tomodo 0.1.0rc5

A CLI tool to control MongoDB deployments on Docker

tomodo

tomodo is a Toolbox for MongoDB on Docker.

Use it upgrade existing standalone MongoDB deployments or MongoDB Replica Sets deployed with Docker.

Installation

You can install the tool using the tomodo PyPi package with pip:

pip install tomodo

How Upgrades Work

Upgrading MongoDB is officially supported through specific upgrade paths. For example, in order to upgrade a MongoDB database from version 3.6 to version 6.0, one cannot do it in a one-off upgrade. Instead, there's a specific, well-documented upgrade path for each upgrade. For example:

• Upgrading to version 4.0 can only be done from version 3.6 or later (see docs)
• Upgrading to version 4.2 can only be done from version 4.0 or later (see docs)
• Upgrading to version 4.4 can only be done from version 4.2 or later (see docs)
• etc.

For this reason, if the process of upgrading from your current MongoDB version to a target version requires five hops (e.g., 3.6.x to 6.0.x), tomodo will perform five upgrades, one after the other.

Usage

MongoDB Version Upgrade

Below is a simplified example of a tomodo command you can run in order to upgrade a locally-deployed MongoDB Replica Set to version 4.4:

tomodo \
  --no-standalone \
  --target-version 5.0 \
  --hostname "mongodb://mongodb-rs-1:27011/?replicaSet=mongodbrs"

Set Up a Test Environment

In order to test the tool locally, you can create a local MongoDB Replica Set and upgrade it.

1. First, create a Docker network for your test deployment:

   docker network create mongodbnet > /dev/null 2>&1 || echo "Network already exists"
   

2. Next, deploy a MongoDB Replica Set with N members (3 members in the example below):

   members=3
   mongodb_ver=3.6.18
   for ((i=1; i<=members; i++)); do
     rm -rf ./data/db${i}/* || echo 'Nothing to clean up'
     mkdir -p ./data/db${i}
     docker run -d \
       -v $(pwd)/data/db${i}:/data/db${i} \
       -h mongodb-rs-${i} \
       --network-alias mongodb-rs-${i} \
       --name mongodb-rs-${i} \
       -u 1000:1000 \
       -p "2701${i}:2701${i}" \
       --network mongodbnet \
       mongo:${mongodb_ver} \
       --dbpath /data/db${i} \
       --replSet mongodbrs \
       --bind_ip_all \
       --logpath /data/db${i}/mongod.log \
       --port 2701${i}
   done
   

3. Initialize a MongoDB Replica Set (replace the value of members if you chose a member count that's different from 3:

   members=3
   hosts="127.0.0.1   mongodb-rs-1"
   init_script="rs.initiate()"
   for ((i=2; i<=members; i++)); do
     init_script="${init_script}; rs.add('mongodb-rs-${i}:2701${i}')"
     hosts="${hosts},mongodb-rs-${i}"
   done
   mongosh \
     --quiet "mongodb://mongodb-rs-1:27011" \
     --eval "${init_script}"
   

4. Optional, but recommended: add the host mapping to the containers:

   hosts="127.0.0.1   mongodb-rs-1"
   for ((i=2; i<=members; i++)); do
      hosts="${hosts},mongodb-rs-${i}"
    done
   echo $hosts | sudo tee -a /etc/hosts
   

5. Verify the deployment was successful by running the following docker command:

   docker ps
   

   The output should be along the following lines:

   CONTAINER ID   IMAGE          COMMAND                  CREATED              STATUS              PORTS                                 NAMES
   36ddd65fe63a   mongo:3.6.18   "docker-entrypoint.s…"   About a minute ago   Up About a minute   0.0.0.0:27013->27013/tcp, 27017/tcp   mongodb-rs-3
   0e9d3b357be9   mongo:3.6.18   "docker-entrypoint.s…"   About a minute ago   Up About a minute   0.0.0.0:27012->27012/tcp, 27017/tcp   mongodb-rs-2
   d7f43e5b0003   mongo:3.6.18   "docker-entrypoint.s…"   About a minute ago   Up About a minute   0.0.0.0:27011->27011/tcp, 27017/tcp   mongodb-rs-1
   

6. Now that the Replica Set is initialized, you can connect to it using mongosh:

   mongosh \
   "mongodb://mongodb-rs-1:27011,mongodb-rs-2:27012,mongodb-rs-3:27013/?replicaSet=mongodbrs"
   

Outstanding Tasks:

• Support rollbacks on failure
• Support downgrades
• Support Replica Set upgrades with multiple remote docker hosts
• Customizable container selection (e.g., by name/ID)
• Support configuration file