[Heartbeat] Unpack beats at build time on docker (#202)

* unpack beats at build time on docker

* Add comment on heartbeat caps

dev-tools/packaging/packages.yml

@@ -482,6 +482,7 @@ shared:
       user: '{{ .BeatName }}'
       linux_capabilities: ''
       image_name: ''
+      beats_install_path: "install"
     files:
       'elastic-agent.yml':
         source: 'elastic-agent.docker.yml'

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

@@ -32,7 +32,7 @@ FROM {{ .from }}
 ENV BEAT_SETUID_AS={{ .user }}
 
 {{- if contains .from "ubi-minimal" }}
-RUN for iter in {1..10}; do microdnf update -y && microdnf install -y findutils shadow-utils && microdnf clean all && exit_code=0 && break || exit_code=$? && echo "microdnf error: retry $iter in 10s" && sleep 10; done; (exit $exit_code)
+RUN for iter in {1..10}; do microdnf update -y && microdnf install -y tar gzip findutils shadow-utils && microdnf clean all && exit_code=0 && break || exit_code=$? && echo "microdnf error: retry $iter in 10s" && sleep 10; done; (exit $exit_code)
 {{- else }}
 
 RUN for iter in {1..10}; do \
@@ -181,6 +181,18 @@ RUN mkdir /app
 RUN chown {{ .user }} /app
 {{- end }}
 {{- end }}
+
+# Unpack beats to default install directory
+RUN mkdir -p {{ $beatHome }}/data/{{.BeatName}}-{{ commit_short }}/{{ .beats_install_path }} && \
+    for beatPath in {{ $beatHome }}/data/{{.BeatName}}-{{ commit_short }}/downloads/*.tar.gz; do \
+    tar xf $beatPath -C {{ $beatHome }}/data/{{.BeatName}}-{{ commit_short }}/{{ .beats_install_path }}; \
+    done && \
+    chown -R {{ .user }}:{{ .user }} {{ $beatHome }}/data/{{.BeatName}}-{{ commit_short }}/{{ .beats_install_path }} && \
+    chown -R root:root {{ $beatHome }}/data/{{.BeatName}}-{{ commit_short }}/{{ .beats_install_path }}/*/*.yml && \
+    chmod 0644 {{ $beatHome }}/data/{{.BeatName}}-{{ commit_short }}/{{ .beats_install_path }}/*/*.yml && \
+    # heartbeat requires cap_net_raw,cap_setuid to run ICMP checks and change npm user
+    setcap cap_net_raw,cap_setuid+p {{ $beatHome }}/data/{{.BeatName}}-{{ commit_short }}/{{ .beats_install_path }}/heartbeat-*/heartbeat
+
 USER {{ .user }}
 
 {{- if (and (contains .image_name "-complete") (not (contains .from "ubi-minimal")))  }}