allard
180 lines
6.1 KiB
Markdown
180 lines
6.1 KiB
Markdown
MongoDB Sharded Cluster — Initialization Guide
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Raspberry Pi 3-node MicroK8s cluster, MongoDB 8.0 Community
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Architecture
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┌─────────────────────────────────────────────────────┐
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│ mongos (x2) │
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│ mongo-mongos.mongodb.svc.cluster.local │
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└───────────────────┬─────────────────────────────────┘
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│
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┌───────────┴───────────┐
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│ │
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┌───────▼────────┐ ┌─────────▼──────┐ ┌──────────────────┐
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│ Config Server │ │ Shard 0 │ │ Shard 1 │
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│ ReplicaSet │ │ ReplicaSet │ │ ReplicaSet │
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│ (3 replicas) │ │ (3 replicas) │ │ (3 replicas) │
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│ port 27019 │ │ port 27018 │ │ port 27018 │
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└────────────────┘ └────────────────┘ └──────────────────┘
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Step 0 — Prerequisites
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======
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On pisvrwsv07 create the data directories:
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sudo mkdir -p /mnt/mongodb/configsvr0 /mnt/mongodb/configsvr2 /mnt/mongodb/shard0-0 /mnt/mongodb/shard1-0
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sudo chown -R 999:999 /mnt/mongodb
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On pisvrwsv08 create the data directories:
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sudo mkdir -p /mnt/mongodb/configsvr1 /mnt/mongodb/shard0-1 /mnt/mongodb/shard1-1
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sudo chown -R 999:999 /mnt/mongodb
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step 1
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======
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kubectl apply -f namespace.yaml
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Step 2
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======
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Generate the keyfile and create the secret:
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openssl rand -base64 756 > mongo-keyfile
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chmod 400 mongo-keyfile
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kubectl create secret generic mongo-keyfile –from-file=keyfile=./mongo-keyfile -n mongodb
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You can delete the local file after this, it’s stored in the secret.
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rm mongo-keyfile
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Step 3
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======
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Apply manifest:
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kubectl apply -f mongodb.yaml
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Wait for all pods to be Running before continuing:
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kubectl get pods -n mongodb -w
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All 9 pods (3 configsvr + 3 shard0 + 3 shard1) must be Running.
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Step 4
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======
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Initialize the Config Server replica set
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kubectl exec -n mongodb mongo-configsvr-0 -- mongosh --port 27019 --eval '
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rs.initiate({
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_id: "configReplSet",
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configsvr: true,
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members: [
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{ _id: 0, host: "mongo-configsvr-0.mongo-configsvr.mongodb.svc.cluster.local:27019" },
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{ _id: 1, host: "mongo-configsvr-1.mongo-configsvr.mongodb.svc.cluster.local:27019" },
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{ _id: 2, host: "mongo-configsvr-2.mongo-configsvr.mongodb.svc.cluster.local:27019" }
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]
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})'
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Step 5
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======
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initialize shard0:
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kubectl exec -n mongodb mongo-shard0-0 -- mongosh --port 27018 --eval '
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rs.initiate({
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_id: "shard0ReplSet",
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members: [
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{ _id: 0, host: "mongo-shard0-0.mongo-shard0.mongodb.svc.cluster.local:27018" },
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{ _id: 1, host: "mongo-shard0-1.mongo-shard0.mongodb.svc.cluster.local:27018" },
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{ _id: 2, host: "mongo-shard0-arbiter-0.mongo-shard0-arbiter.mongodb.svc.cluster.local:27018", arbiterOnly: true }
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]
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})'
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Step 6
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======
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initialize shard1:
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kubectl exec -n mongodb mongo-shard1-0 -- mongosh --port 27018 --eval '
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rs.initiate({
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_id: "shard1ReplSet",
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members: [
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{ _id: 0, host: "mongo-shard1-0.mongo-shard1.mongodb.svc.cluster.local:27018" },
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{ _id: 1, host: "mongo-shard1-1.mongo-shard1.mongodb.svc.cluster.local:27018" },
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{ _id: 2, host: "mongo-shard1-arbiter-0.mongo-shard1-arbiter.mongodb.svc.cluster.local:27018", arbiterOnly: true }
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]
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})'
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Step 7
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======
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Create admin user:
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kubectl exec -n mongodb \
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$(kubectl get pod -n mongodb -l app=mongo-mongos -o jsonpath='{.items[0].metadata.name}') -- \
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mongosh --eval '
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db.getSiblingDB("admin").createUser({
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user: "admin",
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pwd: "changeme",
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roles: [{ role: "root", db: "admin" }]
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})'
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check statusses:
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Status configsvr:
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kubectl exec -n mongodb mongo-configsvr-0 -- mongosh --port 27019 -u admin -p changeme --authenticationDatabase admin --eval 'rs.status().members.forEach(m => print(m.name, m.stateStr))'
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Status shards without auth:
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kubectl exec -n mongodb mongo-shard0-0 -- mongosh --port 27018 --eval 'rs.status().members.forEach(m => print(m.name, m.stateStr))'
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status shards with auth:
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kubectl exec -n mongodb mongo-shard0-0 -- mongosh --port 27018 -u admin -p changeme --authenticationDatabase admin --eval 'rs.status().members.forEach(m => print(m.name, m.stateStr))'
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step 8
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======
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MongoDB 5+ requires explicit default write concern when arbiters are involved. Fix it by setting the cluster-wide write concern first:
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kubectl exec -n mongodb \
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$(kubectl get pod -n mongodb -l app=mongo-mongos -o jsonpath='{.items[0].metadata.name}') -- \
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mongosh -u admin -p Mongodb01@ --authenticationDatabase admin --eval '
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db.adminCommand({
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setDefaultRWConcern: 1,
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defaultWriteConcern: { w: 1 },
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defaultReadConcern: { level: "local" }
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})'
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step 9
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======
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Add shards
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kubectl exec -n mongodb \
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$(kubectl get pod -n mongodb -l app=mongo-mongos -o jsonpath='{.items[0].metadata.name}') -- \
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mongosh -u admin -p changeme --authenticationDatabase admin --eval '
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sh.addShard("shard0ReplSet/mongo-shard0-0.mongo-shard0.mongodb.svc.cluster.local:27018,mongo-shard0-1.mongo-shard0.mongodb.svc.cluster.local:27018")
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sh.addShard("shard1ReplSet/mongo-shard1-0.mongo-shard1.mongodb.svc.cluster.local:27018,mongo-shard1-1.mongo-shard1.mongodb.svc.cluster.local:27018")
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sh.status()'
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step 10
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-------
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connection string for applications:
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mongodb://admin:Mongodb01@mongo-mongos.mongodb.svc.cluster.local:27017/mydb?authSource=admin
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mongoose:
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mongoose.connect('mongodb://admin:Mongodb01@mongo-mongos.mongodb.svc.cluster.local:27017/mydb?authSource=admin')
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step 11
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=======
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If you want to enable sharding on a specific database and collection:
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kubectl exec -n mongodb \
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$(kubectl get pod -n mongodb -l app=mongo-mongos -o jsonpath='{.items[0].metadata.name}') -- \
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mongosh -u admin -p Mongodb01@ --authenticationDatabase admin --eval '
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sh.enableSharding("mydb")
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sh.shardCollection("mydb.mycollection", { _id: "hashed" })'
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