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Create a systemd unit and scripts in order to automatize a lxc mailserver container launch
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Authored by Sandlayth on Dec 9 2015, 18:56.
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Details

Summary

The mail server is isolated into a lxc container. We want this mail server to be operational at startup

This requires two tasks:

  • start the container mailserver through lxc-start
  • add to iptables rules for NAT forwarding

We also provide a stop script to clean iptables.

Resolves T466.

Test Plan

To evaluate the container status, we used 3 ways:

  • try a telnet connection from an external server to see if the SMTP server (see below)
  • lxc-top
  • iptables -L | grep 10.0.3.8 (the IP of the mailserver container)

It has also been tested in Dwellers through systemd and works.

$ telnet -4 dwellers.nasqueron.org 25

Trying 212.129.32.223...
Connected to dwellers.nasqueron.org.
Escape character is '^]'.
220 mail.nasqueron.org ESMTP Postfix (Debian/GNU)

Diff Detail

Repository
rOPS Nasqueron Operations
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Event Timeline

Sandlayth retitled this revision from to [WIP] Create a systemd unit and scripts in order to automatize a lxc mailserver container launch.
Sandlayth updated this object.
Sandlayth edited the test plan for this revision. (Show Details)
Sandlayth added a reviewer: dereckson.
Sandlayth added subscribers: dereckson, Sandlayth.

Comments in lxc_start apply also for lxc_stop.

roles/mailserver/systemd-unit/files/lxc-containers.service
2 ↗(On Diff #234)

The description of a systemd unit is the service provided, not an action.

For example this description currently leads to the following journal entries:

Dec 09 12:55:13 dwellers.nasqueron.org systemd[1]: Stopped Launch lxc mailserver container.
Dec 09 12:56:16 dwellers.nasqueron.org systemd[1]: Starting Launch lxc mailserver container...
7 ↗(On Diff #234)

Here we should be coherent with other existing stuff. In a previous systemd task, we wrote a docker-container-status script.

I would suggest here lxc-container-mailserver-start and lxc-container-mailserver stop

roles/mailserver/systemd-unit/files/lxc_start
1 ↗(On Diff #234)

Use sh anytime bash is not required.

8 ↗(On Diff #234)

Container name should be a variable. $CONTAINER_NAME for example.

10 ↗(On Diff #234)

Both Dwellers and mailserver container IPs should be variables, ens192 too.

$IPTABLES -t nat -I PREROUTING -i $HOST_INTERFACE -p TCP -d $HOST_IP/32 --dport 25 -j DNAT --to-destination $CONTAINER_IP:25

11 ↗(On Diff #234)

This one is tricky, so let's keep as it (but store the 21080 in a $WEB_PORT variable).

For the others rules, we can use a for loop.

See http://www.tutorialspoint.com/unix/unix-loop-control.htm for implementation example.

dereckson requested changes to this revision.Dec 9 2015, 21:52
dereckson edited edge metadata.

Good work, the systemd unit works well.

Commit message

Commit first line should be shorter. Then, use paragraphs, not a sentence starting by a lowercase.

Code review

See inline comments.

This revision now requires changes to proceed.Dec 9 2015, 21:52
Sandlayth edited edge metadata.
  • Create a systemd unit and scripts in order to automatize a lxc mailserver container launch
dereckson retitled this revision from [WIP] Create a systemd unit and scripts in order to automatize a lxc mailserver container launch to Create a systemd unit and scripts in order to automatize a lxc mailserver container launch.Dec 16 2015, 10:36
dereckson updated this object.
dereckson edited the test plan for this revision. (Show Details)
dereckson edited edge metadata.
dereckson requested changes to this revision.Dec 16 2015, 10:45
dereckson edited edge metadata.

Nickel.

Some last details.

roles/mailserver/systemd-unit/files/lxc-container-mailserver-stop
14

As we have absolutely everything else configurable, we could add docker0 and 21080 here too.

16

This is not a web port. They match SMTP, IMAP or POP mail servers.

26

Same here, just PORT would be fine.

roles/mailserver/systemd-unit/files/lxc-container-mailserver.service
3

extraneous space

This is THE string to bring some love to in systemd, as it's the string used in the journal.

First, the description starts with an uppercase according https://coreos.com/docs/launching-containers/launching/getting-started-with-systemd/ and http://www.freedesktop.org/software/systemd/man/systemd.service.html.

Then, I wonder if we shouldn't hide low-level implementation details.

If so: Description=Mail server

If a more low-level is deemed more valuable:

Description=LXC mail server container

This revision now requires changes to proceed.Dec 16 2015, 10:45
Sandlayth edited edge metadata.
Sandlayth updated this object.
  • Create a systemd unit and scripts in order to automatize a lxc mailserver container launch

Add variables for docker network interface, and nginx port.

