MongoDB cli 中的 try catch

這是在調整團隊 MongoDB instance 時遇到的問題：某一隻 js 會在 db init 時執行 create user 的動作，完成後會繼續建立其他 collection 跟 index，但因為這個 user 是跨 db 的 user ，已經被其他 db init 建立過了，所以打算透過 try catch 來處理：create user 失敗就改用 grant 的方式來讓 user 有權限

基本環境說明

macOS Monterey 12.1
docker desktop 4.3.2 (72729)
docker images
- mongo:4.4.11

建立測試環境

init/0.js

use admin;
db.createUser(
    {
        user: "backupuser",
        pwd: "pass.123",
        roles: [ { role: "readWrite", db: "demo" } ]
    }
);

init/1.js

use admin;
db.createUser(
    {
        user: "backupuser",
        pwd: "pass.123",
        roles: [ { role: "readWrite", db: "test" } ]
    }
);

mongo-init.sh

#! /bin/bash
init_mongodb(){
        
    for file in /tmp/mongo/*.js; do
        echo $file
        mongo -u $MONGO_INITDB_ROOT_USERNAME -p $MONGO_INITDB_ROOT_PASSWORD < $file
    done
}
        
main(){
    echo "init_data"
    init_mongodb
}
        
main "$@"

docker-compose

version: '3.1'
services:
  mongo:
    image: mongo:4.4.11
    restart: always
    environment:
      MONGO_INITDB_ROOT_USERNAME: root
      MONGO_INITDB_ROOT_PASSWORD: pass.123
    volumes:
      - ${PWD}/init:/tmp/mongo
      - ${PWD}/mongo-init.sh:/docker-entrypoint-initdb.d/mongo-init.sh

錯誤訊息

訊息內容

mongo_1  | uncaught exception: Error: couldn't add user: User "backupuser@admin" already exists :
mongo_1  | _getErrorWithCode@src/mongo/shell/utils.js:25:13
mongo_1  | DB.prototype.createUser@src/mongo/shell/db.js:1386:11
mongo_1  | @(shell):1:1
mongo_1  | bye

錯誤截圖

解決方式：在 mongo shell 中使用 try catch

調整啟動方式

1-1. init/0.js

db = db.getSiblingDB("admin")
try {
    db.createUser(
        {
            user: "backupuser",
            pwd: "pass.123",
            roles: [ { role: "readWrite", db: "demo" } ]
        }
    );
}
catch (err) {
    print ("backupuser user already created");
    db.grantRolesToUser( "backupuser", [ { role: "readWrite", db: "demo" }] );
}

1-2. init/1.js

db = db.getSiblingDB("admin")
try {
    db.createUser(
        {
            user: "backupuser",
            pwd: "pass.123",
            roles: [ { role: "readWrite", db: "test" } ]
        }
    );
}
catch (err) {
    print ("backupuser user already created");
    db.grantRolesToUser( "backupuser", [ { role: "readWrite", db: "test" }] );
}

1-3. docker-compose

version: '3.1'
services:
  mongo:
    image: mongo:4.4.11
    restart: always
    environment:
      MONGO_INITDB_ROOT_USERNAME: root
      MONGO_INITDB_ROOT_PASSWORD: pass.123
    volumes:
      - ${PWD}/init:/docker-entrypoint-initdb.d/

調整 js 寫法

2-1. init/0.js

use admin;
initFunction= {
    start: function(){
        try {
            db.createUser(
                {
                    user: "backupuser",
                    pwd: "pass.123",
                    roles: [ { role: "readWrite", db: "demo" } ]
                }
            );
        }
        catch (err) {
            print(err);
            db.grantRolesToUser( "backupuser", [ { role: "readWrite", db: "demo" }] );
        }
    }
}
        
initFunction.start();

2-2. init/1.js

use admin;
initFunction= {
    start: function(){
        try {
            db.createUser(
                {
                    user: "backupuser",
                    pwd: "pass.123",
                    roles: [ { role: "readWrite", db: "test" } ]
                }
            );
        }
        catch (err) {
            print(err);
            db.grantRolesToUser( "backupuser", [ { role: "readWrite", db: "test" }] );
        }
    }
}
        
initFunction.start();

心得

如果是 for docker image 的 init 使用 mongodb image 預設的 MONGO_INITDB_DATABASE 機制：調整啟動方式 會單純許多

但如果想要讓 container 與實體 mongodb instance 行為一致，就可以參考使用 調整 js 寫法

修改前
修改後

文章目錄

MongoDB cli 中的 try catch

基本環境說明

錯誤訊息

解決方式：在 mongo shell 中使用 try catch

心得

參考資訊