シェルスクリプトとAnsibleの冪等性作りこみの例

プロセスの起動の冪等性

例: nginxのプロセス起動の冪等性

code:shell

PROCESS_NAME="nginx"

SERVICE_NAME="nginx"

# プロセスの存在確認

if ps aux | grep -v grep | grep "$PROCESS_NAME" > /dev/null

then

echo "$PROCESS_NAME is already running."

else

echo "$PROCESS_NAME is not running. Starting $SERVICE_NAME."

systemctl start "$SERVICE_NAME"

echo "$SERVICE_NAME started."

fi

code:yaml

---

- name: Ensure nginx is running

hosts: localhost

become: true

tasks:

- name: Check if nginx is running

ansible.builtin.service:

name: nginx

state: started

ユーザーの作成

例:

code:shell

FILE_PATH="/path/to/file.txt"

# ファイルが存在しない場合のみ作成する

touch "$FILE_PATH"

echo "File created."

else

echo "File already exists."

fi

code:yaml

---

- name: Ensure the file exists

hosts: localhost

tasks:

- name: Create file if it doesn't exist

ansible.builtin.file:

path: /path/to/file.txt

state: touch

パッケージのインストール

code:shell

PACKAGE_NAME="git"

# パッケージがインストールされているかを確認し、未インストールならインストール

if dpkg -l | grep -q "$PACKAGE_NAME"; then

echo "$PACKAGE_NAME is already installed."

else

sudo apt-get install -y "$PACKAGE_NAME"

echo "$PACKAGE_NAME installed."

fi

code:yaml

---

- name: Ensure the package is installed

hosts: localhost

become: true

tasks:

- name: Install git package if not installed

ansible.builtin.apt:

name: git

state: present

設定ファイルの修正

code:shell

CONFIG_FILE="/etc/sysctl.conf"

SETTING="net.ipv4.ip_forward=1"

# 設定がファイルに存在しない場合のみ追記する

if grep -q "$SETTING" "$CONFIG_FILE"; then

echo "Setting already exists."

else

echo "$SETTING" >> "$CONFIG_FILE"

sysctl -p

echo "Setting applied."

fi

code:yaml

---

- name: Ensure the setting is present in the config file

hosts: localhost

become: true

tasks:

- name: Add setting if not present

ansible.builtin.lineinfile:

path: /etc/sysctl.conf

line: "net.ipv4.ip_forward=1"

- name: Apply sysctl settings

ansible.builtin.command:

cmd: sysctl -p