Document how to get promtail running locally.

Signed-off-by: Tom Wilkie <tom.wilkie@gmail.com>

.gitignore

@@ -6,3 +6,4 @@ mixin/vendor/
 cmd/tempo/tempo
 cmd/promtail/promtail
 /tempo
+/promtail

README.md

@@ -8,11 +8,25 @@ not index the contents of the logs, but rather a set of labels for each log stea
 
 ## Run it locally
 
-Tempo can be run in a single host, no-dependencies mode using the following commands:
+Tempo can be run in a single host, no-dependencies mode using the following commands.
+
+Tempo consists of 3 components; `tempo` is the main server, responsible for storing
+logs and processing queries.  `promtail` is the agent, responsible for gather logs
+and sending them to tempo and `grafana` as the UI.
+
+To run tempo, use the following commands:
 
 ```
 $ go build ./cmd/tempo
-$ ./tempo -config.file=./docs/local.yaml
+$ ./tempo -config.file=./docs/tempo-local-config.yaml
+...
+```
+
+To run promtail, use the following commands:
+
+```
+$ go build ./cmd/promtail
+$ ./promtail -config.file=./docs/promtail-local-config.yaml -positions.file=./positions.yaml -client.url=http://localhost/api/prom/push
 ...
 ```
 
@@ -89,73 +103,3 @@ Args:
   <query>    eg '{foo="bar",baz="blip"}'
   [<regex>]
 ```
-
-## API
-
-*nb* Authentication is out of scope for this project.  You are expected to run an
-authenticating reverse proxy in front of our services, such as an Nginx with basic
-auth or a OAuth2 proxy.
-
-There are 4 API endpoints:
-
-- `POST /api/prom/push`
-
-  For sending log entries, expects a snappy compresses proto in the HTTP Body.
-
-- `GET /api/prom/query`
-
-  For doing queries, accepts the following paramters in the query-string:
-  - `query`: a logQL query
-  - `limit`: max number of entries to return
-  - `start`: the start time for the query, as a nanosecond Unix epoch (nanoseconds since 1970)
-  - `end`: the end time for the query, as a nanosecond Unix epoch (nanoseconds since 1970)
-  - `direction`: `forward` or `backward`, useful when specifying a limit
-  - `regexp`: a regex to filter the returned results, will eventually be rolled into the query language
-
-  Responses looks like this:
-  ```
-  {
-    "streams": [
-      {
-        "labels": "{instance=\"...\", job=\"...\", namespace=\"...\"}",
-        "entries": [
-          {
-            "timestamp": "2018-06-27T05:20:28.699492635Z",
-            "line": "..."
-          },
-          ...
-        ]
-      },
-      ...
-    ]
-  }
-  ```
-
-- `GET /api/prom/label`
-
-  For retrieving the names of the labels one can query on.
-
-  Responses looks like this:
-  ```
-  {
-    "values": [
-      "instance",
-      "job",
-      ...
-    ]
-  }
-  ```
-
-- `GET /api/prom/label/<name>/values`
-  For retrieving the label values one can query on.
-
-  Responses looks like this:
-  ```
-  {
-    "values": [
-      "default",
-      "cortex-ops",
-      ...
-    ]
-  }
-  ```

cmd/tempo/main.go

@@ -62,7 +62,7 @@ func readConfig(filename string, cfg *tempo.Config) error {
 		return errors.Wrap(err, "Error reading config file: %v")
 	}
 
-	if err := yaml.Unmarshal(buf, &cfg); err != nil {
+	if err := yaml.UnmarshalStrict(buf, &cfg); err != nil {
 		return errors.Wrap(err, "Error reading config file: %v")
 	}
 	return nil

docs/api.md

