Johan's questions

I have a server on my network and I would like to use that one to pretend to be many different servers.

The physical pc is running a Ubuntu server and when connected to the network the dhcp server gives that server ip number 192.168.1.10.

Then inside of that it is fairly easy to start many different docker images and to avoid collisions on ports I can give the services non standard port numbers. However that is not very user friendly for the other users on the network.

It would be more user friendly to expose each docker image with it's own ip-number.

Let's therefore try to describe a typical usecase, where this server would host both a gitlab and a jenkins master.

This setup is possible with VirtualBox when the virtual servers uses "bridged adapters", however I'm struggling to do the same but with dockers instead. (Please note that I don't want to use VirtualBox for this since it eats so much resources compared with docker).

From my basic understading of docker, it seems like I need to create a couple of virtual docker networks, however I can't figure out if those should be "bridge", "macvlan" or similar to create this.

What I have tried are for example to create 2 bridged networks in on the host ubuntu server

First we have the default network

enp0s31f6 Link encap:Ethernet  HWaddr 54:bf:64:96:51:57  
          inet addr:192.168.1.10  Bcast:192.168.1.255  Mask:255.255.255.0
          inet6 addr: fdac:b176:f48b:0:c9bf:3d46:a9f6:8a08/64 Scope:Global
          inet6 addr: fe80::6f2:9b6e:b8a4:225/64 Scope:Link
          inet6 addr: fdac:b176:f48b:0:de76:744c:f42a:75e1/64 Scope:Global
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:1356 errors:0 dropped:0 overruns:0 frame:0
          TX packets:842 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:152299 (152.2 KB)  TX bytes:63753 (63.7 KB)
          Interrupt:16 Memory:ef500000-ef520000 

Then I find the one that docker created:

docker0   Link encap:Ethernet  HWaddr 02:42:b1:ff:6e:89  
          inet addr:172.17.0.1  Bcast:172.17.255.255  Mask:255.255.0.0
          inet6 addr: fe80::42:b1ff:feff:6e89/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:4372 errors:0 dropped:0 overruns:0 frame:0
          TX packets:4665 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0 
          RX bytes:175876 (175.8 KB)  TX bytes:333163 (333.1 KB)

And then I created bridge11 for the .11 and bridge12 for .12

bridge11  Link encap:Ethernet  HWaddr 4a:2b:6b:07:51:70  
          inet addr:192.168.1.11  Bcast:192.168.1.255  Mask:255.255.255.0
          UP BROADCAST MULTICAST  MTU:1500  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:0 (0.0 B)  TX bytes:0 (0.0 B)

bridge12  Link encap:Ethernet  HWaddr 82:ec:66:9c:f2:b5  
          inet addr:192.168.1.12  Bcast:192.168.1.255  Mask:255.255.255.0
          UP BROADCAST MULTICAST  MTU:1500  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:9 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:0 (0.0 B)  TX bytes:828 (828.0 B)

However when I try to start a vanilla gitlab docker image with the .12 network

docker run \
    --name gitlab \
    --hostname gitlab \
    --publish 192.168.1.12:443:443 \
    --publish 192.168.1.12:80:80 \
    --publish 192.168.1.12:22:22 \
    --volume /var/gitlab/config:/etc/gitlab:Z \
    --volume /var/gitlab/logs:/var/log/gitlab:Z \
    --volume /var/gitlab/data:/var/opt/gitlab:Z \
    gitlab/gitlab-ce:latest

Then he complains that port 22 is already in use like this:

docker: Error response from daemon: 
  driver failed programming external connectivity on endpoint gitlab 
  (4fda91298a6b9d416cb7e91813d95ad0d35315260881377d1238887724cf3d1f): 
  Error starting userland proxy: listen tcp 192.168.1.12:22: 
  bind: address already in use.
ERRO[0000] error waiting for container: context canceled 

Please note that port 22 is in use on 192.168.1.10 not on 192.168.1.12, and if I use another unused port, that actually works.

However my idea was to be able to reuse things like the standard ssh port on different docker images.

I am about to buy and install a 802.3af PoE switch (probably a NETGEAR ProSafe FS728TP) that will power some Arduinos with PoE ethernet shields that is also 802.3af.

How future safe is this?

Let's say that I in the future would like to install some surveillance cameras (PoE powered) on this network do they need to be 802.3af or will newer clients with PoE versions like 802.3at also work?

I have a old pc that is running Debian stable, that is in need of a upgrade. The problem is that it is using latin1 (ISO-8859-1) for everything, and since the rest of the world has moved to UTF-8 I plan to convert this computer as well.

And for this question I will focus in on the files that are served with Samba, and some has some latin1 characters in the filenames (like åäö).

Now my plan is to move all data of this old computer onto and a brand new one that is running Debian stable (but with UTF-8).

Does anybody have a good idea?

Note: later I plan to use iconv to convert the content of some files with something like this:

iconv --from-code=ISO-8859-1 --to-code=UTF-8 iso.txt > utf.txt

However I don't know of a good way to convert the filesystem it self.

Note: Normally I usally just scp from one computer to the next, but then I end up with latin1 characters in the utf-8 filesystem.

Update: Did a small test round with a hand full of files (with funny chars) in the filenames, and that seemed like it could work.

convmv -r -f ISO-8859-1 -t UTF-8  *

Note: -r = recursive; -f/-t = from/to.

So it was only to execute with the --notest

convmv -r -f ISO-8859-1 -t UTF-8 --notest *

Nothing more to it.

What is the best way to do Subversion backups (on a Debian based server).

Is it to use svnadmin?

svnadmin dump /path/to/reponame > reponame.dump

Or maybe just to tar the dir where the repositories are?

tar -cvzf svn.backup.tar.gz /var/subversion/

What are the pros and cons of the above?

Thanks Johan

Update: This is a small server with only a handful of repos. So incremental backups are probably not needed, I think it is better to focus on keeping it simple.

Update: I used packs wrapper script (that in turn was a wrapper for svn-hot-backup) to do a full backup and then did a full recovery on another clean computer. However I removed that "SVN_HOTBACKUP_NUM_BACKUPS=10" part since it was not working for me.

Please note that I feel it was kind of simple and the result was very close to just tar the dir. But as Manni pointed out here to use svn-hot-backup/"svnadmin hotcopy" is a more reliable method, since tar could create corrupt backups from time to time if you are unlucky.