examples: add elasticsearch and prometheus examples

Add examples on how to use lua scripting to push request fields from the RGW to Elasticsearch and Prometheus.

Signed-off-by: Zulai Wang <zl31wang@gmail.com>

examples/lua/config/prometheus.yml

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+global:
+  scrape_interval: 2s # By default, scrape targets every 15 seconds.
+
+  # Attach these labels to any time series or alerts when communicating with
+  # external systems (federation, remote storage, Alertmanager).
+  external_labels:
+    monitor: 'codelab-monitor'
+
+# A scrape configuration containing exactly one endpoint to scrape:
+# Here it's Prometheus itself.
+scrape_configs:
+  # The job name is added as a label `job=<job_name>` to any timeseries scraped from this config.
+  - job_name: 'rgw'
+
+    # Override the global default and scrape targets from this job every 5 seconds.
+    scrape_interval: 1s
+
+    static_configs:
+      - targets: ['127.0.0.1:9091']

examples/lua/elasticsearch_adapter.lua

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+local elasticsearch = require ("elasticsearch")
+local json = require ("lunajson")
+
+local client = elasticsearch.client{
+  hosts = {
+    {
+      host = "localhost",
+      port = "9200"
+    }
+  }
+}
+
+local copyfrom = {}
+if (Request.CopyFrom ~= nil) then
+  copyfrom = {
+    Tenant = Request.CopyFrom.Tenant,
+    Bucket = Request.CopyFrom.Bucket,
+    Object = {
+      Name = Request.CopyFrom.Object.Name,
+      Instance = Request.CopyFrom.Object.Instance,
+      Id = Request.CopyFrom.Object.Id,
+      Size = Request.CopyFrom.Object.Size,
+      MTime = Request.CopyFrom.Object.MTime
+    }
+  }
+end
+
+local res, status = client:index{
+  index = "rgw",
+  type = "Request",
+  id = Request.Id,
+  body = 
+  {
+    RGWOp = Request.RGWOp,
+    DecodedURI = Request.DecodedURI,
+    ContentLength = Request.ContentLength,
+    GenericAttributes = json.encode(Request.GenericAttributes),
+    Response = {
+      HTTPStatusCode = Request.Response.HTTPStatusCode,
+      HTTPStatus = Request.Response.HTTPStatus,
+      RGWCode = Request.Response.RGWCode,
+      Message = Request.Response.Message
+    },
+    SwiftAccountName = Request.SwiftAccountName,
+    Bucket = {
+      Tenant = Request.Bucket.Tenant,
+      Name = Request.Bucket.Name,
+      Marker = Request.Bucket.Marker,
+      Id = Request.Bucket.Id,
+      Count = Request.Bucket.Count,
+      Size = Request.Bucket.Size,
+      ZoneGroupId = Request.Bucket.ZoneGroupId,
+      CreationTime = Request.Bucket.CreationTime,
+      MTime = Request.Bucket.MTime,
+      Quota = {
+        MaxSize = Request.Bucket.Quota.MaxSize,
+        MaxObjects = Request.Bucket.Quota.MaxObjects,
+        Enabled = Request.Bucket.Quota.Enabled,
+        Rounded = Request.Bucket.Quota.Rounded
+      },
+      PlacementRule = {
+        Name = Request.Bucket.PlacementRule.Name,
+        StorageClass = Request.Bucket.PlacementRule.StorageClass
+      },
+      User = {
+        Tenant = Request.Bucket.User.Tenant,
+        Id = Request.Bucket.User.Id
+      }
+    },
+    Object = {
+      Name = Request.Object.Name,
+      Instance = Request.Object.Instance,
+      Id = Request.Object.Id,
+      Size = Request.Object.Size,
+      MTime = Request.Object.MTime
+    },
+    CopyFrom = copyfrom,
+    ObjectOwner = {
+      DisplayName = Request.ObjectOwner.DisplayName,
+      User = {
+        Tenant = Request.ObjectOwner.User.Tenant,
+        Id = Request.ObjectOwner.User.Id
+      }
+    },
+    ZoneGroup = {
+      Name = Request.ZoneGroup.Name,
+      Endpoint = Request.ZoneGroup.Endpoint
+    },
+    Environment = json.encode(Request.Environment),
+    Policy = json.encode(Request.Policy),
+    UserPolicies = json.encode(Request.UserPolicies),
+    RGWId = Request.RGWId,
+    HTTP = {
+      Parameters = json.encode(Request.HTTP.Parameters),
+      Resources = json.encode(Request.HTTP.Resources),
+      Metadata = json.encode(Request.HTTP.Metadata),
+      Host = Request.HTTP.Host,
+      Method = Request.HTTP.Method,
+      URI = Request.HTTP.URI,
+      QueryString = Request.HTTP.QueryString,
+      Domain = Request.HTTP.Domain
+    },
+    Time = Request.Time,
+    Dialect = Request.Dialect,
+    Id = Request.Id,
+    TransactionId = Request.TransactionId,
+    Tags = json.encode(Request.Tags),
+    User = {
+      Tenant = Request.User.Tenant,
+      Id = Request.User.Id
+    }
+  } 
+}
+

