Install Semaphore Ansible Web UI on CentOS 7|CentOS 8

In this guide, we will install Semaphore Ansible Web UI on CentOS 7|CentOS 8. Semaphore is an open source web-based solution that makes Ansible easy to use for IT teams of all kinds. It gives you a Web interface from where you can launch and manage Ansible Tasks.

Install Semaphore Ansible Web UI on CentOS 7|CentOS 8

Semaphore depends on the following tools:

MySQL >= 5.6.4/MariaDB >= 5.3
ansible
git >= 2.x

We will start the installation by ensuring these dependencies are installed on your CentOS 7|CentOS 8 server. So follow steps in the next sections to ensure all is set.

Before any installation we recommend you perform an update on the OS layer:

sudo yum -y update

A reboot is also essential once the upgrade is made:

sudo reboot -f

Step 1: Install MariaDB Database Server

We have a comprehensive guide on installation of MariaDB on CentOS 7|CentOS 8. Run the commands below to install the latest stable release of MariaDB database server.

curl -LsS -O https://downloads.mariadb.com/MariaDB/mariadb_repo_setup
sudo bash mariadb_repo_setup
sudo yum install MariaDB-server MariaDB-client MariaDB-backup

Start and enable mariadb database service:

sudo systemctl enable --now mariadb

Secure database server after installation:

$ sudo mariadb-secure-installation
Switch to unix_socket authentication [Y/n] n
Change the root password? [Y/n] y
Remove anonymous users? [Y/n] y
Disallow root login remotely? [Y/n] y
Remove test database and access to it? [Y/n] y
Reload privilege tables now? [Y/n] y

Step 2: Install git 2.x on CentOS 7|CentOS 8

Install git 2.x on your CentOS 7 server using our guide below.

Install latest version of Git ( Git 2.x ) on CentOS 7

Confirm git version.

$ git --version
git version 2.34.1

Step 3: Install Ansible on CentOS 7|CentOS 8

Install Ansible on your CentOS 7 server.

sudo yum -y install epel-release
sudo yum -y install ansible

Test if ansible command is available.

$ ansible --version
ansible 2.9.27
  config file = /etc/ansible/ansible.cfg
  configured module search path = [u'/root/.ansible/plugins/modules', u'/usr/share/ansible/plugins/modules']
  ansible python module location = /usr/lib/python2.7/site-packages/ansible
  executable location = /usr/bin/ansible
  python version = 2.7.5 (default, Nov 16 2020, 22:23:17) [GCC 4.8.5 20150623 (Red Hat 4.8.5-44)]

Step 4: Download Semaphore

Visit the Semaphore Releases page and copy the download link for your OS.

sudo yum -y install wget curl
VER=$(curl -s https://api.github.com/repos/ansible-semaphore/semaphore/releases/latest|grep tag_name | cut -d '"' -f 4|sed 's/v//g')
wget https://github.com/ansible-semaphore/semaphore/releases/download/v$VER/semaphore_$VER_linux_amd64.rpm

Install Semaphore package:

$ sudo rpm -Uvh semaphore_$VER_linux_amd64.rpm
 Preparing…                          ################################# [100%]
 Updating / installing…
    1:semaphore-0:2.8.53-1                ################################# [100%]

Check if you have semaphore binary in your $PATH.

$ which semaphore
/usr/bin/semaphore

$ semaphore  version
v2.8.53

Usage help document:

$ semaphore  --help
Ansible Semaphore is a beautiful web UI for Ansible.
Source code is available at https://github.com/ansible-semaphore/semaphore.
Complete documentation is available at https://ansible-semaphore.com.

Usage:
  semaphore [flags]
  semaphore [command]

Available Commands:
  completion  generate the autocompletion script for the specified shell
  help        Help about any command
  migrate     Execute migrations
  server      Run in server mode
  setup       Perform interactive setup
  upgrade     Upgrade to latest stable version
  user        Manage users
  version     Print the version of Semaphore

Flags:
      --config string   Configuration file path
  -h, --help            help for semaphore

Use "semaphore [command] --help" for more information about a command.

Step 5: Setup Semaphore

Run the following command to start Semaphore setup in your system.

