initial

.gitignore

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+httpsql.exe
+httpsql.zip
+config.json

LICENSE

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+The MIT License (MIT)
+
+Copyright (c) 2018 Little brother.
+
+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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+Httpsql is a http server to provides a simple way of monitoring SQL databases via a http request by predefined queries.
+
+### How to build app
+1. Download and install [Golang](https://golang.org/dl/)
+2. Download dependencies
+   ```bash
+   go get -v -d ./
+    ```
+3. Build application
+   ```bash 
+   go build -ldflags="-s -w"
+   ```
+
+Also you can download [binary](https://github.com/little-brother/httpsql/releases).
+
+### How to use
+Before continue you must create `config.json` in app folder. Below is an example:
+
+<pre>
+{
+  "port": "9000",
+  "databases": {
+
+    "demo": {
+      "driver": "mysql",
+      "dns": "myuser@tcp(192.168.0.101)/mydb",
+      "metrics": ["now", "count", "minmax", "getbyid"]
+    },
+
+    "demo2": {
+      "driver": "postgres",
+      "dns": "host=192.168.0.101 user=home password=password dbname=mydb2 sslmode=disable",
+      "metrics": ["count", "minmax"]
+    }
+  },
+
+  "metrics": {
+
+    "now": {
+      "query": "select now()",
+      "description": "Params: none. Returns current date and time."
+    },
+
+    "count": {
+      "query": "select count(1) as count from #table",
+      "description": "Params: table. Returns row count of table."
+    },
+
+    "minmax": {
+      "query": "select min(#column) min, max(#column) max from #table",
+      "description": "Params: table, column. Returns max and min value."
+    },
+
+    "getbyid": {
+      "query": "select * from #table where id = $id",
+      "description": "Params: table, id. Returns row with requested id."
+    }
+  }
+}
+</pre>
+
+The following links will be available for this configuration:
+* `/` returns all database aliases: `demo` and `demo2`
+* `/demo` returns all available metrics for database `demo` and their description
+* `/demo/now` returns `mydb` date and time
+* `/demo/count?table=orders` returns row count for `mydb.orders`
+* `/demo/minmax?table=orders&column=price` returns minimal and maximum `price` in `mydb.orders`
+* `/demo/getbyid?table=orders&id=10` returns order detail with id = `10`
+* `/demo2/count?table=customers` returns customer count in `mydb2.customers`
+* `/demo2/minmax?table=...`
+
+In query `#param` defines a url parameter `param` that value will be substituted directly into the query. To avoid sql injections, all characters except `a-Z0-9_.$` will be removed from value and length is limited to 64 characters. `$param` defines a placeholder parameter and can contains any symbols.
+<br>
+
+Request result is `json` or `text`(csv). By default data format defines by http `Accept` header. You can lock format by adding `json` or `text` to requested url e.g. `/demo2/count?table=customers&text`.
+<br>
+
+| One permanent connection is used for each database. If necessary, the connection will be restored. |
+|---|
+
+### Supported databases
+
+|DBMS|Driver|Dns example|
+|-----|--------|----------|
+|MySQL|[mysql](https://github.com/go-sql-driver/mysql)|myuser@tcp(192.168.0.101)/mydb|
+|PosgreSQL|[postgres](https://github.com/lib/pq)|host=192.168.0.101 user=home password=password dbname=mydb sslmode=disable|
+|MSSQL|[mssql](https://github.com/denisenkom/go-mssqldb)|sqlserver://username:password@host/instance?param1=value&param2=value<br>sqlserver://username:password@host:port?param1=value&param2=value|
+|ADODB|[adodb](https://github.com/mattn/go-adodb)|Provider=Microsoft.Jet.OLEDB.4.0;Data Source=my.mdb;|
+|ODBC|[odbc](https://github.com/alexbrainman/odbc)|Driver={Microsoft ODBC for Oracle};Server=ORACLE8i7;Persist Security Info=False;Trusted_Connection=Yes|
+|ClickHouse|[clickhouse](https://github.com/kshvakov/clickhouse)|tcp://127.0.0.1:9000?username=&debug=true|
+|Firebird|[firebirdsql](https://github.com/nakagami/firebirdsql)|user:password@servername/foo/bar.fdb|
+|SQLite3|[sqlite3](https://github.com/mattn/go-sqlite3)|D:/aaa/bbb/mydb.sqlite|
+
+> Notice: most databases require additional configuration for remote connections
+
+You can add other [drivers](https://github.com/golang/go/wiki/SQLDrivers) but some of them requires additional software.