examples/lua/elasticsearch_adapter.md

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+# Introduction
+
+This directory contains an example `elasticsearch_adapter.lua` on how to
+use [Lua Scripting](https://docs.ceph.com/en/latest/radosgw/lua-scripting/)
+to push fields of the RGW requests
+to [Elasticsearch](https://www.elastic.co/elasticsearch/).
+
+## Elasticsearch
+
+Install and run Elasticsearch using docker:
+```bash
+docker network create elastic
+docker pull elasticsearch:2.4.6
+docker run --net elastic -p 9200:9200 -p 9300:9300 -e "discovery.type=single-node" elasticsearch:2.4.6
+```
+
+[Full documentation for Elasticsearch installation](https://www.elastic.co/guide/en/elasticsearch/reference/current/setup.html)
+
+## Usage
+
+* Upload the script:
+
+```bash
+radosgw-admin script put --infile=elasticsearch_adapter.lua --context=postRequest
+```
+
+* Add the packages used in the script:
+
+```bash
+radosgw-admin script-package add --package='elasticsearch 1.0.0-1' --allow-compilation
+radosgw-admin script-package add --package='lunajson' --allow-compilation
+radosgw-admin script-package add --package='lua-cjson 2.1.0-1' --allow-compilation
+```
+
+* Restart radosgw.
+
+* Send a request:
+```bash
+s3cmd --host=localhost:8000 --host-bucket="localhost:8000/%(bucket)" --access_key=0555b35654ad1656d804 --secret_key=h7GhxuBLTrlhVUyxSPUKUV8r/2EI4ngqJxD7iBdBYLhwluN30JaT3Q== mb s3://mybucket
+s3cmd --host=localhost:8000 --host-bucket="localhost:8000/%(bucket)" --access_key=0555b35654ad1656d804 --secret_key=h7GhxuBLTrlhVUyxSPUKUV8r/2EI4ngqJxD7iBdBYLhwluN30JaT3Q== put -P /etc/hosts s3://mybucket
+curl http://localhost:8000/mybucket/hosts
+```
+
+* Search by bucket id from Elasticsearch:
+```bash
+curl -X GET "localhost:9200/rgw/_search?pretty" -H 'Content-Type: application/json' -d' 
+{ 
+  "query": { 
+    "match": { 
+      "Bucket.Id": "05382336-b2db-409f-82dc-f28ab5fef978.4471.4471" 
+    } 
+  } 
+} 
+'
+```
+
+## Requirements
+* Lua 5.3
+

examples/lua/prometheus_adapter.lua

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+local http = require("socket.http")
+local ltn12 = require("ltn12")
+
+local respbody = {}
+local op = "rgw_other_request_content_length"
+if (Request.RGWOp == "put_obj") then
+  op = "rgw_put_request_content_length"
+elseif (Request.RGWOp == "get_obj") then
+  op = "rgw_get_request_content_length"
+end
+local field = op .. " " .. tostring(Request.ContentLength) .. "\n"
+
+local body, code, headers, status = http.request{
+  url = "http://127.0.0.1:9091/metrics/job/rgw", 
+  method = "POST",
+  headers = {
+    ["Content-Type"] = "application/x-www-form-urlencoded",
+    ["Content-Length"] = string.len(field)
+  },
+  source = ltn12.source.string(field), 
+  sink = ltn12.sink.table(respbody),
+}
+

examples/lua/prometheus_adapter.md

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+# Introduction
+
+This directory contains an example `prometheus_adapter.lua` on how to
+use [Lua Scripting](https://docs.ceph.com/en/latest/radosgw/lua-scripting/)
+to push metrics from the RGW requests to [Prometheus](https://prometheus.io/), 
+specifically to collect information on object sizes.
+
+## Prometheus
+
+As every single run of a lua script is short-lived,
+so [Pushgateway](https://github.com/prometheus/pushgateway)
+should be used as an intermediate service to enable Prometheus to scrape data
+from RGW.
+
+* Install and run Pushgateway using docker:
+
+```bash
+docker pull prom/pushgateway
+docker run -p 9091:9091 -it prom/pushgateway
+```
+
+* Install and run Prometheus using docker:
+
+```bash
+docker pull prom/prometheus
+docker run --network host -v ${CEPH_DIR}/examples/lua/config/prometheus.yml:/etc/prometheus/prometheus.yml prom/prometheus
+```
+
+[Full documentation for Prometheus installation](https://prometheus.io/docs/prometheus/latest/installation/)
+
+## Usage
+
+* Upload the script:
+
+```bash
+radosgw-admin script put --infile=prometheus_adapter.lua --context=postRequest
+```
+
+* Add the packages used in the script:
+
+```bash
+radosgw-admin script-package add --package='luasocket' --allow-compilation
+```
+
+* Restart radosgw.
+
+* Send a request:
+```bash
+s3cmd --host=localhost:8000 --host-bucket="localhost:8000/%(bucket)" --access_key=0555b35654ad1656d804 --secret_key=h7GhxuBLTrlhVUyxSPUKUV8r/2EI4ngqJxD7iBdBYLhwluN30JaT3Q== mb s3://mybucket
+s3cmd --host=localhost:8000 --host-bucket="localhost:8000/%(bucket)" --access_key=0555b35654ad1656d804 --secret_key=h7GhxuBLTrlhVUyxSPUKUV8r/2EI4ngqJxD7iBdBYLhwluN30JaT3Q== put -P /etc/hosts s3://mybucket
+curl http://localhost:8000/mybucket/hosts
+```
+
+* Open `http://localhost:9090` by browser and search for `rgw_request_content_length`
+![](img/prometheus.png)
+
+## Requirements
+* Lua 5.3 or higher
+