@@ -0,0 +1,70 @@
+
+## API
+
+*nb* Authentication is out of scope for this project.  You are expected to run an
+authenticating reverse proxy in front of our services, such as an Nginx with basic
+auth or a OAuth2 proxy.
+
+There are 4 API endpoints:
+
+- `POST /api/prom/push`
+
+  For sending log entries, expects a snappy compresses proto in the HTTP Body.
+
+- `GET /api/prom/query`
+
+  For doing queries, accepts the following paramters in the query-string:
+  - `query`: a logQL query
+  - `limit`: max number of entries to return
+  - `start`: the start time for the query, as a nanosecond Unix epoch (nanoseconds since 1970)
+  - `end`: the end time for the query, as a nanosecond Unix epoch (nanoseconds since 1970)
+  - `direction`: `forward` or `backward`, useful when specifying a limit
+  - `regexp`: a regex to filter the returned results, will eventually be rolled into the query language
+
+  Responses looks like this:
+  ```
+  {
+    "streams": [
+      {
+        "labels": "{instance=\"...\", job=\"...\", namespace=\"...\"}",
+        "entries": [
+          {
+            "timestamp": "2018-06-27T05:20:28.699492635Z",
+            "line": "..."
+          },
+          ...
+        ]
+      },
+      ...
+    ]
+  }
+  ```
+
+- `GET /api/prom/label`
+
+  For retrieving the names of the labels one can query on.
+
+  Responses looks like this:
+  ```
+  {
+    "values": [
+      "instance",
+      "job",
+      ...
+    ]
+  }
+  ```
+
+- `GET /api/prom/label/<name>/values`
+  For retrieving the label values one can query on.
+
+  Responses looks like this:
+  ```
+  {
+    "values": [
+      "default",
+      "cortex-ops",
+      ...
+    ]
+  }
+  ```

docs/promtail-local-config.yaml

@@ -0,0 +1,9 @@
+scrape_configs:
+- job_name: system
+
+  static_configs:
+  - targets:
+      - localhost
+    labels:
+      job: system
+      __path__: /var/log/system.log

pkg/promtail/config.go

@@ -4,20 +4,17 @@ import (
 	"fmt"
 	"io/ioutil"
 	"path/filepath"
-	"strings"
 
 	yaml "gopkg.in/yaml.v2"
 
 	"github.com/prometheus/prometheus/config"
 	sd_config "github.com/prometheus/prometheus/discovery/config"
+	"github.com/prometheus/prometheus/discovery/targetgroup"
 )
 
 // Config for promtail, describing what files to watch.
 type Config struct {
 	ScrapeConfig []ScrapeConfig `yaml:"scrape_configs,omitempty"`
-
-	// Catches all undefined fields and must be empty after parsing.
-	XXX map[string]interface{} `yaml:",inline"`
 }
 
 // LoadConfig loads config from a file.
@@ -28,34 +25,19 @@ func LoadConfig(filename string) (*Config, error) {
 	}
 
 	var cfg Config
-	if err := yaml.Unmarshal(buf, &cfg); err != nil {
+	if err := yaml.UnmarshalStrict(buf, &cfg); err != nil {
 		return nil, err
 	}
 
 	return &cfg, nil
 }
 
-// UnmarshalYAML implements the yaml.Unmarshaler interface.
-func (c *Config) UnmarshalYAML(unmarshal func(interface{}) error) error {
-	type plain Config
-	err := unmarshal((*plain)(c))
-	if err != nil {
-		return err
-	}
-	if err = checkOverflow(c.XXX, "config"); err != nil {
-		return err
-	}
-	return nil
-}
-
 // ScrapeConfig describes a job to scrape.
 type ScrapeConfig struct {
 	JobName                string                           `yaml:"job_name,omitempty"`
