Initial Commit

.editorconfig

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+root = true
+
+[*]
+indent_style = space
+indent_size = 2
+end_of_line = lf
+charset = utf-8
+trim_trailing_whitespace = true
+insert_final_newline = true
+
+[*.md]
+trim_trailing_whitespace = false

.eslintrc

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+{
+  "extends": [
+    "eslint-config-airbnb-base"
+  ],
+  "env": {
+    "node": true,
+    "mocha": true
+  },
+  "rules": {
+    "arrow-body-style": 0,
+    "consistent-this": [
+      "error",
+      "thiz"
+    ],
+    "comma-dangle": 0,
+    "global-require": 0,
+    "no-unused-vars": [
+      "error",
+      {
+        "vars": "all",
+        "args": "none"
+      }
+    ],
+    "prefer-template": 0,
+    "prefer-const": [
+      2,
+      {
+        "destructuring": "any",
+        "ignoreReadBeforeAssign": true
+      }
+    ],
+    "space-before-function-paren": 0,
+    "prefer-object-spread": 0,
+    "strict": 0
+  },
+  "plugins": [
+    "json"
+  ]
+}

.gitignore

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+node_modules/
+npm-debug.log
+
+coverage/
+
+.vscode
+.project
+.settings
+
+*.log
+*~
+.idea/
+.nyc_output

.npmignore

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+.*
+coverage
+test
+docker-compose.yml

CHANGELOG.md

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+# 0.1.0 / 2023-08-11
+
+- Change Elasticsearch client to Opensearch client.
+- fork from https://github.com/vanthome/winston-elasticsearch/tree/fb870f958d90dcfc9fd75e2eb52260d16a4dc6f5

LICENSE

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+The MIT License (MIT)
+
+Copyright (c) 2015 - 2018 Thomas Hoppe.
+Copyright (c) 2013 Jacques-Olivier D. Bernier.
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in
+all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+THE SOFTWARE.

