Allow the Docker image to be run with a random user id

Apply the ownership changes of #12905, without applying the permission
changes, so it still satisfies strict perms checks.

CHANGELOG.next.asciidoc

@@ -266,6 +266,7 @@ https://github.com/elastic/beats/compare/v7.0.0-alpha2...master[Check the HEAD d
 - When using the `decode_json_fields` processor, decoded fields are now deep-merged into existing event. {pull}17958[17958]
 - Add backoff configuration options for the Kafka output. {issue}16777[16777] {pull}17808[17808]
 - Add TLS support to Kerberos authentication in Elasticsearch. {pull}18607[18607]
+- Change ownership of files in docker images so they can be used in secured environments. {pull}12905[12905]
 - Upgrade k8s.io/client-go and k8s keystore tests. {pull}18817[18817]
 
 *Auditbeat*

dev-tools/packaging/templates/docker/Dockerfile.tmpl

@@ -30,7 +30,7 @@ RUN chmod 755 /usr/local/bin/docker-entrypoint
 RUN groupadd --gid 1000 {{ .BeatName }}
 
 RUN mkdir {{ $beatHome }}/data {{ $beatHome }}/logs && \
-    chown -R root:{{ .BeatName }} {{ $beatHome }} && \
+    chown -R root:root {{ $beatHome }} && \
     find {{ $beatHome }} -type d -exec chmod 0750 {} \; && \
     find {{ $beatHome }} -type f -exec chmod 0640 {} \; && \
     chmod 0750 {{ $beatBinary }} && \
@@ -43,7 +43,7 @@ RUN mkdir {{ $beatHome }}/data {{ $beatHome }}/logs && \
     chmod 0770 {{ $beatHome }}/data {{ $beatHome }}/logs
 
 {{- if ne .user "root" }}
-RUN useradd -M --uid 1000 --gid 1000 --home {{ $beatHome }} {{ .user }}
+RUN useradd -M --uid 1000 --gid 1000 --groups 0 --home {{ $beatHome }} {{ .user }}
 {{- end }}
 USER {{ .user }}