feat: add long->wide transformation on back end

README.md

@@ -1,16 +1,59 @@
-# Grafana Data Source Backend Plugin Template
+# InfluxDB IOx Datasource Graafana plugin
 
-[![Build](https://github.com/grafana/grafana-starter-datasource-backend/workflows/CI/badge.svg)](https://github.com/grafana/grafana-datasource-backend/actions?query=workflow%3A%22CI%22)
+**Note**: this is currently an experimental proof-of-concept plugin.
 
-This template is a starting point for building Grafana Data Source Backend Plugins
+## What is it?
+This is a Grafana datasource backend plugin for querying an InfluxDB IOx server via its SQL frontend over Arrow Flight.
+Currently the plugin provides the ability to manage a connection to a database on IOx, via its gRPC API, and also to execute SQL queries against that database.
 
-## What is Grafana Data Source Backend Plugin?
+## How do I use it?
+The plugin is not currently signed so you will need to explicitly give Grafana permission to use it.
+To do that you need to either set the following in your `grafana.ini`
 
-Grafana supports a wide range of data sources, including Prometheus, MySQL, and even Datadog. There’s a good chance you can already visualize metrics from the systems you have set up. In some cases, though, you already have an in-house metrics solution that you’d like to add to your Grafana dashboards. Grafana Data Source Plugins enables integrating such solutions with Grafana.
+```ini
+[plugins]
+;enable_alpha = false
+;app_tls_skip_verify_insecure = false
+# Enter a comma-separated list of plugin identifiers to identify plugins that are allowed to be loaded even if they lack a valid signature.
+allow_loading_unsigned_plugins = influxdata-influxdb-iox-grafana
+;marketplace_url = https://grafana.com/grafana/plugins/
+```
 
-For more information about backend plugins, refer to the documentation on [Backend plugins](https://grafana.com/docs/grafana/latest/developers/plugins/backend/).
+or you will need to set the relevant environment variable:
 
-## Getting started
+```
+GF_PLUGINS_ALLOW_LOADING_UNSIGNED_PLUGINS=influxdata-influxdb-iox-grafana
+```
+
+Oh, you will need the plugin of course! Grab the archive from the releases page on the repo.
+Unpack it an put it somewhere. 
+You will then need to tell Grafana where to look for the plugin, which you can do either by modifying the Grafana config in `grafana.ini`:
+
+```
+#################################### Paths ####################################
+[paths]
+# Path to where grafana can store temp files, sessions, and the sqlite3 db (if that is used)
+;data = /var/lib/grafana
+
+# Temporary files in `data` directory older than given duration will be removed
+;temp_data_lifetime = 24h
+
+# Directory where grafana can store logs
+;logs = /var/log/grafana
+
+# Directory where grafana will automatically scan and look for plugins
+plugins = /Users/me/grafana-dev/plugins/
+```
+
+or by using an env var:
+
+```
+GF_PATHS_PLUGINS=/Users/me/grafana-dev/plugins/
+```
+
+If that all works out then when you restart Grafana it should find it and you should be able to see it as an unsigned datasource.
+
+## Contributing
 
 A data source backend plugin consists of both frontend and backend components.
 

pkg/plugin/flight.go

@@ -5,6 +5,7 @@ import (
 	"encoding/json"
 	"fmt"
 
+	"github.com/apache/arrow/go/arrow"
 	"github.com/apache/arrow/go/arrow/flight"
 	"github.com/grafana/grafana-plugin-sdk-go/backend/log"
 	"github.com/grafana/grafana-plugin-sdk-go/data"
@@ -59,11 +60,36 @@ func (c *FlightClient) query(ctx context.Context, database string, query string)
 		defer rb.Release()
 		log.DefaultLogger.Debug("Record Batch contents", "columns", fmt.Sprintf("%v", rb.Columns()))
 
+		// TODO(edd):
+		//
+		// Figure out how to determine whether to emit long or wide data format.
+		//
+		// I expected to be able to handle this on the front-end via
+		// transformations but it doesn't seem to be working for me.
+		hasTimeColumn := false
+		hasLabelColumn := false
+		for _, field := range rb.Schema().Fields() {
+			if field.Name == "time" && field.Type.ID() != arrow.STRING {
+				hasTimeColumn = true
+			} else if field.Type.ID() == arrow.STRING {
+				hasLabelColumn = true
+			}
+		}
+
 		frame, err := data.FromArrowRecord(rb)
 		if err != nil {
 			log.DefaultLogger.Error("Unable to convert RB to Frame", "error", err)
 			return nil, err
 		}
+
+		if hasLabelColumn && hasTimeColumn {
+			log.DefaultLogger.Debug("Assuming time series WIDE format", "columns", fmt.Sprintf("%v", rb.Columns()))
+			if frame, err = data.LongToWide(frame, nil); err != nil {
+				log.DefaultLogger.Error("Unable to convert frame from long to wide", "error", err)
+				return nil, err
+			}
+		}
+
 		frames = append(frames, frame)
 	}
 

src/datasource.ts

@@ -14,6 +14,7 @@ export class DataSource extends DataSourceWithBackend<MyQuery, MyDataSourceOptio
     };
   }
 
+  // this is basically taken verbatim from the Grafana CSV plugin example.
   async metricFindQuery(query: MyQuery, options?: any) {
     const request = {
       targets: [
@@ -26,15 +27,15 @@ export class DataSource extends DataSourceWithBackend<MyQuery, MyDataSourceOptio
       rangeRaw: options.rangeRaw,
     } as DataQueryRequest<MyQuery>;
 
-    let res: DataQueryResponse;
+    let res: DataQueryResponse | undefined;
 
     try {
       res = await this.query(request).toPromise();
     } catch (err) {
       return Promise.reject(err);
     }
 
-    console.log(res.data);
+    res = res!;
     if (!res.data.length || !res.data[0].fields.length) {
       return [];
     }