[receivers/promtail] add README.md

receiver/promtailreceiver/README.md

@@ -0,0 +1,76 @@
+# Promtail Receiver
+
+| Status                   |           |
+| ------------------------ |-----------|
+| Stability                | [alpha]   |
+| Supported pipeline types | logs      |
+| Distributions            | [contrib] |
+
+This receiver runs [promtail client](https://grafana.com/docs/loki/latest/clients/promtail/) to scrape logs
+
+## Unsupported features
+The Promtail receiver is meant to minimally be a drop-in replacement for Promtail Client. However,
+there are advanced features of Promtail that we don't support and thus explicitly will return
+an error for if the receiver's configuration YAML/code contains any of the following
+
+- [x] [server](https://grafana.com/docs/loki/latest/clients/promtail/configuration/#server)
+- [x] [clients](https://grafana.com/docs/loki/latest/clients/promtail/configuration/#clients)
+- [x] [limits_config](https://grafana.com/docs/loki/latest/clients/promtail/configuration/#limits_config)
+- [x] [options_config](https://grafana.com/docs/loki/latest/clients/promtail/configuration/#options_config)
+
+
+## Getting Started
+
+This receiver is a drop-in replacement for getting Promtail to scrape your
+services. It supports [the full set of Promtail configuration in `scrape_configs`][sc].
+Just like you would write in a YAML configuration
+file before starting Promtail, such as with:
+
+**Note**: Since the collector configuration supports env variable substitution
+`$` characters in your prometheus configuration are interpreted as environment
+variables.  If you want to use $ characters in your promtail configuration,
+you must escape them using `$$`.
+
+```shell
+promtail --config.file=prom.yaml
+```
+
+You can copy and paste that same configuration under:
+
+```yaml
+receivers:
+  promtail:
+    config:
+```
+
+For example:
+
+```yaml
+receivers:
+    promtail:
+      config:
+        positions:
+          filename: /tmp/positions.yaml
+        scrape_configs:
+          - job_name: varlogs
+            static_configs:
+              - labels:
+                job: varlogs
+                __path__: /var/log/*.log
+          - job_name: loki_push
+            server:
+              http_listen_port: 3101
+              grpc_listen_port: 3600
+            labels:
+              pushserver: push1
+              use_incoming_timestamp: true
+        target_config:
+          sync_period: 5s
+```
+
+
+[sc]: https://grafana.com/docs/loki/latest/clients/promtail/configuration/#scrape_configs
+
+[beta]: https://github.com/open-telemetry/opentelemetry-collector#beta
+[contrib]: https://github.com/open-telemetry/opentelemetry-collector-releases/tree/main/distributions/otelcol-contrib
+[core]: https://github.com/open-telemetry/opentelemetry-collector-releases/tree/main/distributions/otelcol

receiver/promtailreceiver/factory.go

@@ -9,7 +9,7 @@ import (
 
 const (
 	typeStr   = "promtail"
-	stability = component.StabilityLevelInDevelopment
+	stability = component.StabilityLevelAlpha
 )
 
 // NewFactory creates a factory for promtail receiver