Fix issue when building Agent snapshot and enable building the agent. (…

…elastic#16927)

An extension in the generated files ("SNAPSHOT") was preventing us to
correctly generate the agent artifact with the packaged
metricbeat/filebeat.

Fixes: elastic#16908
(cherry picked from commit 62d3683)

Makefile

@@ -1,6 +1,6 @@
 BUILD_DIR=$(CURDIR)/build
 COVERAGE_DIR=$(BUILD_DIR)/coverage
-BEATS?=auditbeat filebeat heartbeat journalbeat metricbeat packetbeat winlogbeat x-pack/functionbeat
+BEATS?=auditbeat filebeat heartbeat journalbeat metricbeat packetbeat winlogbeat x-pack/functionbeat x-pack/agent
 PROJECTS=libbeat $(BEATS)
 PROJECTS_ENV=libbeat filebeat metricbeat
 PYTHON_ENV?=$(BUILD_DIR)/python-env

dev-tools/packaging/packages.yml

@@ -55,10 +55,10 @@ shared:
         template: '{{ elastic_beats_dir }}/dev-tools/packaging/templates/{{.PackageType}}/init.sh.tmpl'
         mode: 0755
       /etc/{{.BeatName}}/beats/filebeat-{{ beat_version }}-{{.GOOS}}-{{.AgentArchName}}.tar.gz:
-        source: '{{ elastic_beats_dir }}/x-pack/filebeat/build/distributions/filebeat-{{ beat_version }}-{{.GOOS}}-{{.AgentArchName}}.tar.gz'
+        source: '{{ elastic_beats_dir }}/x-pack/filebeat/build/distributions/filebeat-{{ beat_version }}{{if .Snapshot}}-SNAPSHOT{{end}}-{{.GOOS}}-{{.AgentArchName}}.tar.gz'
         mode: 0644
       /etc/{{.BeatName}}/beats/metricbeat-{{ beat_version }}-{{.GOOS}}-{{.AgentArchName}}.tar.gz:
-        source: '{{ elastic_beats_dir }}/x-pack/metricbeat/build/distributions/metricbeat-{{ beat_version }}-{{.GOOS}}-{{.AgentArchName}}.tar.gz'
+        source: '{{ elastic_beats_dir }}/x-pack/metricbeat/build/distributions/metricbeat-{{ beat_version }}{{if .Snapshot}}-SNAPSHOT{{end}}-{{.GOOS}}-{{.AgentArchName}}.tar.gz'
         mode: 0644
 
 
@@ -98,10 +98,10 @@ shared:
         mode: 0600
         config: true
       /etc/{{.BeatName}}/beats/filebeat-{{ beat_version }}-{{.GOOS}}-{{.AgentArchName}}.tar.gz:
-        source: '{{ elastic_beats_dir }}/x-pack/filebeat/build/distributions/filebeat-{{ beat_version }}-{{.GOOS}}-{{.AgentArchName}}.tar.gz'
+        source: '{{ elastic_beats_dir }}/x-pack/filebeat/build/distributions/filebeat-{{ beat_version }}{{if .Snapshot}}-SNAPSHOT{{end}}-{{.GOOS}}-{{.AgentArchName}}.tar.gz'
         mode: 0644
       /etc/{{.BeatName}}/beats/metricbeat-{{ beat_version }}-{{.GOOS}}-{{.AgentArchName}}.tar.gz:
-        source: '{{ elastic_beats_dir }}/x-pack/metricbeat/build/distributions/metricbeat-{{ beat_version }}-{{.GOOS}}-{{.AgentArchName}}.tar.gz'
+        source: '{{ elastic_beats_dir }}/x-pack/metricbeat/build/distributions/metricbeat-{{ beat_version }}{{if .Snapshot}}-SNAPSHOT{{end}}-{{.GOOS}}-{{.AgentArchName}}.tar.gz'
         mode: 0644
 
   - &agent_binary_files
@@ -132,10 +132,10 @@ shared:
     files:
       <<: *agent_binary_files
       'beats/filebeat-{{ beat_version }}-{{.GOOS}}-{{.AgentArchName}}.tar.gz':
-        source: '{{ elastic_beats_dir }}/x-pack/filebeat/build/distributions/filebeat-{{ beat_version }}-{{.GOOS}}-{{.AgentArchName}}.tar.gz'
+        source: '{{ elastic_beats_dir }}/x-pack/filebeat/build/distributions/filebeat-{{ beat_version }}{{if .Snapshot}}-SNAPSHOT{{end}}-{{.GOOS}}-{{.AgentArchName}}.tar.gz'
         mode: 0644
       'beats/metricbeat-{{ beat_version }}-{{.GOOS}}-{{.AgentArchName}}.tar.gz':
-        source: '{{ elastic_beats_dir }}/x-pack/metricbeat/build/distributions/metricbeat-{{ beat_version }}-{{.GOOS}}-{{.AgentArchName}}.tar.gz'
+        source: '{{ elastic_beats_dir }}/x-pack/metricbeat/build/distributions/metricbeat-{{ beat_version }}{{if .Snapshot}}-SNAPSHOT{{end}}-{{.GOOS}}-{{.AgentArchName}}.tar.gz'
         mode: 0644
 
   # Binary package spec (zip for windows) for community beats.
@@ -150,10 +150,10 @@ shared:
         template: '{{ elastic_beats_dir }}/dev-tools/packaging/templates/windows/uninstall-service.ps1.tmpl'
         mode: 0755
       'beats/filebeat-{{ beat_version }}-{{.GOOS}}-{{.AgentArchName}}.zip':
-        source: '{{ elastic_beats_dir }}/x-pack/filebeat/build/distributions/filebeat-{{ beat_version }}-{{.GOOS}}-{{.AgentArchName}}.zip'
+        source: '{{ elastic_beats_dir }}/x-pack/filebeat/build/distributions/filebeat-{{ beat_version }}{{if .Snapshot}}-SNAPSHOT{{end}}-{{.GOOS}}-{{.AgentArchName}}.zip'
         mode: 0644
       'beats/metricbeat-{{ beat_version }}-{{.GOOS}}-{{.AgentArchName}}.zip':
-        source: '{{ elastic_beats_dir }}/x-pack/metricbeat/build/distributions/metricbeat-{{ beat_version }}-{{.GOOS}}-{{.AgentArchName}}.zip'
+        source: '{{ elastic_beats_dir }}/x-pack/metricbeat/build/distributions/metricbeat-{{ beat_version }}{{if .Snapshot}}-SNAPSHOT{{end}}-{{.GOOS}}-{{.AgentArchName}}.zip'
         mode: 0644
 
   - &agent_docker_spec