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17 Jul 2018 Install HAProxy 1.8 on CentOS 7

HaproxyThis is just a short write-up on installing HAProxy version 1.8 on CentOS 7 using Software Collections. HAProxy  is an application layer (Layer 7) load balancing and high availability solution that you can use to implement a reverse proxy for HTTP and TCP-based Internet services. I am using it to expose my webservices through a reverse proxy.

If default HAProxy version 1.5 is installed then it should be removed because it is blocking the new version we are going to install.

# yum remove haproxy
...
warning: /etc/haproxy/haproxy.cfg saved as /etc/haproxy/haproxy.cfg.rpmsave
...

This warning indicates that your old HAProxy config file is renamed. This is useful to know if you are planning to use the same file in HAProxy version 1.8.

Install the Software Collections (SCL) repository to get access to the new HAProxy version

# yum install centos-release-scl

Update your repositories and accept the new repository.

Installing HAProxy 1.8

# yum install rh-haproxy18-haproxy rh-haproxy18-haproxy-syspaths

The rh-haproxy18-haproxy-syspaths package is a system-wide wrapper for the rh-haproxy18-haproxy package and allows us to run HAProxy 1.8 as a service. This package conflicts with the HAProxy and cannot be installed on one system.

If we now look in /etc/haproxy/haproxy.cfg we will see that the config file is a symling to the new package

# ls -l /etc/haproxy/
lrwxrwxrwx. 1 root root 44 Jul 17 18:19 haproxy.cfg -> /etc/opt/rh/rh-haproxy18/haproxy/haproxy.cfg

If you had HAProxy 1.5 installed previously and would like to continue using the config file, copy it to the new location. First we preserve the original HAProxy 1.8 config file by renaming it or just copy the rules that you need from the old config.

# mv /etc/opt/rh/rh-haproxy18/haproxy/haproxy.cfg /etc/opt/rh/rh-haproxy18/haproxy/haproxy.cfg.original
# cp /etc/haproxy/haproxy.cfg.rpmsave /etc/opt/rh/rh-haproxy18/haproxy/haproxy.cfg

We are now ready to start HAProxy 1.8 with our old config file

# systemctl start rh-haproxy18-haproxy
# systemctl status rh-haproxy18-haproxy

If we would like to have the new HAProxy version to auto-start on reboot

# systemctl enable rh-haproxy18-haproxy

Done.

Installing HAProxy 1.8 on RedHat 7 is similar, except you use subscription-manager and add the software collections repository.

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02 Mar 2018 Configure VLAN on top of network team using nmcli / NetworkManager

This post is almost similar as the previous where I created a team with two network nics as members using NetworkManager nmcli from a console. This time I have added a VLAN on top of my LACP network team with two member nics.

First we need to install the teamd package if it is not already installed.

# yum install teamd

Using the console command nmcli and NetworkManager and a json-config file with the default config for the team, filename team-master-conf.json:

{
        "runner":       {
                "active": true,
                "fast_rate": true,
                "name": "lacp",
                "tx_hash": [ "eth", "ipv4" ]
        },
        "tx_balancer":  { "name": "basic" },
        "link_watch":   { "name": "ethtool" }
}
# nmcli con add type team con-name team0 ifname team0 config team-master-conf.json
# nmcli con add type team-slave con-name team0-em1 ifname em1 master team0
# nmcli con add type team-slave con-name team0-em2 ifname em2 master team0

I have not added an IP-address to the new team since I will add that on the VLAN interface.

Check the status of the team

# nmcli con status
NAME               UUID                                  TYPE            DEVICE
team0              7f0c0038-b8c1-45bb-a286-501d02304700  team            team0
team0-em1          0394e2ae-6610-4997-92db-775876866d0d  802-3-ethernet  em1
team0-em2          7050d641-83bb-497a-ae23-6af029386117  802-3-ethernet  em2

Check the state of the team

# teamdctl team0 state
setup:
  runner: lacp
ports:
  em1
    link watches:
      link summary: up
      instance[link_watch_0]:
        name: ethtool
        link: up
        down count: 1
    runner:
      aggregator ID: 12, Selected
      selected: yes
      state: current
  em2
    link watches:
      link summary: up
      instance[link_watch_0]:
        name: ethtool
        link: up
        down count: 0
    runner:
      aggregator ID: 12, Selected
      selected: yes
      state: current
runner:
  active: yes
  fast rate: yes

Add a VLAN to the network team

# nmcli con add type vlan con-name team0-vlan12 dev team0 id 12 ip4 10.1.0.20/24 gw4 10.1.0.1

The new config looks like this

# nmcli con s | grep team
team0              7f0c0038-b8c1-45bb-a286-501d02304700  team            team0
team0-vlan12       d5de0d83-d490-4535-915c-4cbdcf39830b  vlan            team0.12
team0-em1          0394e2ae-6610-4997-92db-775876866d0d  802-3-ethernet  em1
team0-em2          7050d641-83bb-497a-ae23-6af029386117  802-3-ethernet  em2

This config is confirmed working on RHEL 7.4 and Centos.
I assume the switch is configured as needed before starting this config on the server.

