloud-pubsub-custom

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This plugin is forked from https://github.com/mdoi/fluent-plugin-gcloud-pubsub

## Overview

[Google Cloud Pub/Sub](https://cloud.google.com/pubsub/) Input/Output(BufferedOutput) plugin for [Fluentd](http://www.fluentd.org/) with [google-cloud](https://googlecloudplatform.github.io/google-cloud-ruby/) gem

- Publish messages to Google Cloud Pub/Sub
- Pull messages from Google Cloud Pub/Sub

## Preparation

- Create a project on Google Developer Console
- Add a topic of Cloud Pub/Sub to the project
- Add a pull style subscription to the topic
- Download your credential (json) or [set scope on GCE instance](https://cloud.google.com/compute/docs/api/how-tos/authorization)

When using output plugin, you need to grant Pub/Sub Publisher and Pub/Sub Viewer role to IAM.

Also, when using input plugin, you need to grant Pub/Sub Subscriber and Pub/Sub Viewer role to IAM.

## Requirements

| fluent-plugin-gcloud-pubsub-custom | fluentd | ruby |
|------------------------|---------|------|
| >= 1.0.0 | >= v0.14.0 | >= 2.1 |
|  < 1.0.0 | >= v0.12.0 | >= 1.9 |

## Installation

Install by gem:

```shell
$ gem install fluent-plugin-gcloud-pubsub-custom
```

**Caution**

This plugin doesn't work in [td-agent](http://docs.fluentd.org/articles/install-by-rpm).

Please use in [Fluentd installed by gem](http://docs.fluentd.org/articles/install-by-gem).

## Configuration

### Publish messages

Use `gcloud_pubsub` output plugin.

```
<match example.publish>
  @type gcloud_pubsub
  project <YOUR PROJECT>
  key <YOUR KEY>
  topic <YOUR TOPIC>
  autocreate_topic false
  max_messages 1000
  max_total_size 9800000
  max_message_size 4000000
  <buffer>
    @type memory
    flush_interval 1s
  </buffer>
  <format>
    @type json
  </format>
</match>
```

- `project` (optional)
  - Set your GCP project.
  - Running fluentd on GCP, you don't have to specify.
  - You can also use environment variable such as `GCLOUD_PROJECT`.
- `key` (optional)
  - Set your credential file path.
  - Running fluentd on GCP, you can use scope instead of specifying this.
  - You can also use environment variable such as `GCLOUD_KEYFILE`.
- `topic` (required)
  - Set topic name to publish.
  - You can use placeholder in this param. See: https://docs.fluentd.org/v1.0/articles/buffer-section
- `dest_project` (optional, default: `nil`)
  - Set your destination GCP project if you publish messages cross project.
- `autocreate_topic` (optional, default: `false`)
  - If set to `true`, specified topic will be created when it doesn't exist.
- `max_messages` (optional, default: `1000`)
  - Publishing messages count per request to Cloud Pub/Sub.
    - See https://cloud.google.com/pubsub/quotas#other_limits
- `max_total_size` (optional, default: `9800000` = `9.8MB`)
  - Publishing messages bytesize per request to Cloud Pub/Sub. This parameter affects only message size. You should specify a little smaller value than quota.
    - See https://cloud.google.com/pubsub/quotas#other_limits
- `max_message_size` (optional, default: `4000000` = `4MB`)
  - Messages exceeding `max_message_size` are not published because Pub/Sub clients cannot receive it.
- `attribute_keys` (optional, default: `[]`)
  - Publishing the set fields as attributes.

### Pull messages

Use `gcloud_pubsub` input plugin.

```
<source>
  @type gcloud_pubsub
  tag example.pull
  project <YOUR PROJECT>
  key <YOUR KEY>
  topic <YOUR TOPIC>
  subscription <YOUR SUBSCRIPTION>
  max_messages 1000
  return_immediately true
  pull_interval 0.5
  pull_threads 2
  parse_error_action exception
  enable_rpc true
  rpc_bind 0.0.0.0
  rpc_port 24680
  <parse>
    @type json
  </parse>
</source>
```

- `tag` (required)
  - Set tag of messages.
  - If `tag_key` is specified, `tag` is used as tag when record don't have specified key.
- `tag_key` (optional)
  - Set key to be used as tag.
- `project` (optional)
  - Set your GCP project
  - Running fluentd on GCP, you don't have to specify.
  - You can also use environment variable such as `GCLOUD_PROJECT`.
- `key` (optional)
  - Set your credential file path.
  - Running fluentd on GCP, you can use scope instead of specifying this.
  - You can also use environment variable such as `GCLOUD_KEYFILE`.
- `topic` (optional)
  - Set topic name that the subscription belongs to.
- `subscription` (required)
  - Set subscription name to pull.
- `max_messages` (optional, default: `100`)
  - See maxMessages on https://cloud.google.com/pubsub/docs/reference/rest/v1/projects.subscriptions/pull
- `return_immediately` (optional, default: `true`)
  - See returnImmediately on https://cloud.google.com/pubsub/docs/reference/rest/v1/projects.subscriptions/pull
  - If `return_immediately` is `true` or pulling message is stopped by HTTP RPC, this plugin wait `pull_interval` each pull.
- `pull_interval` (optional, default: `5.0`)
  - Pulling messages by intervals of specified seconds.
- `pull_threads` (optional, default: `1`)
  - Set number of threads to pull messages.
- `attribute_keys` (optional, default: `[]`)
  - Specify the key of the attribute to be emitted as the field of record.
- `parse_error_action` (optional, default: `exception`)
  - Set error type when parsing messages fails.
    - `exception`: Raise exception. Messages are not acknowledged.
    - `warning`: Only logging as warning.
- `enable_rpc` (optional, default: `false`)
  - If `true` is specified, HTTP RPC to stop or start pulling message is enabled.
- `rpc_bind` (optional, default: `0.0.0.0`)
  - Bind IP address for HTTP RPC.
- `rpc_port` (optional, default: `24680`)
  - Port for HTTP RPC.

## Contributing

1. Fork it
2. Create your feature branch (`git checkout -b my-new-feature`)
3. Commit your changes (`git commit -am 'Add some feature'`)
4. Push to the branch (`git push origin my-new-feature`)
5. Create a new Pull Request

## TODO

- Add `tag` attribute in output plugin and use `tag` attribute as tag in input plugin.
- Send ack after other output plugin committed (if possible).

## Authors

- [@mdoi](https://github.com/mdoi) : First author
- [@mia-0032](https://github.com/mia-0032) : This version author