如何用jq的ascii_downcase转换docker-compose环境变量键名

需求与问题 #

需要将Docker Compose配置中的环境变量键名全部转换为小写，并把下划线替换为连字符，同时保留变量值的原始大小写。已成功实现服务键名的转换，但对环境变量的转换尝试未生效。

原始配置片段（JSON格式） #

{
  "name": "qualimarc-docker-prod",
  "services": {
    "qualimarc-watchtower": {
      "cpus": 0.5,
      "command": null,
      "container_name": "qualimarc-watchtower",
      "entrypoint": null,
      "environment": {
        "WATCHTOWER_CLEANUP": "true",
        "WATCHTOWER_DEBUG": "false",
        "WATCHTOWER_NOTIFICATIONS": "slack",
        "WATCHTOWER_NOTIFICATION_SLACK_CHANNEL": "#notif-qualimarc",
        "WATCHTOWER_NOTIFICATION_SLACK_HOOK_URL": "https://hooks.slack.com/services/TCRRETSQ4/B03QN4MTU3B/",
        "WATCHTOWER_NOTIFICATION_SLACK_IDENTIFIER": "diplotaxis1-prod qualimarc-watchtower",
        "WATCHTOWER_NO_STARTUP_MESSAGE": "true",
        "WATCHTOWER_POLL_INTERVAL": "60",
        "WATCHTOWER_RUN_ONCE": "false",
        "WATCHTOWER_SCOPE": "qualimarc-watchtower-scope",
        "WATCHTOWER_WARN_ON_HEAD_FAILURE": "never"
      },
      "image": "containrrr/watchtower:1.4.0",
      "labels": {
        "com.centurylinklabs.watchtower.scope": "qualimarc-watchtower-scope"
      },
      "mem_limit": "3221225472",
      "memswap_limit": "3221225472",
      "networks": {
        "default": null
      },
      "restart": "unless-stopped",
      "volumes": [
        {
          "type": "bind",
          "source": "/var/run/docker.sock",
          "target": "/var/run/docker.sock",
          "bind": {
            "create_host_path": true
          }
        }
      ]
    }
  }
}

已实现的服务键名转换命令 #

echo $(docker-compose config --format json) | jq '.services|with_entries(.key|=ascii_downcase)'

之前尝试的无效命令 #

echo $(docker-compose config --format json) | jq '.services|with_entries(.value|with_entries(.key|=ascii_upcase))'

解决方案 #

使用以下jq命令可完成环境变量键名的转换，同时保留值的原始大小写：

echo $(docker-compose config --format json) | jq '.services |= with_entries(.value.environment |= with_entries(.key |= (ascii_downcase | gsub("_"; "-"))))'

命令解释 #

• .services |= with_entries(...)：遍历所有服务，对每个服务的配置进行修改
• .value.environment |= with_entries(...)：针对服务下的environment字段，遍历其键值对
• .key |= (ascii_downcase | gsub("_"; "-"))：将键名先转为小写，再把下划线替换为连字符

转换后的environment片段效果 #

"environment": {
  "watchtower-cleanup": "true",
  "watchtower-debug": "false",
  "watchtower-notifications": "slack",
  "watchtower-notification-slack-channel": "#notif-qualimarc",
  "watchtower-notification-slack-hook-url": "https://hooks.slack.com/services/TCRRETSQ4/B03QN4MTU3B/",
  "watchtower-notification-slack-identifier": "diplotaxis1-prod qualimarc-watchtower",
  "watchtower-no-startup-message": "true",
  "watchtower-poll-interval": "60",
  "watchtower-run-once": "false",
  "watchtower-scope": "qualimarc-watchtower-scope",
  "watchtower-warn-on-head-failure": "never"
}

同时转换服务键名和环境变量键名 #

如果需要一次性完成服务键名小写转换+环境变量键名格式转换，可使用合并命令：

echo $(docker-compose config --format json) | jq '.services |= with_entries(.key |= ascii_downcase | .value.environment |= with_entries(.key |= (ascii_downcase | gsub("_"; "-"))))'

内容的提问来源于stack exchange，提问作者Nathanaël Blanchet