out_chronicle: Add documentation (fluent#1084)

Signed-off-by: Hiroshi Hatake <hatake@calyptia.com>

Author: cosmo0920

.gitbook.yaml

@@ -52,6 +52,7 @@ redirects:
     output/azure_kusto:    ./pipeline/outputs/azure_kusto.md
     output/bigquery:       ./pipeline/outputs/bigquery.md
     output/counter:        ./pipeline/outputs/counter.md
+    output/chronicle:      ./pipeline/outputs/chronicle.md
     output/cloudwatch:     ./pipeline/outputs/cloudwatch.md
     output/datadog:        ./pipeline/outputs/datadog.md
     output/es:             ./pipeline/outputs/elasticsearch.md

SUMMARY.md

@@ -160,6 +160,7 @@
   * [FlowCounter](pipeline/outputs/flowcounter.md)
   * [Forward](pipeline/outputs/forward.md)
   * [GELF](pipeline/outputs/gelf.md)
+  * [Google Chronicle](pipeline/outputs/chronicle.md)
   * [Google Cloud BigQuery](pipeline/outputs/bigquery.md)
   * [HTTP](pipeline/outputs/http.md)
   * [InfluxDB](pipeline/outputs/influxdb.md)

pipeline/outputs/chronicle.md

@@ -0,0 +1,56 @@
+---
+
+# Chronicle
+
+The Chronicle output plugin allows ingesting security logs into [Google Chronicle](https://chronicle.security/) serivice. This connector is designed to send unstructured style of security logs.
+
+## Google Cloud Configuration
+
+Fluent Bit streams data into an existing Google Chronicle tenant using a service account that you specify. Therefore, before using the Chronicle output plugin, you must create a service account, create a Google Chronicle tenant, authorize the service account to write to the tenant, and provide the service account credentials to Fluent Bit.
+
+### Creating a Service Account
+
+To stream security logs into Google Chronicle, the first step is to create a Google Cloud service account for Fluent Bit:
+
+* [Creating a Google Cloud Service Account](https://cloud.google.com/iam/docs/creating-managing-service-accounts)
+
+### Creating a Tenant of Google Chronicle
+
+Fluent Bit does not create a tenant of Google Chronicle for your secutiry logs, so you must create this ahead of time.
+
+### Retrieving Service Account Credentials
+
+Fluent Bit Chronicle output plugin uses a JSON credentials file for authentication credentials. Download the credentials file by following these instructions:
+
+* [Creating and Managing Service Account Keys](https://cloud.google.com/iam/docs/creating-managing-service-account-keys)
+
+## Configurations Parameters
+
+| Key | Description | default |
+| :--- | :--- | :--- |
+| google\_service\_credentials | Absolute path to a Google Cloud credentials JSON file. | Value of the environment variable _$GOOGLE\_SERVICE\_CREDENTIALS_ |
+| service\_account\_email | Account email associated to the service. Only available if **no credentials file** has been provided. | Value of environment variable _$SERVICE\_ACCOUNT\_EMAIL_ |
+| service\_account\_secret | Private key content associated with the service account. Only available if **no credentials file** has been provided. | Value of environment variable _$SERVICE\_ACCOUNT\_SECRET_ |
+| project\_id | The project id containing the tenant of Google Chronicle to stream into. | The value of the `project_id` in the credentials file |
+| customer\_id | The customer id to identify the tenant of Google Chronicle to stream into. The value of the `customer_id` should be specified in the configuration file. |  |
+| log\_type | The log type to handle the request entries. Users must set up the valid log types and here is [the supported log types](https://cloud.google.com/chronicle/docs/ingestion/parser-list/supported-default-parsers). Otherwise, the chronicle service denies to handle the ingested logs. |  |
+| region | The GCP region in which to store security logs. Currently, there are several supported regions: `US`, `EU`, `UK`, `ASIA`. Blank is handled as `US`.   |  |
+| log\_key | By default, the whole log record will be sent to Chronocle. If you specify a key name with this option, then only the value of that key will be sent to Chronicle. | |
+
+See Google's [official documentation](https://cloud.google.com/chronicle/docs/reference/ingestion-api)) for further details.
+
+## Configuration File
+
+If you are using a _Google Cloud Credentials File_, the following configuration is enough to get you started:
+
+```text
+[INPUT]
+    Name  dummy
+    Tag   dummy
+
+[OUTPUT]
+    Name       chronicle
+    Match      *
+    customer_id my_customer_id
+    log_type my_super_awesome_type
+```