main.go

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+package main
+import (
+	"fmt"
+	"regexp"
+	"strings"
+	"net/http"
+	"encoding/json"
+	"io/ioutil"
+	"database/sql"
+	_ "github.com/go-sql-driver/mysql"
+	_ "github.com/lib/pq"
+	_ "github.com/denisenkom/go-mssqldb"
+	_ "github.com/mattn/go-adodb"
+	_ "github.com/alexbrainman/odbc"
+	_ "github.com/kshvakov/clickhouse"
+	_ "github.com/nakagami/firebirdsql"
+	_ "github.com/mattn/go-sqlite3"
+
+	// _ "github.com/mattn/go-oci8"
+)
+
+var config Config
+var connections map[string]*sql.DB
+var reSafe = regexp.MustCompile("[^a-zA-Z0-9_\\.$]+")
+
+type Config struct {
+	Port string
+	Databases map[string]Database
+	Metrics map[string]Metric
+}
+
+type Database struct {
+	Driver string
+	Dns string
+	Metrics []string
+}
+
+type Metric struct {
+	Query string
+	Description string
+}
+
+func sendJson(w http.ResponseWriter, data interface{}) {
+	jsonData, err := json.Marshal(data)
+	if err != nil {
+		http.Error(w, err.Error(), http.StatusInternalServerError)	
+		return 
+	}
+
+	w.Header().Set("Content-Type", "application/json")
+	w.Write(jsonData)
+	return
+}
+
+func sendText(w http.ResponseWriter, data []map[string]interface {}, columns []string) {
+	if len(data) == 0 {
+		fmt.Fprintf(w, "")
+		return
+	}
+
+	text := ""
+	for i, row := range (data) {
+		values := make([]string, 0);
+		for _, col := range(columns) {
+			if row[col] != nil {
+				values = append(values, fmt.Sprintf("%v", row[col]))
+			} else {
+				values = append(values, "null")
+			}
+		}
+
+		text = text + strings.Join(values, ";")
+		if i != len(data) - 1 {
+			text = text + "\n"
+		}
+	}
+
+	fmt.Fprintf(w, "%v", text)
+	return
+}
+
+func httpHandler(w http.ResponseWriter, r *http.Request) {
+	url := strings.Split(r.URL.Path, "/")
+	if (len(url) < 2) {
+		http.Error(w, "UNKNOWN", http.StatusInternalServerError)
+		return
+	}
+
+	alias := url[1]
+	metric := ""
+	if len(url) > 2 {
+		metric = url[2]
+	}
+
+	if alias == "" {
+		keys := []string{}
+		for k := range config.Databases {
+			keys = append(keys, k)
+		}
+
+		sendJson(w, keys)
+		return
+	}
+
+	prop, ok := config.Databases[alias]; 
+	if !ok {
+		http.Error(w, "NOT_FOUND", http.StatusNotFound)
+		return
+	}
+
+	if metric == "" {
+		mdesc := make(map[string]string)
+		for _, name := range (prop.Metrics) {
+			m, ok := config.Metrics[name];
+			if ok {
+				mdesc[name] = m.Description			
+			}
+		}
+		sendJson(w, mdesc)
+		return
+	}
+
+	hasMetric := false
+	for _, m := range(config.Databases[alias].Metrics) {
+		hasMetric = hasMetric || m == metric
+	}
+
+	if !hasMetric {
+		http.Error(w, "NOT_FOUND", http.StatusNotFound)
+		return
+	}
+
+	mprop, ok := config.Metrics[metric]; 
+	if  !ok {
+		http.Error(w, "NOT_FOUND", http.StatusNotFound)
