Allow diagnostics to be downloaded on port 62374

A client like `pinata diagnose` can do the equivalent of:

  nc 192.168.64.2 62374 > foo.tar

and find `foo.tar` contains

- the output of `/usr/bin/diagnostics`
- `iptables -L`
- `netstat -an`
- `ps uax`
- `docker ps`
- `dig docker.com`
- `wget http://docker.com`

This will allow us to diagnose various in-VM faults, without having
to ask the user to access the console and run commands.

Signed-off-by: David Scott <dave.scott@docker.com>

alpine/Dockerfile

@@ -34,6 +34,8 @@ COPY packages/docker/docker /usr/bin/
 COPY packages/docker/etc /etc/
 COPY packages/docker-x/docker-x /usr/bin/
 COPY packages/diagnostics/diagnostics /usr/bin/
+COPY packages/diagnostics/diagnostics-server /usr/bin/
+COPY packages/diagnostics/diagnostics-download /usr/bin/
 COPY packages/diagnostics/etc /etc/
 COPY packages/automount/etc /etc/
 COPY packages/9pinit/etc /etc/

alpine/packages/diagnostics/diagnostics-download

@@ -0,0 +1,20 @@
+#!/bin/sh
+
+# Gather diagnostic data and write a .tar file to stdout
+
+TEMP=$(mktemp -d diagnoseXXXXXXX)
+trap 'rm -rf "$TEMP"' EXIT
+cd $TEMP
+
+# gather diagnostic data
+ps uax > "ps -aux"
+netstat -an > "netstat -an"
+iptables -L > "iptables -L"
+dmesg > dmesg
+timeout -t 2 docker ps > "docker ps"
+/usr/bin/diagnostics > "diagnostics"
+dig docker.com > "dig docker.com"
+wget -O - http://www.docker.com/ &> "wget docker.com"
+
+# send everything to the client
+tar -c .

alpine/packages/diagnostics/diagnostics-server

@@ -0,0 +1,7 @@
+#!/bin/sh
+
+# Allow clients (e.g. pinata diagnose) to download diagnostic data
+
+while /bin/true; do
+	nc -l -p 62374 -e /usr/bin/diagnostics-download 2>> /var/log/diagnostics-server.log
+done

alpine/packages/diagnostics/etc/init.d/diagnostics

@@ -10,4 +10,5 @@ start()
 	ebegin "Checking system state"
 
 	/usr/bin/diagnostics
+	/usr/bin/diagnostics-server &
 }