$ sudo semaphore setup
Hello! You will now be guided through a setup to:

1. Set up configuration for a MySQL/MariaDB database
2. Set up a path for your playbooks (auto-created)
3. Run database Migrations
4. Set up initial semaphore user & password

What database to use:
   1 - MySQL
   2 - BoltDB
   3 - PostgreSQL
 (default 1): 1
   DB Hostname (default 127.0.0.1:3306): 
   DB User (default root): root
   DB Password:   
   DB Name (default semaphore): semaphore
   Playbook path (default /tmp/semaphore): /opt/semaphore
   Web root URL (optional, example http://localhost:8010/):  http://localhost:8010/
   Enable email alerts (y/n, default n): n
   Enable telegram alerts (y/n, default n): n
   Enable LDAP authentication (y/n, default n): n

Confirm these values are correct to initiate setup.

 Is this correct? (yes/no): yes
 Config output directory (default /root): 
 WARN[0037] An input error occured:unexpected newline    
 Running: mkdir -p /root..
 Configuration written to /root/config.json..
 Pinging db.. 
 Running DB Migrations..
 Checking DB migrations
 Creating migrations table
......
Migrations Finished

Set username

Username: admin
Email: [email protected]
WARN[0268] sql: no rows in result set                    level=Warn
 Your name: Admin User
 Password: StrongUserPassword 
 You are all setup Admin User!
 Re-launch this program pointing to the configuration file
 ./semaphore -config /root/config.json

To run as daemon:
 nohup ./semaphore -config /root/config.json &
You can login with [email protected] or computingpost.

You can set other configuration values on the file /root/config.json.

Step 6: Configure systemd unit for Semaphore

Let’s now configure Semaphore Ansible UI to be managed by systemd.

Create systemd service unit file.

sudo vi /etc/systemd/system/semaphore.service

The add:

[Unit]
Description=Semaphore Ansible UI
Documentation=https://github.com/ansible-semaphore/semaphore
Wants=network-online.target
After=network-online.target

[Service]
Type=simple
ExecReload=/bin/kill -HUP $MAINPID
ExecStart=/usr/bin/semaphore server --config /etc/semaphore/config.json
SyslogIdentifier=semaphore
Restart=always

[Install]
WantedBy=multi-user.target

Create Semaphore configurations directory:

sudo mkdir /etc/semaphore

Copy your configuration file to created directory:

sudo ln -s /root/config.json /etc/semaphore/config.json

Stop running instances of Semaphore.

sudo pkill semaphore

Confirm:

ps aux | grep semaphore

Reload systemd and start semaphore service.

sudo systemctl daemon-reload
sudo systemctl restart semaphore

Check status to see if running:

$ systemctl status semaphore
● semaphore.service - Semaphore Ansible UI
   Loaded: loaded (/etc/systemd/system/semaphore.service; disabled; vendor preset: disabled)
   Active: active (running) since Tue 2022-04-19 13:29:42 UTC; 3s ago
     Docs: https://github.com/ansible-semaphore/semaphore
 Main PID: 8636 (semaphore)
   CGroup: /system.slice/semaphore.service
           └─8636 /usr/bin/semaphore server --config /etc/semaphore/config.json

Apr 19 13:29:42 centos.example.com systemd[1]: Started Semaphore Ansible UI.
Apr 19 13:29:42 centos.example.com semaphore[8636]: MySQL [email protected]:3306 semaphore
Apr 19 13:29:42 centos.example.com semaphore[8636]: Tmp Path (projects home) /tmp/semaphore
Apr 19 13:29:42 centos.example.com semaphore[8636]: Semaphore v2.8.53
Apr 19 13:29:42 centos.example.com semaphore[8636]: Interface
Apr 19 13:29:42 centos.example.com semaphore[8636]: Port :3000
Apr 19 13:29:42 centos.example.com semaphore[8636]: Server is running

Set Service to start at boot.

$ sudo systemctl enable semaphore
Created symlink /etc/systemd/system/multi-user.target.wants/semaphore.service → /etc/systemd/system/semaphore.service.

Port 3000 should now be Open

$ sudo ss -tunelp | grep 3000
tcp    LISTEN     0      128    [::]:3000               [::]:*                   users:(("semaphore",pid=8636,fd=8)) ino:36321 sk:ffff8ae3b4e59080 v6only:0 <->