docs(stage): add docker and cri

docs/clients/promtail/pipelines.md

@@ -188,6 +188,8 @@ given log entry.
 
 Parsing stages:
 
+  * [docker](./stages/docker.md): Extract data by parsing the log line as docker format.
+  * [cri](./stages/cri.md): Extract data by parsing the log line as cri format.
   * [regex](./stages/regex.md): Extract data using a regular expression.
   * [json](./stages/json.md): Extract data by parsing the log line as JSON.
 

docs/clients/promtail/stages/cri.md

@@ -0,0 +1,41 @@
+# `cri` stage
+
+The `cri` stage is a parsing stage that reads the log line as the way that cri generated.
+
+## Format
+
+Each log from cri is string format and covert following three parts:
+1. `log`: the content of log
+2. `stream`: stdout/stderr
+3. `time`: the timestamp string of log
+
+Each part is splited with blank with others and no blanks in each part.
+
+So in the following logs, only the first is cri format which `cri` stage can format:
+```
+"2019-01-01T01:00:00.000000001Z stderr P test\ngood"
+"2019-01-01 T01:00:00.000000001Z stderr testgood"
+"2019-01-01T01:00:00.000000001Z testgood"
+```
+
+More case refer to [entry_parser_test](../../../../pkg/promtail/api/entry_parser_test.go).
+
+## Examples
+
+### Using log line
+
+```yaml
+cri: {}
+```
+
+Given the following log line:
+
+```
+"2019-04-30T02:12:41.8443515Z stdout xx message"
+```
+
+The following key-value pairs would be created in the set of extracted data:
+
+- `output`: `message`
+- `stream`: `stdout`
+- `timestamp`: `2019-04-30T02:12:41.8443515`

docs/clients/promtail/stages/docker.md

@@ -0,0 +1,31 @@
+# `docker` stage
+
+The `docker` stage is a parsing stage that reads the log line as the way that docker generated.
+It works similar with `json` stage but no need to set anything.
+
+## Format
+
+Each log from docker is json format and covert following three keys:
+1. `log`: the content of log
+2. `stream`: stdout/stderr
+3. `time`: the timestamp string of log
+
+## Examples
+
+### Using log line
+
+```yaml
+docker: {}
+```
+
+Given the following log line:
+
+```
+{"log":"log message\n","stream":"stderr","time":"2019-04-30T02:12:41.8443515Z"}
+```
+
+The following key-value pairs would be created in the set of extracted data:
+
+- `output`: `log message\n`
+- `stream`: `stderr`
+- `timestamp`: `2019-04-30T02:12:41.8443515`