-	ServiceDiscoveryConfig sd_config.ServiceDiscoveryConfig `yaml:",inline"`
 	RelabelConfigs         []*config.RelabelConfig          `yaml:"relabel_configs,omitempty"`
-
-	// Catches all undefined fields and must be empty after parsing.
-	XXX map[string]interface{} `yaml:",inline"`
+	ServiceDiscoveryConfig sd_config.ServiceDiscoveryConfig `yaml:",inline"`
+	StaticConfig           targetgroup.Group                `yaml:"static_config"`
 }
 
 // UnmarshalYAML implements the yaml.Unmarshaler interface.
@@ -65,22 +47,8 @@ func (c *ScrapeConfig) UnmarshalYAML(unmarshal func(interface{}) error) error {
 	if err != nil {
 		return err
 	}
-	if err = checkOverflow(c.XXX, "scrape_config"); err != nil {
-		return err
-	}
 	if len(c.JobName) == 0 {
 		return fmt.Errorf("job_name is empty")
 	}
 	return nil
 }
-
-func checkOverflow(m map[string]interface{}, ctx string) error {
-	if len(m) > 0 {
-		var keys []string
-		for k := range m {
-			keys = append(keys, k)
-		}
-		return fmt.Errorf("unknown fields in %s: %s", ctx, strings.Join(keys, ", "))
-	}
-	return nil
-}

pkg/promtail/position.go

@@ -111,7 +111,7 @@ func readPositionsFile(filename string) (map[string]int64, error) {
 	}
 
 	var p positionsFile
-	if err := yaml.Unmarshal(buf, &p); err != nil {
+	if err := yaml.UnmarshalStrict(buf, &p); err != nil {
 		return nil, err
 	}
 

pkg/promtail/target.go

@@ -8,6 +8,7 @@ import (
 
 	"github.com/grafana/tempo/pkg/helpers"
 	"github.com/hpcloud/tail"
+	"github.com/pkg/errors"
 	"github.com/prometheus/client_golang/prometheus"
 	"github.com/prometheus/common/model"
 	log "github.com/sirupsen/logrus"
@@ -41,16 +42,14 @@ type Target struct {
 
 // NewTarget create a new Target.
 func NewTarget(c *Client, positions *Positions, path string, labels model.LabelSet) (*Target, error) {
-	log.Info("newTarget", labels)
-
 	watcher, err := fsnotify.NewWatcher()
 	if err != nil {
-		return nil, err
+		return nil, errors.Wrap(err, "fsnotify.NewWatcher")
 	}
 
 	if err := watcher.Add(path); err != nil {
 		helpers.LogError("closing watcher", watcher.Close)
-		return nil, err
+		return nil, errors.Wrap(err, "watcher.Add")
 	}
 
 	t := &Target{
@@ -66,7 +65,7 @@ func NewTarget(c *Client, positions *Positions, path string, labels model.LabelS
 	// Fist, we're going to add all the existing files
 	fis, err := ioutil.ReadDir(t.path)
 	if err != nil {
-		return nil, err
+		return nil, errors.Wrap(err, "ioutil.ReadDir")
 	}
 	for _, fi := range fis {
 		if fi.IsDir() {

pkg/promtail/targetmanager.go

@@ -61,7 +61,6 @@ func NewTargetManager(
 	}
 
 	config := map[string]sd_config.ServiceDiscoveryConfig{}
-
 	for _, cfg := range scrapeConfig {
 		s := &syncer{
 			log:           logger,
@@ -75,6 +74,7 @@ func NewTargetManager(
 	}
 
 	go tm.run()
+	go tm.manager.Run()
 
 	return tm, tm.manager.ApplyConfig(config)
 }
@@ -109,10 +109,13 @@ func (s *syncer) Sync(groups []*targetgroup.Group) {
 
 	for _, group := range groups {
 		for _, t := range group.Targets {
+			level.Debug(s.log).Log("msg", "new target", "labels", t)
+
 			labels := group.Labels.Merge(t)
 			labels = relabel.Process(labels, s.relabelConfig...)
 			// Drop empty targets (drop in relabeling).
 			if labels == nil {
+				level.Debug(s.log).Log("msg", "dropping target, no labels")
 				continue
 			}