From https://wiki.imciel.com/sandry/%E5%91%BD%E4%BB%A4%E8%A1%8C%E6%8F%90%E4%BA%A4gitlab_merge_request

gitlab_create_merge_request.sh

#!/bin/bash

usage() 
{
  echo "usage: 使用命令行提交 Merge Request，参数如下：
  -p 源工程 ID
  -s 源工程分支
  -d 目标工程 ID
  -t 目标工程分支
  -u 用户 ID
  -m Merge Request 标题
  相关 ID 请使用 gitlab 命令查找" 1>&2; 
  exit 1;
}

if command -v gitlab >/dev/null 2>&1; then 
  echo "exists gitlab" > /dev/null 2>&1
else
  echo 'gitlab 不存在，请安装，https://github.com/NARKOZ/gitlab' 
fi

export GITLAB_API_ENDPOINT="http://gitlab.example.com/api/v3"


if [ "${GITLAB_API_PRIVATE_TOKEN}x" == "x" ];then
  echo "请设置 Gitlab private token，若无 private token，请到 http://gitlab.example.com/profile/personal_access_tokens 生成"
fi

# 默认目标工程 ID
des_project="222"
# 默认源工程 ID
source_project="233"
# 默认目标分支
des_branch="develop"
# 默认目标分支
source_branch="develop"
# 默认提交用户
current_user="68"

while getopts ":s:t:p:m:u:d:" o
do
  case "${o}" in
    d)
      des_project=${OPTARG}
      ;;
    p)
      source_project=${OPTARG}
      ;;
    s)
      source_branch=${OPTARG}
      ;;
    t)
      des_branch=${OPTARG}
      ;;
    u)
      current_user=${OPTARG}
      ;;
    m)
      message=${OPTARG}
      ;;
    *)
      usage
      ;; 
  esac
done

# 标题必填
if [ "${message}x" == "x" ];then
  echo "请填写 Merge request 标题"
  exit 1;
fi

# 得到 gitlab 命令行的输出
output=$(gitlab create_merge_request ${source_project} "${message}" "{ source_branch: '${source_branch}', target_branch: '${des_branch}', assignee_id: ${current_user}, target_project_id: ${des_project}}" --json)

# 如查包含 created_at 字符串，则表示提交成功，失败时输出日志
success=$(echo ${output} | grep "created_at")
if [ "${success}x" == "x" ];then
  echo ${output}
else
  echo "提交成功"
fi