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The following guide deploys the Minimus Mongo image together with custom certificates generated with OpenSSL to help you get started. Run the code to try it for yourself.

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Components

  • Mongo image: MongoDB container running with requireTLS and client authentication.
  • certgen.sh script: Generates a custom CA, server, and client certificates using OpenSSL.
  • minidebug image: A Minimus dev toolkit that provides a shell, OpenSSL, and other utilities used to generate the certificates.
  • mongosh installed.

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What this guide demonstrates

  • TLS handshake validation
  • Server/client certificate trust
  • Basic auth and MongoDB operations
  • Image compatibility

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Directory Structure

.
├── certgen.sh             # Certificate generation script
├── create-certs.yml       # Compose file to run certgen container
└── docker-compose.yml     # Compose file to run MongoDB

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Deploy Mongo with TLS certificates

1

Save certgen.sh

Save the following script to a file named certgen.sh. The script is used to generate the TLS certificates and store them in a certs folder on the host.
certgen.sh
#!/bin/sh

set -e
cd /certs

echo "[INFO] Generating OpenSSL config..."
cat > openssl.cnf <<EOF
[req]
distinguished_name = req_distinguished_name
prompt = no

[req_distinguished_name]
CN = mongo

[v3_req]
keyUsage = keyEncipherment, dataEncipherment
extendedKeyUsage = serverAuth
subjectAltName = @alt_names

[v3_client]
keyUsage = digitalSignature
extendedKeyUsage = clientAuth
subjectAltName = @alt_names

[v3_ca]
subjectKeyIdentifier = hash
authorityKeyIdentifier = keyid:always,issuer
basicConstraints = critical, CA:true
keyUsage = critical, keyCertSign, cRLSign

[alt_names]
DNS.1 = mongo
DNS.2 = localhost
IP.1 = 127.0.0.1
IP.2 = 192.168.50.0
IP.3 = 192.168.50.2
IP.4 = 192.168.50.3


EOF

echo "[INFO] Creating CA certificate..."
openssl genrsa -out ca-key.pem 2048
openssl req -x509 -new -nodes -key ca-key.pem -sha256 -days 365 \
  -out ca.pem -subj "/CN=MongoDB Test CA" \
  -extensions v3_ca -config openssl.cnf

echo "[INFO] Creating server certificate..."
openssl genrsa -out server-key.pem 2048
openssl req -new -key server-key.pem -out server.csr \
  -config openssl.cnf -extensions v3_req
openssl x509 -req -in server.csr -CA ca.pem -CAkey ca-key.pem -CAcreateserial \
  -out server-cert.pem -days 365 -sha256 \
  -extfile openssl.cnf -extensions v3_req
cat server-cert.pem server-key.pem > server.pem

echo "[INFO] Creating client certificate..."
openssl genrsa -out client-key.pem 2048
openssl req -new -key client-key.pem -out client.csr -subj "/CN=root"
openssl x509 -req -in client.csr -CA ca.pem -CAkey ca-key.pem -CAcreateserial \
  -out client-cert.pem -days 365 -sha256 \
  -extfile openssl.cnf -extensions v3_client
cat client-cert.pem client-key.pem > client.pem
ls -l /certs/
echo "[INFO] Adjusting permissions..."

# Secure private keys
[ -f server-key.pem ] && chmod 600 server-key.pem
[ -f client-key.pem ] && chmod 600 client-key.pem

# Public certs readable
chmod 644 ca.pem server-cert.pem client-cert.pem server.pem client.pem

# Ownership
chown -R 1000:1000 /certs/*.pem || echo "[WARN] chown failed (non-root?)"

# Final check
for f in ca.pem server.pem client.pem; do
  [ -f "/certs/$f" ] || { echo "[ERROR] Missing: $f"; exit 1; }
done

echo "[SUCCESS] Certificates generated for MongoDB."
2

Save create-certs.yml

Save the following YAML file to run with Docker Compose. It uses the Minimus minidebug image to generate the certificates with the certgen.shshell script. Minidebug is a Minimus dev toolkit that provides a shell, OpenSSL, and other utilities.The certificates will be persisted in the certs volume on the host.
create-certs.yml
services:
  certgen:
    image: reg.mini.dev/minidebug:latest
    container_name: mongo_certgen
    volumes:
    - ./certs:/certs
    - ./certgen.sh:/certgen.sh:ro
    entrypoint:
    - /bin/sh
    - /certgen.sh
    network_mode: none
3

Generate certificates

Run the following to generate the certificates:
docker compose -f create-certs.yml up

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TLS certificates

The script certgen.sh generates the following self-signed certificates:
  • CA certificate (ca.pem)
  • Server certificates (server-cert.pem, server-key.pem)
  • Client certificates (client.pem, client-key.pem)
The setup ensures:
  • Proper SANs for mongo and localhost
  • Client certs with clientAuth
  • Server certs with serverAuth
These certificates will be mounted into the Mongo container.
4

