Add process_agent.build_docker_agent task (#4627)

Adds a process_agent.build_docker_agent which can be used to quickly build a docker image containing custom builds of the system-probe and process-agent. This is useful for in container environments.

tasks/process_agent.py

@@ -3,8 +3,10 @@
 import re
 import shutil
 import sys
-
+import shutil
+import tempfile
 from invoke import task
+from invoke.exceptions import Exit
 from subprocess import check_output
 
 from .utils import bin_name, get_gopath, get_build_flags, REPO_PATH, get_version, get_git_branch_name, get_go_version, get_git_commit, get_version_numeric_only
@@ -96,3 +98,42 @@ def build(ctx, race=False, go_version=None, incremental_build=False,
     }
 
     ctx.run(cmd.format(**args), env=env)
+
+
+@task
+def build_dev_image(ctx, image=None, push=False, base_image="datadog/agent:latest"):
+    """
+    Build a dev image of the process-agent based off an existing datadog-agent image
+
+    image: the image name used to tag the image
+    push: if true, run a docker push on the image
+    base_image: base the docker image off this already build image (default: datadog/agent:latest)
+    """
+    if image is None:
+        raise Exit(message="image was not specified")
+
+    with TempDir() as docker_context:
+        ctx.run("cp tools/ebpf/Dockerfiles/Dockerfile-process-agent-dev {to}".format(
+            to=docker_context + "/Dockerfile"))
+
+        ctx.run("cp bin/process-agent/process-agent {to}".format(
+            to=docker_context + "/process-agent"))
+
+        ctx.run("cp bin/system-probe/system-probe {to}".format(
+            to=docker_context + "/system-probe"))
+
+        with ctx.cd(docker_context):
+            ctx.run("docker build --tag {image} --build-arg AGENT_BASE={base_image} .".format(image=image, base_image=base_image))
+
+    if push:
+        ctx.run("docker push {image}".format(image=image))
+
+
+class TempDir():
+    def __enter__(self):
+        self.fname = tempfile.mkdtemp()
+        print("created tempdir: {name}".format(name=self.fname))
+        return self.fname
+    def __exit__(self, exception_type, exception_value, traceback):
+        print("deleting tempdir: {name}".format(name=self.fname))
+        shutil.rmtree(self.fname)

tools/ebpf/Dockerfiles/Dockerfile-process-agent-dev

@@ -0,0 +1,11 @@
+ARG AGENT_BASE=datadog/agent:latest
+FROM $AGENT_BASE
+
+# include some useful dev tools since this will be used or development
+RUN apt-get update -y && apt-get install -y jq conntrack netcat dnsutils
+
+# inv -e process-agent.build-dev-image will set up a temporary
+# build directory where this Dockerfile and the necessary binaries
+# are in the same directory
+COPY process-agent /opt/datadog-agent/embedded/bin/process-agent
+COPY system-probe /opt/datadog-agent/embedded/bin/system-probe