From bd371392faa56b6b38098c067e8113cc149e6b4a Mon Sep 17 00:00:00 2001
From: Charly Fontaine <charly@datadoghq.com>
Date: Fri, 23 Feb 2018 06:37:24 -0500
Subject: [PATCH] remove finish script avoiding s6 nuke (#1337)

---
 Dockerfiles/agent/Dockerfile                       |  3 +++
 Dockerfiles/agent/init-stage3                      | 14 ++++++++++++++
 Dockerfiles/agent/s6-services/agent/finish         |  4 +++-
 .../dockerfile-pid-host-47ddbf2cdfa6e02e.yaml      |  5 +++++
 4 files changed, 25 insertions(+), 1 deletion(-)
 create mode 100755 Dockerfiles/agent/init-stage3
 create mode 100644 releasenotes/notes/dockerfile-pid-host-47ddbf2cdfa6e02e.yaml

diff --git a/Dockerfiles/agent/Dockerfile b/Dockerfiles/agent/Dockerfile
index ec47e665f5bd1..4c24ca56ae1f7 100644
--- a/Dockerfiles/agent/Dockerfile
+++ b/Dockerfiles/agent/Dockerfile
@@ -80,6 +80,9 @@ COPY s6-services /etc/services.d/
 COPY entrypoint /etc/cont-init.d/
 COPY probe.sh initlog.sh /
 
+# Override the exit script by ours to fix --pid=host operations
+COPY init-stage3 /etc/s6/init/init-stage3
+
 # Prepare for running without root
 RUN adduser --group dd-agent \
  && adduser --system --no-create-home --disabled-password --ingroup dd-agent dd-agent \
diff --git a/Dockerfiles/agent/init-stage3 b/Dockerfiles/agent/init-stage3
new file mode 100755
index 0000000000000..4eff9e6544565
--- /dev/null
+++ b/Dockerfiles/agent/init-stage3
@@ -0,0 +1,14 @@
+#!/bin/execlineb -S0
+
+# This is the shutdown script, running as process 1.
+cd /
+
+# Merge environments from our custom stage into current context
+s6-envdir -I /var/run/s6/env-stage3
+
+# Reap all the zombies, and we're done.
+wait { }
+
+# Use CMD exit code defaulting to zero if not present.
+importas -u -D0 S6_STAGE2_EXITED S6_STAGE2_EXITED
+exit ${S6_STAGE2_EXITED}
diff --git a/Dockerfiles/agent/s6-services/agent/finish b/Dockerfiles/agent/s6-services/agent/finish
index 806bff20c55b7..1c1d48edf12a6 100755
--- a/Dockerfiles/agent/s6-services/agent/finish
+++ b/Dockerfiles/agent/s6-services/agent/finish
@@ -3,4 +3,6 @@
 # Kill the container if the main agent were to exit
 
 foreground { /initlog.sh "AGENT EXITED WITH CODE ${1}, SIGNAL ${2}, KILLING CONTAINER" }
-s6-svscanctl -t /var/run/s6/services
+
+# If the container is stopped via docker, s6 is already closing, silencing the error
+redirfd -w 2 /dev/null s6-svscanctl -t /var/run/s6/services
diff --git a/releasenotes/notes/dockerfile-pid-host-47ddbf2cdfa6e02e.yaml b/releasenotes/notes/dockerfile-pid-host-47ddbf2cdfa6e02e.yaml
new file mode 100644
index 0000000000000..a9d41e0dc7c99
--- /dev/null
+++ b/releasenotes/notes/dockerfile-pid-host-47ddbf2cdfa6e02e.yaml
@@ -0,0 +1,5 @@
+---
+fixes:
+  - |
+    Fix Docker container `--pid=host` operations. Previous RCs can cause host system
+    instabilities and should not be run in pid host mode.