Save Docker Compose script

Save the following Docker Compose script to a file nameddocker-compose.yml. This script sets up the Mongo service with a healthcheck, mounts a volume with the certificates, maps port 27017, and connects the container to a custom network.
docker-compose
services:
  mongo:
    image: reg.mini.dev/mongo:latest
    container_name: mongo_tls
    healthcheck:
      test: ["CMD", "mongosh", "--tls", "--tlsCAFile", "/certs/ca.pem", "--tlsCertificateKeyFile", "/certs/server.pem", "--eval", "db.adminCommand('ping')"]
      interval: 5s
      timeout: 3s
      retries: 10
    environment:
      MONGO_INITDB_ROOT_USERNAME: root
      MONGO_INITDB_ROOT_PASSWORD: rootpass
      MONGO_INITDB_DATABASE: testdb
    volumes:
      - ./certs:/certs:ro
      - mongo_data:/data/db
    ports:
      - "27017:27017"
    command: [
      "mongod",
      "--auth",
      "--bind_ip_all",
      "--tlsMode", "requireTLS",
      "--tlsCertificateKeyFile", "/certs/server.pem",
      "--tlsCAFile", "/certs/ca.pem"
    ]

volumes:
  mongo_data:
5

Run Mongo

Start the Mongo container:
docker compose -f docker-compose.yml up
6

Run tests over mongosh

We will use mongosh, the mongo shell, to connect over HTTPS and run tests. For example, here are a few commands you can try out:
  1. Check db health 
    mongosh "mongodb://root@localhost:27017/admin?authMechanism=SCRAM-SHA-256" \
--tls \
--tlsCAFile ./certs/ca.pem \
--tlsCertificateKeyFile ./certs/client.pem \
--eval 'db.adminCommand("ping")' \
--password rootpass
    You should get the response { ok: 1 } .
  2. Create a test database (for example testdb): 
      mongosh "mongodb://root@localhost:27017/admin?authMechanism=SCRAM-SHA-256" \
    --tls \
    --tlsCAFile ./certs/ca.pem \
    --tlsCertificateKeyFile ./certs/client.pem \
    --password rootpass \
    --eval '
  const dbname = "testdb";
  const testdb = db.getSiblingDB(dbname);
  const result = testdb.sample.insertOne({ createdAt: new Date(), msg: "Hello from mongosh over TLS" });
  print("✅ Created database:", dbname);
  printjson(result);
  '
  3. List all databases. 
      mongosh "mongodb://root@localhost:27017/admin?authMechanism=SCRAM-SHA-256" \
    --tls \
    --tlsCAFile ./certs/ca.pem \
    --tlsCertificateKeyFile ./certs/client.pem \
    --password rootpass \
    --eval '
  const res = db.adminCommand({ listDatabases: 1 });
  printjson(res);
  '
  4. Create document in testdb.docs: 
      mongosh "mongodb://root@localhost:27017/admin?authMechanism=SCRAM-SHA-256" \
    --tls \
    --tlsCAFile ./certs/ca.pem \
    --tlsCertificateKeyFile ./certs/client.pem \
    --password rootpass \
    --eval '
  const now = new Date().toISOString();
  const res = db.getSiblingDB("testdb").docs.insertOne({
    test: "Welcome to TLS MongoDB running on a Minimus image",
    timestamp: now
  });
  printjson(res);
  '
  5. Create a user (for example,testuser with readWrite role on testdb), get user details, and delete the user: 
    mongosh "mongodb://root@localhost:27017/admin?authMechanism=SCRAM-SHA-256" \
  --tls \
  --tlsCAFile ./certs/ca.pem \
  --tlsCertificateKeyFile certs/client.pem \
  --password rootpass \
  --eval '
printjson(db.getSiblingDB("admin").createUser({
  user: "testuser",
  pwd: "testpass",
  roles: [ { role: "readWrite", db: "testdb" } ]
}));
'
  6. Insert a new document: 
    mongosh "mongodb://root@localhost:27017/admin?authMechanism=SCRAM-SHA-256" \
  --tls \
  --tlsCAFile ./certs/ca.pem \
  --tlsCertificateKeyFile ./certs/client.pem \
  --password rootpass \
  --eval '
const dbname = "testdb";
const coll = db.getSiblingDB(dbname).docs;
const doc = {
  test: "Welcome to TLS MongoDB running Minimus image",
  timestamp: new Date().toISOString()
};
print("✅ Inserting document:");
printjson(doc);
printjson(coll.insertOne(doc));
'
  7. Get all documents in a collection: 
    mongosh "mongodb://root@localhost:27017/admin?authMechanism=SCRAM-SHA-256" \
  --tls \
  --tlsCAFile ./certs/ca.pem \
  --tlsCertificateKeyFile ./certs/client.pem \
  --password rootpass \
  --eval '
const dbname = "testdb";
const coll = db.getSiblingDB(dbname).docs;
print("📄 All documents in", dbname + ".docs:");
coll.find().forEach(doc => printjson(doc));
'
  8. Delete a database: 
    mongosh "mongodb://root@localhost:27017/admin?authMechanism=SCRAM-SHA-256" \
  --tls \
  --tlsCAFile ./certs/ca.pem \
  --tlsCertificateKeyFile ./certs/client.pem \
  --password rootpass \
  --eval '
const dbname = "testdb";
const res = db.getSiblingDB(dbname).dropDatabase();
print("🗑️ Dropped database:", dbname);
printjson(res);
'