+		return
+	}
+
+	var err error
+	db, ok := connections[alias]
+	if !ok || db == nil  {
+		db, err = sql.Open(prop.Driver, prop.Dns)
+		if err != nil {
+			http.Error(w, "ECONNREFUSED", http.StatusInternalServerError)
+			fmt.Println(alias +"/" + metric + "\n", err.Error())
+			return		
+		}
+		connections[alias] = db
+	} else {
+		err = db.Ping()
+		if err != nil {
+			http.Error(w, "ECONNREFUSED", http.StatusInternalServerError)
+			fmt.Println(alias +"/" + metric + "\n", err.Error())
+			defer db.Close()
+			return
+		}
+	}
+
+	query := mprop.Query
+	var params []interface{}
+	for param, value := range (r.URL.Query()) {
+		if len(value) > 0 && len(value[0]) < 64 {
+			val := reSafe.ReplaceAllString(value[0], "")
+			query = strings.Replace(query, "#" + param, val, -1)
+		}
+
+		if len(value) > 0 && strings.Contains(query, "$" + param) {
+			params = append(params, value[0]);
+			query = strings.Replace(query, "$" + param, "?", 1)
+		}
+	}
+
+	rows, err := db.Query(query, params...)
+	if err != nil {
+		http.Error(w, "SQL_ERROR", http.StatusInternalServerError)
+		fmt.Println(alias +"/" + metric + "\n", "Query: ", query, "\n", "Params: ", params, "\n", err.Error())
+		return
+	}
+	defer rows.Close()
+
+	columns, err := rows.Columns()
+	if err != nil {
+		http.Error(w, err.Error(), http.StatusInternalServerError)
+		return
+	}
+
+	count := len(columns)
+	tableData := make([]map[string]interface{}, 0)
+	values := make([]interface{}, count)
+	valuePtrs := make([]interface{}, count)
+	for rows.Next() {
+		for i := 0; i < count; i++ {
+			valuePtrs[i] = &values[i]
+		}
+		rows.Scan(valuePtrs...)
+		entry := make(map[string]interface{})
+		for i, col := range columns {
+			var v interface{}
+			val := values[i]
+			b, ok := val.([]byte)
+			if ok {
+				v = string(b)
+			} else {
+				v = val
+			}
+			entry[col] = v
+		}
+		tableData = append(tableData, entry)
+	}
+
+	_, jsonok := r.URL.Query()["json"]
+	_, textok := r.URL.Query()["text"]
+	if textok || !jsonok && strings.HasPrefix(r.Header.Get("Accept"), "text") {
+		sendText(w, tableData, columns)
+		return
+	}
+
+	sendJson(w, tableData)
+	return
+}
+
+func main() {
+	file, err := ioutil.ReadFile("./config.json")
+	if err != nil {
+		fmt.Printf("Couldn't  read config.json\n", err.Error())
+		return
+	}
+
+	err = json.Unmarshal(file, &config)
+	if err != nil {
+		fmt.Println("Couldn't  parse config.json\n", err.Error())
+		return
+	}
+
+	connections = make(map[string]*sql.DB, 0)
+
+	if config.Port == "" {
+		config.Port = "9000"
+	}
+
+	http.HandleFunc("/", httpHandler)
+	fmt.Println("Httpsql running on " + config.Port + " port\n")
+	err = http.ListenAndServe(":" + config.Port, nil)
+	if err != nil {
+		fmt.Println("Couldn't start http server\n", err.Error())
+		return
+	}
+}