MongoDB + Liquibase = mongol

Liquibase-like tool for MongoDB. Manipulating structure and data of MongoDB in migration-based way.

##How-to

Structure:

• Mongol expects that migrate and rollback commands will be provided with a file (default ./changelog.json) in JSON format:

Main changelog file format:

{
	"connection":"mongodb://username:password@mymongodb:27017/myauthdb",
	"dbname":"mydbname",
	"migrations": [
		{
			"include": "some-folder/changelog.json",
			"relativeToChangelogFile": true
		}
	]
}

• connection - Required. Full connection string to your MongoDB database
• dbname - Required. Database name inside MongoDB to which migrations will be applied
• migrations - Required. List of migrations to apply. Several formats are acceptible (see below)
• include - Required. Path to migration changelog file. Full or relative to this changelog file, according to relativeToChangelogFile
• relativeToChangelogFile - Optional. Indicates whether include path should be treated as relative to this changelog file. Default: true

Following formats are acceptable:

• Migrations is of type string. relativeToChangelogFile is true, by default.

{
	"connection":"mongodb://username:password@mymongodb:27017/myauthdb",
	"dbname":"mydbname",
	"migrations": "some-folder/changelog.json"
}

• Migrations is of type array of strings. relativeToChangelogFile is true, by default.

{
	"connection":"mongodb://username:password@mymongodb:27017/myauthdb",
	"dbname":"mydbname",
	"migrations": ["some-folder/changelog.json", "another-folder/changelog.json"]
}

• Full format, ommiting relativeToChangelogFile.

{
	"connection":"mongodb://username:password@mymongodb:27017/myauthdb",
	"dbname":"mydbname",
	"migrations": [
		{
			"include": "some-folder/changelog.json"
		}
	]
}

• Full format.

{
	"connection":"mongodb://username:password@mymongodb:27017/myauthdb",
	"dbname":"mydbname",
	"migrations": [
		{
			"include": "some-folder/changelog.json",
			"relativeToChangelogFile": true
		}
	]
}

Migration changelog file format:

{
  "id": "migration_id",
  "changes": [
    {
      "migration": {
        "include": "00001_first_migration.json",
        "relativeToChangelogFile": true
      },
      "rollback": {
        "include": "00001_first_migration_rollback.json",
        "relativeToChangelogFile": true
      }
    }
  ]
}

• id - required. Migration's ID.
• changes - required. List of changes to apply. Contains an object with 2 fields migration - forward migration, that is applied by migrate command; rollback - backward migration, that is applied by rollback command.
• migration - required. Lists direct commands to apply during forward migration. Has the same format as migrations tag from main changelog file (see above).
• rollback - optional. Lists direct commands to apply during backward migration. Has the same format as migration tag.

Following formats are acceptable:

{
  "id": "20190101_00001_initial_migration",
  "changes": [
    {
      "migration": {
        "include": "00001_first_migration.json",
        "relativeToChangelogFile": true
      }
    }
  ]
}

{
  "id": "20190101_00001_initial_migration",
  "changes": [
    {
      "migration": {
        "include": "00001_first_migration.json",
      }
    }
  ]
}

{
  "id": "20190101_00001_initial_migration",
  "changes": [
    {
      "migration": "00001_first_migration.json"
    }
  ]
}

{
  "id": "20190101_00001_initial_migration",
  "changes": [
    {
      "migration": ["00001_first_migration.json", "00002_second_migration.json"]
    }
  ]
}

Migration file format:

• migrations must be in a valid extended-json format: https://github.com/mongodb/specifications/blob/master/source/extended-json.rst

• migrations support MongoDB database commands: https://docs.mongodb.com/manual/reference/command/

• pay attention, that different versions of MongoDB support different sets of commands.

• migrations support sets of commands, just follow this syntax:

{
  "cmds" [
    {
      //first command in extended json format
    },
    {
      //second command in extended json format
    }
    ...
  ]
}

Example (single command). Following migration creates collection collection_name with validator:

{
  "create": "collection_name",
  "validator":{
    "$jsonSchema":{
      "bsonType":"object",
      "required":["name"],
      "properties":{
        "name":{
          "bsonType":"string",
          "description":"must be a string and is required"
        }
      }
    }
  }
}

Example (several commands). Following migration creates collection collection_name with validator and fills it up with test value:

{
  "cmds" [
    {
      "create": "collection_name",
      "validator":{
        "$jsonSchema":{
          "bsonType":"object",
          "required":["name"],
          "properties":{
            "name":{
              "bsonType":"string",
              "description":"must be a string and is required"
            }
          }
        }
      }
    },
    {
      "insert": "collection_name",
      "documents":[
        {
          "name": "Test value",
          "bsonType":"object",
          "required":["name"],
          "properties":{
            "name":{
              "bsonType":"string",
              "description":"must be a string and is required"
            }
          }
        }
      ]
    }
  ]
}

Example

Can be found here

Run

Docker-way:

• forward migrations

docker run --rm -v /path/to/src:/mongol/src coldze/mongol:latest mongol migrate --path=/mongol/src/changelog.json 

• backward migrations

docker run --rm -v /path/to/src:/mongol/src coldze/mongol:latest mongol rollback --path=/mongol/src/changelog.json 

Compile from source code & run:

1. Install go: https://golang.org/doc/install
2. Don't forget to add $GOBIN to your $PATH
3. Run the following:

go get -u github.com/kardianos/govendor //govendor tool to handle dependecies, see vendor/vendor.json
go get github.com/coldze/mongol
cd $GOPATH/src/github.com/coldze/mongol
govendor sync
go install
mongol --help

Docker-hub:

https://hub.docker.com/r/coldze/mongol/

Functionality

• forward migrations:

mongol migrate --path=/path/to/changelog.json --count=123

• backward migrations/rollbacks. You must specify amount of migrations to rollback. Count takes into consideration ALL migrations, specified in changelog.json, whether they were applied or not. So if you have 10 migrations in total, but only 5 were applied and you want to rollback last 2, you will have to specify count=7 (last 5 missing, 2 to rollback):

mongol rollback --path=/path/to/changelog.json --count=7

• MongoDB supports JavaScript starting from 3.0 up to 3.6, in 4.0 it was deprecated, so you're able to use eval in migrations for MongoDB 3.x versions.

Sample

Folder structure

./changelog.json //contains information about connection to mongo, includes sub-changelogs
./migrations/20190101/changelog.json //sub-changelog with migrations created at 2019-01-01
./migrations/20190101/0001_fill_data.json
./migrations/20190101/0001_fill_data_rollback.json

Migration file

Changelog file

Root changelog file

Running a test

Change mongo-db settings in $GOPATH/src/github.com/coldze/mongol/test/changelog.json and execute:

mongol migrate --path=$GOPATH/src/github.com/coldze/mongol/test/changelog.json