feat: make raw format experimental

Author: x1unix

docs/sources/reference/components/loki/loki.source.syslog.md

@@ -18,8 +18,12 @@ For a detailed example, refer to the [Monitor RFC5424-compliant syslog messages
 
 {{< admonition type="note" >}}
 If your messages aren't RFC5424 compliant, you can use `raw` syslog format in combination with the [`loki.process`](./loki.process.md) component.
+
+Please note, that the `raw` syslog format is an [experimental][] feature.
 {{< /admonition >}}
 
+[experimental]: https://grafana.com/docs/release-life-cycle/
+
 The component starts a new syslog listener for each of the given `config` blocks and fans out incoming entries to the list of receivers in `forward_to`.
 
 You can specify multiple `loki.source.syslog` components by giving them different labels.
@@ -146,10 +150,21 @@ The `rfc3164_default_to_current_year`, `use_incoming_timestamp` and `use_rfc5424
   Disables log line parsing. This format allows receiving non-RFC5424 compliant logs, such as [CEF][cef].
   Raw logs can be forwarded to [`loki.process`](./loki.process.md) component for parsing.
 
+{{< admonition type="note" >}}
+The `raw` format is an [experimental][] feature.
+Experimental features are subject to frequent breaking changes, and may be removed with no equivalent replacement.
+To enable and use an experimental feature, you must set the `stability.level` [flag][] to `experimental`.
+{{< /admonition >}}
+
+[flag]: https://grafana.com/docs/alloy/<ALLOY_VERSION>/reference/cli/run/
+[experimental]: https://grafana.com/docs/release-life-cycle/
+
 [cef]: https://www.splunk.com/en_us/blog/learn/common-event-format-cef.html
 
 ### `raw_format_options`
 
+{{< docs/shared lookup="stability/experimental_feature.md" source="alloy" version="<ALLOY_VERSION>" >}}
+
 The `raw_format_options` block configures the `raw` syslog format behavior.
 
 {{< admonition type="note" >}}

internal/component/loki/source/syslog/syslog.go

@@ -2,6 +2,7 @@ package syslog
 
 import (
 	"context"
+	"fmt"
 	"reflect"
 	"sync"
 
@@ -10,6 +11,7 @@ import (
 	"github.com/grafana/alloy/internal/component"
 	"github.com/grafana/alloy/internal/component/common/loki"
 	alloy_relabel "github.com/grafana/alloy/internal/component/common/relabel"
+	scrapeconfig "github.com/grafana/alloy/internal/component/loki/source/syslog/config"
 	st "github.com/grafana/alloy/internal/component/loki/source/syslog/internal/syslogtarget"
 	"github.com/grafana/alloy/internal/featuregate"
 	"github.com/grafana/alloy/internal/runtime/logging/level"
@@ -109,6 +111,10 @@ func (c *Component) Update(args component.Arguments) error {
 	defer c.mut.Unlock()
 
 	newArgs := args.(Arguments)
+	if err := c.checkExperimentalFeatures(newArgs); err != nil {
+		return err
+	}
+
 	prevArgs := c.args
 	c.fanout = newArgs.ForwardTo
 
@@ -125,6 +131,21 @@ func (c *Component) Update(args component.Arguments) error {
 	return nil
 }
 
+func (c *Component) checkExperimentalFeatures(args Arguments) error {
+	isExperimental := c.opts.MinStability.Permits(featuregate.StabilityExperimental)
+	if isExperimental {
+		return nil
+	}
+
+	for _, listener := range args.SyslogListeners {
+		if listener.SyslogFormat == scrapeconfig.SyslogFormatRaw {
+			return fmt.Errorf("%q syslog format is available only at experimental stability level", scrapeconfig.SyslogFormatRaw)
+		}
+	}
+
+	return nil
+}
+
 func (c *Component) startDrainingRoutine() func() {
 	readCtx, cancel := context.WithCancel(context.Background())
 	c.mut.RLock()

internal/component/loki/source/syslog/syslog_test.go

@@ -14,6 +14,9 @@ import (
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 
+	scrapeconfig "github.com/grafana/alloy/internal/component/loki/source/syslog/config"
+	"github.com/grafana/alloy/internal/featuregate"
+
 	"github.com/grafana/alloy/internal/component"
 	"github.com/grafana/alloy/internal/component/common/loki"
 	alloy_relabel "github.com/grafana/alloy/internal/component/common/relabel"
@@ -278,3 +281,25 @@ func TestShutdownAndRebindOnSamePort(t *testing.T) {
 		require.NoError(t, err)
 	}
 }
+
+func TestRawFormatRequiresExperimentalStabilityLevel(t *testing.T) {
+	opts := component.Options{
+		Logger:        util.TestAlloyLogger(t),
+		Registerer:    prometheus.NewRegistry(),
+		OnStateChange: func(e component.Exports) {},
+		MinStability:  featuregate.StabilityGenerallyAvailable,
+	}
+
+	ch1 := loki.NewLogsReceiver()
+	args1 := Arguments{}
+	l1 := DefaultListenerConfig
+	l1.ListenAddress = "127.0.0.1:1234"
+	l1.ListenProtocol = syslogtarget.ProtocolTCP
+	l1.SyslogFormat = scrapeconfig.SyslogFormatRaw
+	args1.SyslogListeners = []ListenerConfig{l1}
+	args1.ForwardTo = []loki.LogsReceiver{ch1}
+
+	_, err := New(opts, args1)
+	require.Error(t, err)
+	require.Error(t, err, "syslog format requires experimental stability level")
+}