README.md

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+# winston-opensearch
+
+transport for the [winston](https://github.com/winstonjs/winston) logging toolkit.
+
+Most of code is from the [winston-elasticsearch](https://github.com/vanthome/winston-elasticsearch) version 0.17.3
+
+## Features
+
+- [logstash](https://www.elastic.co/products/logstash) compatible message structure.
+- Thus consumable with [kibana](https://www.elastic.co/products/kibana).
+- Date pattern based index names.
+- Custom transformer function to transform logged data into a different message structure.
+- Buffering of messages in case of unavailability of ES. The limit is the memory as all unwritten messages are kept in memory.
+
+### Compatibility
+
+I tested **Winston 3.8.2**, **Opensearch 2.7** for AWS usage.
+
+## Installation
+
+```sh
+npm install --save winston winston-opensearch
+```
+
+## Usage
+
+```js
+const winston = require('winston');
+const { OpensearchTransport } = require('winston-opensearch');
+
+const esTransportOpts = {
+  level: 'info',
+};
+const esTransport = new OpensearchTransport(esTransportOpts);
+const logger = winston.createLogger({
+  transports: [esTransport],
+});
+// Compulsory error handling
+logger.on('error', (error) => {
+  console.error('Error in logger caught', error);
+});
+esTransport.on('error', (error) => {
+  console.error('Error in logger caught', error);
+});
+```
+
+The [winston API for logging](https://github.com/winstonjs/winston#streams-objectmode-and-info-objects)
+can be used with one restriction: Only one JS object can only be logged and indexed as such.
+If multiple objects are provided as arguments, the contents are stringified.
+
+## Options
+
+- `level` [`info`] Messages logged with a severity greater or equal to the given one are logged to ES; others are discarded.
+- `index` [none | when `dataStream` is `true`, `logs-app-default`] The index to be used. This option is mutually exclusive with `indexPrefix`.
+- `indexPrefix` [`logs`] The prefix to use to generate the index name according to the pattern `<indexPrefix>-<indexSuffixPattern>`. Can be string or function, returning the string to use.
+- `indexSuffixPattern` [`YYYY.MM.DD`] a Day.js compatible date/ time pattern.
+- `transformer` [see below] A transformer function to transform logged data into a different message structure.
+- `useTransformer` [`true`] If set to `true`, the given `transformer` will be used (or the default). Set to `false` if you want to apply custom transformers during Winston's `createLogger`.
+- `ensureIndexTemplate` [`true`] If set to `true`, the given `indexTemplate` is checked/ uploaded to ES when the module is sending the first log message to make sure the log messages are mapped in a sensible manner.
+- `indexTemplate` [see file `index-template-mapping.json`] the mapping template to be ensured as parsed JSON.
+  `ensureIndexTemplate` is `true` and `indexTemplate` is `undefined`
+- `flushInterval` [`2000`] Time span between bulk writes in ms.
+- `retryLimit` [`400`] Number of retries to connect to ES before giving up.
+- `healthCheckTimeout` [`30s`] Timeout for one health check (health checks will be retried forever).
+- `healthCheckWaitForStatus` [`yellow`] Status to wait for when check upon health. See [its API docs](https://www.elastic.co/guide/en/elasticsearch/reference/current/cluster-health.html) for supported options.
+- `healthCheckWaitForNodes` [`>=1`] Nodes to wait for when check upon health. See [its API docs](https://www.elastic.co/guide/en/elasticsearch/reference/current/cluster-health.html) for supported options.
+- `client` An [opensearch client](https://www.npmjs.com/package/@elastic/elasticsearch) instance. If given, the `clientOpts` are ignored.
+- `clientOpts` An object passed to the ES client. See [its docs](https://www.elastic.co/guide/en/elasticsearch/client/javascript-api/current/client-configuration.html) for supported options.
+- `waitForActiveShards` [`1`] Sets the number of shard copies that must be active before proceeding with the bulk operation.
+- `pipeline` [none] Sets the pipeline id to pre-process incoming documents with. See [the bulk API docs](https://www.elastic.co/guide/en/elasticsearch/client/javascript-api/current/api-reference.html#api-bulk).
+- `buffering` [`true`] Boolean flag to enable or disable messages buffering. The `bufferLimit` option is ignored if set to `false`.
+- `bufferLimit` [`null`] Limit for the number of log messages in the buffer.
+- `source` [none] the source of the log message. This can be useful for microservices to understand from which service a log message origins.
+- `internalLogger` [`console.error`] A logger of last resort to log internal errors.
+
+### Logging of OpenSearch Client
+
+The default client and options will log through `console`.
+
+### Interdependencies of Options
+
+When changing the `indexPrefix` and/or the `transformer`,
+make sure to provide a matching `indexTemplate`.
+
+## Transformer
+
+The transformer function allows mutation of log data as provided
+by winston into a shape more appropriate for indexing in Opensearch.
+
+The default transformer generates a `@timestamp` and rolls any `meta`
+objects into an object called `fields`.
+
+Params:
+
+- `logdata` An object with the data to log. Properties are:
+  - `timestamp` [`new Date().toISOString()`] The timestamp of the log entry
+  - `level` The log level of the entry
+  - `message` The message for the log entry
+  - `meta` The meta data for the log entry
+
+Returns: Object with the following properties
+
+- `@timestamp` The timestamp of the log entry
+- `severity` The log level of the entry
+- `message` The message for the log entry
+- `fields` The meta data for the log entry
+
+The default transformer function's transformation is shown below.
+
+Input A:
+
+```js
+{
+  "message": "Some message",
+  "level": "info",
+  "meta": {
+    "method": "GET",
+    "url": "/sitemap.xml",
+    ...
+  }
+}
+```
+
+Output A:
+
+```js
+{
+  "@timestamp": "2019-09-30T05:09:08.282Z",
+  "message": "Some message",
+  "severity": "info",
+  "fields": {
+    "method": "GET",
+    "url": "/sitemap.xml",
+    ...
+  }
+}
+```
+
+The default transformer can be imported and extended
+
+### Example
+
+```js
+const { OpensearchTransformer } = require('winston-opensearch');
+const esTransportOpts = {
+  transformer: (logData) => {
+    const transformed = OpensearchTransformer(logData);
+    transformed.fields.customField = 'customValue';
+    return transformed;
+  },
+};
+const esTransport = new OpensearchTransformer(esTransportOpts);
+```
+
+Note that in current logstash versions, the only "standard fields" are
+`@timestamp` and `@version`, anything else is just free.
+
+A custom transformer function can be provided in the options initiation.
+
+## Events
+
+- `error`: in case of any error.
+
+## Example
+
+An example assuming default settings.
+
+### Log Action
+
+```js
+logger.info('Some message', {});
+```
+
+Only JSON objects are logged from the `meta` field. Any non-object is ignored.
+
+### Generated Message
+
+The log message generated by this module has the following structure:
+
+```js
+{
+  "@timestamp": "2019-09-30T05:09:08.282Z",
+  "message": "Some log message",
+  "severity": "info",
+  "fields": {
+    "method": "GET",
+    "url": "/sitemap.xml",
+    "headers": {
+      "host": "www.example.com",
+      "user-agent": "Mozilla/5.0 (compatible; Googlebot/2.1; +http://www.google.com/bot.html)",
+      "accept": "*/*",
+      "accept-encoding": "gzip,deflate",
+      "from": "googlebot(at)googlebot.com",
+      "if-modified-since": "Tue, 30 Sep 2019 11:34:56 GMT",
+      "x-forwarded-for": "66.249.78.19"
+    }
+  }
+}
+```
+
+### Target Index
+
+This message would be POSTed to the following endpoint:
+
+    http://localhost:9200/logs-2019.09.30/log/
+
+So the default mapping uses an index pattern `logs-*`.