From 68b1434a3849158a7c6d3010259028836d5ef851 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Juraci=20Paix=C3=A3o=20Kr=C3=B6hling?= <juraci@kroehling.de>
Date: Mon, 19 Mar 2018 17:02:53 +0100
Subject: [PATCH] Closes #74 - Changed Kubernetes Template to use DaemonSet
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Signed-off-by: Juraci Paixão Kröhling <juraci@kroehling.de>
---
 README.md                              | 30 ++++++++++++++++----
 jaeger-production-template.yml         | 39 ++++++++++++++++++++++++++
 production-elasticsearch/configmap.yml |  3 ++
 production/configmap.yml               |  3 ++
 4 files changed, 69 insertions(+), 6 deletions(-)

diff --git a/README.md b/README.md
index bf4bb46..df010e5 100644
--- a/README.md
+++ b/README.md
@@ -52,7 +52,8 @@ If changes are required for the configuration, the `edit` command can be used:
 
 ### Jaeger components
 
-The main production template deploys the Collector and the Query Service (with UI) as separate individually scalable services.
+The main production template deploys the Collector and the Query Service (with UI) as separate individually scalable services,
+as well as the Agent as `DaemonSet`.
 
     kubectl create -f https://raw.githubusercontent.com/jaegertracing/jaeger-kubernetes/master/jaeger-production-template.yml
 
@@ -60,22 +61,39 @@ If the backing storage is not ready by the time the Collector/Agent start, they
 pod. It's advisable to either wait for the backing storage to stabilize, or to ignore such failures for the first few minutes.
 
 Once everything is ready, `kubectl get service jaeger-query` tells you where to find Jaeger URL, or 
-`minikube service jaeger-query --url` when using `minikube`
+`minikube service jaeger-query --url` when using `minikube`.
+
+As the agent is deployed as a `DaemonSet`, the node's IP address can be stored as an environment variable and passed down
+to the application as:
+
+```yaml
+env:
+- name: JAEGER_AGENT_HOST
+  valueFrom:
+    fieldRef:
+      fieldPath: status.hostIP
+```
 
 ### Deploying the agent as sidecar
 The Jaeger Agent is designed to be deployed local to your service, so that it can receive traces via UDP keeping your
-application's load minimal. As such, it's ideal to have the Agent to be deployed as a sidecar to your application's component,
-just add it as a container within any struct that supports `spec.containers`, like a `Pod`, `Deployment` and so on.
+application's load minimal. By default, the template above installs the agent as a `DaemonSet`, but this means that all
+pods running on a given node will send data to the same agent. If that's not suitable for your workload, an alternative
+is to deploy the agent as a sidecar. To accomplish that, just add it as a container within any struct that supports 
+`spec.containers`, like a `Pod`, `Deployment` and so on. More about this be found on the blog post 
+[Deployment strategies for the Jaeger Agent](https://medium.com/jaegertracing/deployment-strategies-for-the-jaeger-agent-1d6f91796d09).
 
-For instance, assuming that your application is named `myapp` and the image is for it is `mynamespace/hello-myimage`, your
+Assuming that your application is named `myapp` and the image is for it is `mynamespace/hello-myimage`, your
 `Deployment` descriptor would be something like:
 
 ```yaml
-- apiVersion: extensions/v1beta1
+- apiVersion: apps/v1
   kind: Deployment
   metadata:
     name: myapp
   spec:
+    selector:
+      matchLabels:
+        app: myapp
     template:
       metadata:
         labels:
diff --git a/jaeger-production-template.yml b/jaeger-production-template.yml
index 390e81f..0a13ae0 100644
--- a/jaeger-production-template.yml
+++ b/jaeger-production-template.yml
@@ -163,3 +163,42 @@ items:
     selector:
       jaeger-infra: query-pod
     type: LoadBalancer
+- apiVersion: extensions/v1beta1
+  kind: DaemonSet
+  metadata:
+    name: jaeger-agent
+    labels:
+      app: jaeger
+      jaeger-infra: agent-daemonset
+  spec:
+    template:
+      metadata:
+        labels:
+          app: jaeger
+          jaeger-infra: agent-instance
+      spec:
+        containers:
+        - name: agent-instance
+          image: jaegertracing/jaeger-agent:1.2
+          command:
+          - "/go/bin/agent-linux"
+          - "--config-file=/conf/agent.yaml"
+          volumeMounts:
+          - name: jaeger-configuration-volume
+            mountPath: /conf
+          ports:
+          - containerPort: 5775
+            protocol: UDP
+          - containerPort: 6831
+            protocol: UDP
+          - containerPort: 6832
+            protocol: UDP
+        hostNetwork: true
+        dnsPolicy: ClusterFirstWithHostNet
+        volumes:
+          - configMap:
+              name: jaeger-configuration
+              items:
+                - key: agent
+                  path: agent.yaml
+            name: jaeger-configuration-volume
diff --git a/production-elasticsearch/configmap.yml b/production-elasticsearch/configmap.yml
index a6b2605..0780730 100644
--- a/production-elasticsearch/configmap.yml
+++ b/production-elasticsearch/configmap.yml
@@ -36,3 +36,6 @@ data:
       password: changeme
     query:
       static-files: /go/jaeger-ui/
+  agent: |
+    collector:
+      host-port: "jaeger-collector:14267"
diff --git a/production/configmap.yml b/production/configmap.yml
index 3575077..65a72ad 100644
--- a/production/configmap.yml
+++ b/production/configmap.yml
@@ -34,3 +34,6 @@ data:
       keyspace: jaeger_v1_dc1
     query:
       static-files: /go/jaeger-ui/
+  agent: |
+    collector:
+      host-port: "jaeger-collector:14267"