Generic SQL input (#8735)

(cherry picked from commit 908ad2f)

README.md

@@ -324,6 +324,7 @@ For documentation on the latest development code see the [documentation index][d
 * [snmp_trap](./plugins/inputs/snmp_trap)
 * [socket_listener](./plugins/inputs/socket_listener)
 * [solr](./plugins/inputs/solr)
+* [sql](./plugins/inputs/sql) (generic SQL query plugin)
 * [sql server](./plugins/inputs/sqlserver) (microsoft)
 * [stackdriver](./plugins/inputs/stackdriver) (Google Cloud Monitoring)
 * [sql](./plugins/outputs/sql) (SQL generic output)

docs/SQL_DRIVERS_INPUT.md

@@ -0,0 +1,43 @@
+# Available SQL drivers for the SQL input plugin
+
+This is a list of available drivers for the SQL input plugin. The data-source-name (DSN) is driver specific and
+might change between versions. Please check the driver documentation for available options and the format.
+
+database             | driver                                                | aliases         | example DSN                                                                            | comment
+---------------------| ------------------------------------------------------| --------------- | -------------------------------------------------------------------------------------- | -------
+CockroachDB          | [cockroach](https://github.com/jackc/pgx)             | postgres<br>pgx | see _postgres_ driver                                                                  | uses PostgresQL driver
+MariaDB              | [maria](https://github.com/go-sql-driver/mysql)       | mysql           | see _mysql_ driver                                                                     | uses MySQL driver
+Microsoft SQL Server | [sqlserver](https://github.com/denisenkom/go-mssqldb) | mssql           | `username:password@host/instance?param1=value&param2=value`                            | uses newer _sqlserver_ driver
+MySQL                | [mysql](https://github.com/go-sql-driver/mysql)       |                 | `[username[:password]@][protocol[(address)]]/dbname[?param1=value1&...&paramN=valueN]` | see [driver docs](https://github.com/go-sql-driver/mysql) for more information
+PostgreSQL           | [postgres](https://github.com/jackc/pgx)              | pgx             | `[user[:password]@][netloc][:port][,...][/dbname][?param1=value1&...]`                 | see [postgres docs](https://www.postgresql.org/docs/current/libpq-connect.html#LIBPQ-CONNSTRING) for more information
+SQLite               | [sqlite](https://gitlab.com/cznic/sqlite)             |                 | `filename`                                                                             | see [driver docu](https://pkg.go.dev/modernc.org/sqlite) for more information
+TiDB                 | [tidb](https://github.com/go-sql-driver/mysql)        | mysql           | see _mysql_ driver                                                                     | uses MySQL driver
+
+## Comments
+
+### Driver aliases
+Some database drivers are supported though another driver (e.g. CockroachDB). For other databases we provide a more
+obvious name (e.g. postgres) compared to the driver name. For all of those drivers you might use an _alias_ name
+during configuration.
+
+### Example data-source-name DSN
+The given examples are just that, so please check the driver documentation for the exact format
+and available options and parameters. Please note that the format of a DSN might also change
+between driver version.
+
+### Type conversions
+Telegraf relies on type conversion of the database driver and/or the golang sql framework. In case you find
+any problem, please open an issue!
+
+## Help
+If nothing seems to work, you might find help in the telegraf forum or in the chat.
+
+### The documentation is wrong
+Please open an issue or even better send a pull-request!
+
+### I found a bug
+Please open an issue or even better send a pull-request!
+
+### My database is not supported
+We currently cannot support CGO drivers in telegraf! Please check if a **pure Go** driver for the [golang sql framework](https://golang.org/pkg/database/sql/) exists.
+If you found such a driver, please let us know by opening an issue or even better by sending a pull-request!

filter/filter.go

@@ -79,13 +79,24 @@ func compileFilterNoGlob(filters []string) Filter {
 }
 
 type IncludeExcludeFilter struct {
-	include Filter
-	exclude Filter
+	include        Filter
+	exclude        Filter
+	includeDefault bool
+	excludeDefault bool
 }
 
 func NewIncludeExcludeFilter(
 	include []string,
 	exclude []string,
+) (Filter, error) {
+	return NewIncludeExcludeFilterDefaults(include, exclude, true, false)
+}
+
+func NewIncludeExcludeFilterDefaults(
+	include []string,
+	exclude []string,
+	includeDefault bool,
+	excludeDefault bool,
 ) (Filter, error) {
 	in, err := Compile(include)
 	if err != nil {
@@ -97,20 +108,25 @@ func NewIncludeExcludeFilter(
 		return nil, err
 	}
 
-	return &IncludeExcludeFilter{in, ex}, nil
+	return &IncludeExcludeFilter{in, ex, includeDefault, excludeDefault}, nil
 }
 
 func (f *IncludeExcludeFilter) Match(s string) bool {
 	if f.include != nil {
 		if !f.include.Match(s) {
 			return false
 		}
+	} else if !f.includeDefault {
+		return false
 	}
 
 	if f.exclude != nil {
 		if f.exclude.Match(s) {
 			return false
 		}
+	} else if f.excludeDefault {
+		return false
 	}
+
 	return true
 }