Replacing WEB_PORT variables by PORT ; indeed it store also mail ports

Sandlayth edited edge metadata.
  • Create a systemd unit and scripts in order to automatize a lxc mailserver container launch
  • Create a systemd unit and scripts in order to automatize a lxc mailserver container launch

Fix extra space.

dereckson requested changes to this revision.Dec 16 2015, 12:03
dereckson edited edge metadata.

Read again the comment about the systemd description, it should not start by lowercase.

This revision now requires changes to proceed.Dec 16 2015, 12:03
Sandlayth edited edge metadata.
  • Create a systemd unit and scripts in order to automatize a lxc mailserver container launch

Adding capital letter

dereckson edited edge metadata.

Okay, that runs the following commands:

Start script

/usr/bin/lxc-start -n mailserver -d
/usr/sbin/iptables -t nat -I PREROUTING -i ens192 -p TCP -d 212.129.32.223/32 --dport 25 -j DNAT --to-destination 10.0.3.8:25
/usr/sbin/iptables -t nat -I PREROUTING -i ens192 -p TCP -d 212.129.32.223/32 --dport 110 -j DNAT --to-destination 10.0.3.8:110
/usr/sbin/iptables -t nat -I PREROUTING -i ens192 -p TCP -d 212.129.32.223/32 --dport 143 -j DNAT --to-destination 10.0.3.8:143
/usr/sbin/iptables -t nat -I PREROUTING -i ens192 -p TCP -d 212.129.32.223/32 --dport 465 -j DNAT --to-destination 10.0.3.8:465
/usr/sbin/iptables -t nat -I PREROUTING -i ens192 -p TCP -d 212.129.32.223/32 --dport 587 -j DNAT --to-destination 10.0.3.8:587
/usr/sbin/iptables -t nat -I PREROUTING -i ens192 -p TCP -d 212.129.32.223/32 --dport 21080 -j DNAT --to-destination 10.0.3.8:80
/usr/sbin/iptables -t nat -I PREROUTING -i docker0 -p TCP -d 212.129.32.223/32 --dport 25 -j DNAT --to-destination 10.0.3.8:25
/usr/sbin/iptables -t nat -I PREROUTING -i docker0 -p TCP -d 212.129.32.223/32 --dport 143 -j DNAT --to-destination 10.0.3.8:143
/usr/sbin/iptables -t nat -I PREROUTING -i docker0 -p TCP -d 212.129.32.223/32 --dport 465 -j DNAT --to-destination 10.0.3.8:465
/usr/sbin/iptables -t nat -I PREROUTING -i docker0 -p TCP -d 212.129.32.223/32 --dport 587 -j DNAT --to-destination 10.0.3.8:587

Stop script

/usr/sbin/iptables -t nat -D PREROUTING -i ens192 -p TCP -d 212.129.32.223/32 --dport 25 -j DNAT --to-destination 10.0.3.8:25
/usr/sbin/iptables -t nat -D PREROUTING -i ens192 -p TCP -d 212.129.32.223/32 --dport 110 -j DNAT --to-destination 10.0.3.8:110
/usr/sbin/iptables -t nat -D PREROUTING -i ens192 -p TCP -d 212.129.32.223/32 --dport 143 -j DNAT --to-destination 10.0.3.8:143
/usr/sbin/iptables -t nat -D PREROUTING -i ens192 -p TCP -d 212.129.32.223/32 --dport 465 -j DNAT --to-destination 10.0.3.8:465
/usr/sbin/iptables -t nat -D PREROUTING -i ens192 -p TCP -d 212.129.32.223/32 --dport 587 -j DNAT --to-destination 10.0.3.8:587
/usr/sbin/iptables -t nat -D PREROUTING -i ens192 -p TCP -d 212.129.32.223/32 --dport 21080 -j DNAT --to-destination 10.0.3.8:80
/usr/sbin/iptables -t nat -D PREROUTING -i docker0 -p TCP -d 212.129.32.223/32 --dport 25 -j DNAT --to-destination 10.0.3.8:25
/usr/sbin/iptables -t nat -D PREROUTING -i docker0 -p TCP -d 212.129.32.223/32 --dport 143 -j DNAT --to-destination 10.0.3.8:143
/usr/sbin/iptables -t nat -D PREROUTING -i docker0 -p TCP -d 212.129.32.223/32 --dport 465 -j DNAT --to-destination 10.0.3.8:465
/usr/sbin/iptables -t nat -D PREROUTING -i docker0 -p TCP -d 212.129.32.223/32 --dport 587 -j DNAT --to-destination 10.0.3.8:587
/usr/bin/lxc-stop -n mailserver

Looks good to me.

This revision is now accepted and ready to land.Dec 16 2015, 13:49
This revision was automatically updated to reflect the committed changes.