using an environment variable passed into an arg instead of reading the pod...

using an environment variable passed into an arg instead of reading the pod name from a file and the downardApi
added a makefile

.gitignore

+loki-canary
\ No newline at end of file

Makefile

+.PHONY: all build test clean build-image push-image
+.DEFAULT_GOAL := all
+
+IMAGE_PREFIX ?= grafana
+IMAGE_TAG := $(shell ./tools/image-tag)
+
+all: test build-image
+
+build:
+	go build -o loki-canary -v cmd/loki-canary/main.go
+
+test:
+	go test -v ./...
+
+clean:
+	rm -f ./loki-canary
+	go clean ./...
+
+build-image:
+	docker build -t $(IMAGE_PREFIX)/loki-canary .
+	docker tag $(IMAGE_PREFIX)/loki-canary $(IMAGE_PREFIX)/loki-canary:$(IMAGE_TAG)
+
+push-image:
+	docker push $(IMAGE_PREFIX)/loki-canary:$(IMAGE_TAG)
+	docker push $(IMAGE_PREFIX)/loki-canary:latest
\ No newline at end of file

cmd/loki-canary/main.go

@@ -3,7 +3,6 @@ package main
 import (
 	"flag"
 	"fmt"
-	"io/ioutil"
 	"net/http"
 	"net/url"
 	"os"
@@ -22,7 +21,6 @@ func main() {
 
 	lName := flag.String("labelname", "name", "The label name for this instance of loki-canary to use in the log selector")
 	lVal := flag.String("labelvalue", "loki-canary", "The unique label value for this instance of loki-canary to use in the log selector")
-	usePodName := flag.Bool("usepod", false, "If true, loki-canary will read the pod name from /etc/loki-canary/pod_name as the unique label value")
 	port := flag.Int("port", 3500, "Port which loki-canary should expose metrics")
 	addr := flag.String("addr", "", "The Loki server URL:Port, e.g. loki:3100")
 	tls := flag.Bool("tls", false, "Does the loki connection use TLS?")
@@ -34,17 +32,9 @@ func main() {
 	wait := flag.Duration("wait", 60*time.Second, "Duration to wait for log entries before reporting them lost")
 	flag.Parse()
 
-	val := *lVal
-	if *usePodName {
-		data, err := ioutil.ReadFile("/etc/loki-canary/name")
-		if err != nil {
-			panic(err)
-		}
-		val = string(data)
-	}
-
 	if *addr == "" {
-		panic("Must specify a Loki address with -addr")
+		_, _ = fmt.Fprintf(os.Stderr, "Must specify a Loki address with -addr\n")
+		os.Exit(1)
 	}
 
 	var ui *url.Userinfo
@@ -62,10 +52,10 @@ func main() {
 		Host:     *addr,
 		User:     ui,
 		Path:     "/api/prom/tail",
-		RawQuery: "query=" + url.QueryEscape(fmt.Sprintf("{stream=\"stdout\",%v=\"%v\"}", *lName, val)),
+		RawQuery: "query=" + url.QueryEscape(fmt.Sprintf("{stream=\"stdout\",%v=\"%v\"}", *lName, *lVal)),
 	}
 
-	_, _ = fmt.Fprintf(os.Stderr, "Connecting to loki at %v, querying for label '%v' with value '%v'\n", u.String(), *lName, val)
+	_, _ = fmt.Fprintf(os.Stderr, "Connecting to loki at %v, querying for label '%v' with value '%v'\n", u.String(), *lName, *lVal)
 
 	c := comparator.NewComparator(os.Stderr, *wait, 1*time.Second)
 	w := writer.NewWriter(os.Stdout, c, *interval, *size)

production/ksonnet/loki-canary/loki-canary.libsonnet

@@ -3,10 +3,12 @@ local k = import 'ksonnet-util/kausal.libsonnet';
 k {
   local container = $.core.v1.container,
 
-  loki_canary_args:: {},
+  loki_canary_args:: {
+    labelvalue: "$(POD_NAME)",
+  },
 
   _images+:: {
-    loki_canary: 'loki-canary:latest',
+    loki_canary: 'grafana/loki-canary:latest',
   },
 
   loki_canary_container::
@@ -15,32 +17,11 @@ k {
     container.withArgsMixin($.util.mapToFlags($.loki_canary_args)) +
     container.withEnv([
       container.envType.fromFieldPath('HOSTNAME', 'spec.nodeName'),
+      container.envType.fromFieldPath('POD_NAME', 'metadata.name'),
     ]),
 
   local daemonSet = $.extensions.v1beta1.daemonSet,
 
-  local downwardApiMount(name, path, volumeMountMixin={}) =
-        local container = $.core.v1.container,
-              deployment = $.extensions.v1beta1.deployment,
-              volumeMount = $.core.v1.volumeMount,
-              volume = $.core.v1.volume,
-              addMount(c) = c + container.withVolumeMountsMixin(
-          volumeMount.new(name, path) +
-          volumeMountMixin,
-        );
-
-        deployment.mapContainers(addMount) +
-        deployment.mixin.spec.template.spec.withVolumesMixin([
-          volume.withName(name) +
-          volume.mixin.downwardApi.withItems([
-            {
-              path: "name",
-              fieldRef: { fieldPath: "metadata.name" },
-            },
-          ]),
-        ]),
-
   loki_canary_daemonset:
-    daemonSet.new('loki-canary', [$.loki_canary_container]) +
-    downwardApiMount('pod-name', '/etc/loki-canary'),
+    daemonSet.new('loki-canary', [$.loki_canary_container]),
 }
\ No newline at end of file

tools/image-tag

+#!/usr/bin/env bash
+
+set -o errexit
+set -o nounset
+set -o pipefail
+
+WORKING_SUFFIX=$(if git status --porcelain | grep -qE '^(?:[^?][^ ]|[^ ][^?])\s'; then echo "-WIP"; else echo ""; fi)
+BRANCH_PREFIX=$(git rev-parse --abbrev-ref HEAD)
+echo "${BRANCH_PREFIX//\//-}-$(git rev-parse --short HEAD)$WORKING_SUFFIX"