Add API documentation for log search (#378)

logsearchapi/README.md

@@ -31,3 +31,46 @@ mc admin service restart myminio
 ```shell
 curl -v "http://localhost:8080/api/query?token=yyy&q=raw&pageNo=0&pageSize=10&timeStart=2020-11-04T22:26:12.732402319Z"
 ```
+
+## API Documentation
+
+### Ingest 
+
+```
+POST `/api/ingest?token=xxx`
+```
+
+This API is used to send MinIO audit logs for ingestion into the API service.
+
+The `token` parameter is used to authenticate the request and should be equal to the `LOGSEARCH_AUDIT_AUTH_TOKEN` environment variable passed to the server.
+
+The body must be a JSON object representing a single audit log object created by a MinIO server.
+
+This endpoint must be configured as the audit log endpoint in the MinIO server.
+
+### Query
+
+```
+GET /api/query?token=xxx&...
+```
+
+This API is used to query MinIO audit logs stored by the API service.
+
+The `token` parameter is used to authenticate the request and should be equal to the `LOGSEARCH_QUERY_AUTH_TOKEN` environment variable passed to the server.
+
+Additional query parameters specify the logs to be retrieved.
+
+| Query parameter      | Value Description                                                                                                 | Required | Default             |
+|----------------------|-------------------------------------------------------------------------------------------------------------------|----------|---------------------|
+| `q`                  | `reqinfo` or `raw`.                                                                                               | Yes      | -                   |
+| `timeStart`          | RFC3339 time or date. Examples: `2006-01-02T15:04:05.999999999Z07:00` or `2006-01-02`.                            | No       | Current server time |
+| `timeAsc`/`timeDesc` | Flag parameter (no value); either one may be specified. Specifies result ordering.                                | No       | `timeDesc`          |
+| `pageSize`           | Number of results to return per API call. Allows values between 10 and 1000.                                      | No       | `10`                |
+| `pageNo`             | 0-based page number of results.                                                                                   | No       | `0`                 |
+| `fp`                 | Repeatable parameter specifying key-value match filters. See the [filter parameters](#filter-parameters) section. | No       | -                   |
+
+#### Filter Parameters
+
+Filter parameters only work when `q=reqinfo` is set. Filter parameters allow filtering records based on key-value pattern matching. 
+
+The format for each filter pattern is `key:value-pattern`. The `key` is the name of the field to match on can be one of `bucket`, `object`, `api_name`, `request_id`, `user_agent` or `response_status`. The value is a glob expression using `.` to signify any single character and `*` to match any number of characters. For example `bucket:photos-*` matches any bucket with a `photos-` prefix. To match a literal `.` or `*` prefix it with a `\`. To match a literal `\`, just double it: `\\`.