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02 Mar 2018 Configure network team using nmcli / NetworkManager

This is a short post on how to create a LACP network team with two member nics using NetworkManager and nmcli. Configuring av network team is very similar to creating a bond.

First we need to install the teamd package if it is not already installed.

# yum install teamd

I have also included a json-config file with the default config for the team, filename team-master-conf.json:

{
        "runner":       {
                "active": true,
                "fast_rate": true,
                "name": "lacp",
                "tx_hash": [ "eth", "ipv4" ]
        },
        "tx_balancer":  { "name": "basic" },
        "link_watch":   { "name": "ethtool" }
}
# nmcli con add type team con-name team0 ifname team0 config team-master-conf.json ip4 10.0.0.10/24 gw4 10.0.0.1
# nmcli con add type team-slave con-name team0-em1 ifname em1 master team0
# nmcli con add type team-slave con-name team0-em2 ifname em2 master team0

Check the status of the team

# nmcli con status
NAME               UUID                                  TYPE            DEVICE
team0              7f0c0038-b8c1-45bb-a286-501d02304700  team            team0
team0-em1          0394e2ae-6610-4997-92db-775876866d0d  802-3-ethernet  em1
team0-em2          7050d641-83bb-497a-ae23-6af029386117  802-3-ethernet  em2

Check the state of the team

# teamdctl team0 state
setup:
  runner: lacp
ports:
  em1
    link watches:
      link summary: up
      instance[link_watch_0]:
        name: ethtool
        link: up
        down count: 1
    runner:
      aggregator ID: 12, Selected
      selected: yes
      state: current
  em2
    link watches:
      link summary: up
      instance[link_watch_0]:
        name: ethtool
        link: up
        down count: 0
    runner:
      aggregator ID: 12, Selected
      selected: yes
      state: current
runner:
  active: yes
  fast rate: yes

Some NetworkManager basics

Take down a network interface

# nmcli con down em1

Take up a network interface

# nmcli con up em1

Delete a network interface

# nmcli con delete em1

Add a new network device

# nmcli con add em1

This config is confirmed working on RHEL 7.4 and Centos.

I assume the switch is configured as needed before starting this config on the server.

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12 Jan 2018 Exclude certain packages from yum-cron (but not from yum)

This is a solution for how you can exclude certain packages being updated when using yum-cron.
Docker and kernel are packages I would like to exclude from yum-cron.

The solution to this is to modify the /etc/yum/yum-cron.conf file adding this to the [base] section

RHEL7/Centos7

[base]
...
exclude = kernel* docker*

On RHEL6/Centos6 you can use the YUM_PARAMETER to do the same thing

YUM_PARAMETER=kernel* docker*

If you would like to exclude certain packages from yum alltogether you need to modify the affected yum repository.
Example to permanently exclude certain packages like Docker from being updated using the yum command/CLI

RHEL7
Modify /etc/yum.repos.d/redhat.repo

Add the following line under [rhel-7-server-extras-rpms]
exclude = docker*

Before adding a exclude command verify that you add the exclude line under the right repository.
Example

# yum info docker

From repo : rhel-7-server-extras-rpms

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24 Jun 2015 Mount Samba share using gvfs-mount as normal user

This is just a shot note on how to mount a Samba or Windows CIFS share as a normal linux user using the gvfs-mount command in Centos 7 or RedHat 7.

Mounting a mountpoint share using the username user and password
[user@host] gvfs-mount smb://username@192.168.0.200/shared-folder

If the command finishes without any errors you can now access your smb mount on the following path

[user@host] ls -l /run/user/1000/gvfs/smb-share\:server\=192.168.0.200\,share\=shared-folder\,user\=username/

1000 corresponds to your users id and can be determined by the id command

[user@host] id
uid=1000(username) gid=1000(username) groups=1000(username)

PS
I compared the performance between connecting directly to a Samba share using UNC path and using gvfs-mount and saw that there is a noticeable speed decrease using gvfs-mount.
But if you have old software that does not support UNC path, then gvfs-mount is a good alternative to no access.

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