Add filestream ID on standalone kubernetes manifest (#742) (#767)

This commit add unique IDs for the filestream inputs used by the
Kubernetes integration in the Elastic-Agent standalone
Kubernetes configuration/manifest file.

(cherry picked from commit be3c48e)

Co-authored-by: Tiago Queiroz <tiago.queiroz@elastic.co>

CHANGELOG.next.asciidoc

@@ -107,6 +107,7 @@
 - Allow ':' characters in dynamic variables {issue}624[624] {pull}680[680]
 - Allow the - char to appear as part of variable names in eql expressions. {issue}709[709] {pull}710[710]
 - Allow the / char in variable names in eql and transpiler. {issue}715[715] {pull}718[718]
+- Fix data duplication for standalone agent on Kubernetes using the default manifest {issue-beats}31512[31512] {pull}742[742]
 
 ==== New features
 

deploy/kubernetes/elastic-agent-standalone-kubernetes.yaml

@@ -227,6 +227,7 @@ data:
                   fields:
                     ecs.version: 1.12.0
       - name: container-log
+        id: container-log-${kubernetes.pod.name}-${kubernetes.container.id}
         type: filestream
         use_output: default
         meta:
@@ -252,6 +253,7 @@ data:
             paths:
               - /var/log/containers/*${kubernetes.container.id}.log
       - name: audit-log
+        id: audit-log
         type: filestream
         use_output: default
         meta:

deploy/kubernetes/elastic-agent-standalone/elastic-agent-standalone-daemonset-configmap.yaml

@@ -227,6 +227,7 @@ data:
                   fields:
                     ecs.version: 1.12.0
       - name: container-log
+        id: container-log-${kubernetes.pod.name}-${kubernetes.container.id}
         type: filestream
         use_output: default
         meta:
@@ -252,6 +253,7 @@ data:
             paths:
               - /var/log/containers/*${kubernetes.container.id}.log
       - name: audit-log
+        id: audit-log
         type: filestream
         use_output: default
         meta: