Ansible Role opensearch

This role installs and configures OpenSearch, either as a single-node instance or as a multi-node cluster.

Note that this role does NOT let you specify a particular OpenSearch version. It simply installs the latest available OpenSearch version from the repos configured in the system. If you want or need to install a specific version, use the opensearch__version__host_var / opensearch__version__group_var variables.

Supported versions:

• 1.x

• 2.x

Hints for configuring TLS:

• The admin certificate must not be the same as a node certificate. Using the same certificate results in: Seems you use a node certificate. This is not permitted, you have to use a client certificate and register it as admin_dn in opensearch.yml

• Node certificates must either have extendedKeyUsage = serverAuth, clientAuth (TLS Web Server Authentication, TLS Web Client Authentication, respectively) set, or no Extended Key Usage at all. Otherwise securityadmin.sh fails with: ERR: An unexpected SSLHandshakeException occured: Received fatal alert: certificate_unknown

Mandatory Requirements

• Enable the official OpenSearch repository. This can be done using the linuxfabrik.lfops.repo_opensearch role.

If you use the opensearch playbook, this is automatically done for you.

Single-Node Setup

For a single-node setup, no special configuration is needed beyond the mandatory variables. When opensearch__discovery_seed_hosts is not set, OpenSearch 2.x automatically runs in single-node mode (discovery.type: single-node). After installation, verify that OpenSearch is running (see Post-Installation Steps below).

Tags

opensearch

• Installs OpenSearch.

• Deploys all configuration files.

• Deploys TLS certificates and runs securityadmin.sh (if security plugin is enabled).

• Manages the state of the OpenSearch service.

• Triggers: opensearch.service restart.

opensearch:configure

• Deploys /etc/opensearch/opensearch.yml.

• Deploys /etc/sysconfig/opensearch.

• Deploys internal users configuration (if security plugin is enabled).

• Triggers: opensearch.service restart.

opensearch:generate_certs

• Generates self-signed TLS certificates on the Ansible controller using the SearchGuard TLS Tool.

• Triggers: none.

opensearch:state

• Manages the state of the OpenSearch service (systemctl enable/disable --now).

• Triggers: none.

opensearch:user

• Manages internal users (generates hashed passwords, deploys internal_users.yml).

• Triggers: opensearch.service restart, securityadmin.sh.

Mandatory Role Variables

opensearch__opensearch_initial_admin_password

• For new installations of OpenSearch 2.12 and later, a custom admin password is required. Minimum 8 characters, must contain at least one uppercase letter, one lowercase letter, one digit, and one special character.

• Type: String.

Example:

# mandatory
opensearch__opensearch_initial_admin_password: 'linuxfabrik'

Post-Installation Steps

After setting up a single node or cluster, verify that OpenSearch is running:

curl 'https://localhost:9200' --user admin:your-password --insecure

Setting Up an OpenSearch Cluster

This role supports creating a multi-node OpenSearch cluster using manual certificate distribution. TLS certificates are generated beforehand and distributed to all nodes via Ansible. The security plugin is configured with the certificate distinguished names of all cluster members.

All cluster nodes must:

• Have the same opensearch__cluster_name__*_var configured

• Be able to communicate with each other (configure opensearch__network_host accordingly, e.g., 0.0.0.0 or a specific IP)

• Have opensearch__discovery_seed_hosts set to the list of all cluster nodes from the start

• Have matching TLS certificates (same CA, correct node DNs)

Generate TLS Certificates

You have two options:

Option A: Use the built-in certificate generator (recommended for testing)

This role includes a convenience feature to generate self-signed certificates using the SearchGuard TLS Tool. The certificates are generated on the Ansible controller.

Configure the certificate generation variables:

opensearch__generate_certs_admin_cn: 'OpenSearch Admin'
opensearch__generate_certs_base_dn: 'OU=Secure Services,O=ACME,ST=Zurich,C=CH'
opensearch__generate_certs_ca_cn: 'OpenSearch Self-signed RootCA'
opensearch__generate_certs_nodes:
  - cn: 'node1.example.com'
    ip: '192.0.2.10'
  - cn: 'node2.example.com'
    ip: '192.0.2.11'
  - cn: 'node3.example.com'
    ip: '192.0.2.12'

Run the certificate generation:

ansible-playbook --inventory inventory linuxfabrik.lfops.opensearch --tags opensearch:generate_certs

The generated certificates and the SearchGuard TLS Tool config are placed in /tmp/opensearch-certs/. Copy them to your Ansible inventory for deployment.

Option B: Provide your own certificates

Place your certificates in the inventory and reference them via the opensearch__plugins_security_* variables (see Optional Role Variables below).

Bootstrap the First Node

Set the cluster variables in your inventory:

# group_vars for the OpenSearch cluster group
opensearch__cluster_name__group_var: 'my-cluster'
opensearch__discovery_seed_hosts:
  - 'node1.example.com'
  - 'node2.example.com'
  - 'node3.example.com'
opensearch__network_host: '0.0.0.0'
opensearch__plugins_security_authcz_admin_dns:
  - 'CN=OpenSearch Admin,OU=Secure Services,O=ACME,ST=Zurich,C=CH'
opensearch__plugins_security_nodes_dns:
  - 'CN=node1.example.com,OU=Secure Services,O=ACME,ST=Zurich,C=CH'
  - 'CN=node2.example.com,OU=Secure Services,O=ACME,ST=Zurich,C=CH'
  - 'CN=node3.example.com,OU=Secure Services,O=ACME,ST=Zurich,C=CH'
# TLS certificates (example using file lookups)
opensearch__plugins_security_root_ca: '{{ lookup("ansible.builtin.file",
    "{{ inventory_dir }}/group_vars/my_opensearch_cluster_group/files/etc/opensearch/root-ca.pem")
  }}'
opensearch__plugins_security_admin_certificate: '{{ lookup("ansible.builtin.file",
    "{{ inventory_dir }}/group_vars/my_opensearch_cluster_group/files/etc/opensearch/admin.pem")
  }}'
opensearch__plugins_security_admin_certificate_key: '{{ lookup("ansible.builtin.file",
    "{{ inventory_dir }}/group_vars/my_opensearch_cluster_group/files/etc/opensearch/admin.key")
  }}'
opensearch__plugins_security_http_certificate: '{{ lookup("ansible.builtin.file",
    "{{ inventory_dir }}/host_vars/{{ inventory_hostname }}/files/etc/opensearch/node_http.pem")
  }}'
opensearch__plugins_security_http_certificate_key: '{{ lookup("ansible.builtin.file",
    "{{ inventory_dir }}/host_vars/{{ inventory_hostname }}/files/etc/opensearch/node_http.key")
  }}'
opensearch__plugins_security_transport_certificate: '{{ lookup("ansible.builtin.file",
    "{{ inventory_dir }}/host_vars/{{ inventory_hostname }}/files/etc/opensearch/node_transport.pem")
  }}'
opensearch__plugins_security_transport_certificate_key: '{{ lookup("ansible.builtin.file",
    "{{ inventory_dir }}/host_vars/{{ inventory_hostname }}/files/etc/opensearch/node_transport.key")
  }}'

Deploy the first node with opensearch__cluster_initial_cluster_manager_nodes:

ansible-playbook --inventory inventory linuxfabrik.lfops.opensearch \
  --limit node1.example.com \
  --extra-vars='{"opensearch__cluster_initial_cluster_manager_nodes": ["node1.example.com"]}'

Important: Only include the first node in opensearch__cluster_initial_cluster_manager_nodes. Including nodes that do not exist yet causes the first node to wait indefinitely and the cluster will not form.

Verify Cluster State

curl 'https://node1.example.com:9200/_cluster/health?pretty' --user admin:your-password --insecure
curl 'https://node1.example.com:9200/_cat/nodes?v' --user admin:your-password --insecure

Deploy Additional Nodes

Deploy remaining nodes without opensearch__cluster_initial_cluster_manager_nodes:

ansible-playbook --inventory inventory linuxfabrik.lfops.opensearch \
  --limit node2.example.com,node3.example.com

The nodes will automatically join the existing cluster using opensearch__discovery_seed_hosts.

Clear Initial Cluster Manager Nodes Configuration

After all nodes have joined, remove the cluster.initial_cluster_manager_nodes setting from the first node:

ansible-playbook --inventory inventory linuxfabrik.lfops.opensearch \
  --limit node1.example.com \
  --tags opensearch:configure

This prevents issues when the first node is restarted later.

Verify Complete Cluster

Verify all nodes have joined the cluster:

curl 'https://node1.example.com:9200/_cluster/health?pretty' --user admin:your-password --insecure
curl 'https://node1.example.com:9200/_cat/nodes?v' --user admin:your-password --insecure

The status should be green with all nodes listed.

Adding a New Node to an Existing Cluster

1. Generate certificates for the new node using the same CA as the existing cluster.

2. Add the certificate files to your Ansible inventory.

3. Add the new node’s DN to opensearch__plugins_security_nodes_dns in group_vars.

4. Add the new node to opensearch__discovery_seed_hosts in group_vars.

5. Create host_vars for the new node with a unique opensearch__node_name.

6. Deploy the new node:

ansible-playbook --inventory inventory linuxfabrik.lfops.opensearch --limit new-node.example.com

7. Roll out the updated opensearch__discovery_seed_hosts and opensearch__plugins_security_nodes_dns to all cluster nodes:

ansible-playbook --inventory inventory linuxfabrik.lfops.opensearch --tags opensearch:configure

Optional Role Variables - General

Only optional if opensearch__plugins_security_disabled is true.

opensearch__action_auto_create_index__host_var / opensearch__action_auto_create_index__group_var

• Automatic index creation allows any index to be created automatically.

• For the usage in host_vars / group_vars (can only be used in one group at a time).

• Type: Bool.

• Default: true

opensearch__cluster_name__host_var / opensearch__cluster_name__group_var

• A descriptive name for your cluster.

• For the usage in host_vars / group_vars (can only be used in one group at a time).

• Type: String.

• Default: 'my-application'

opensearch__internal_users__host_var / opensearch__internal_users__group_var

• Internal users that can access OpenSearch via HTTP Basic Auth.

• Type: List of dictionaries.

• Default: []

• Subkeys:

  • username:

    • Mandatory. Username.

    • Type: String.

  • password:

    • Mandatory. Password.

    • Type: String.

  • backend_roles:

    • Optional. Backend roles.

    • Type: List of strings.

    • Default: []

  • state:

    • Optional. State of the user. Either present or absent.

    • Type: String.

    • Default: 'present'

opensearch__network_host

• Set the bind address to a specific IP.

• Type: String.

• Default: '127.0.0.1'

opensearch__node_name

• A descriptive name for the node.

• Type: String.

• Default: '{{ ansible_facts["nodename"] }}'

opensearch__path_data__host_var / opensearch__path_data__group_var

• Path to directory where to store the data. Directory will be created.

• For the usage in host_vars / group_vars (can only be used in one group at a time).

• Type: String.

• Default: '/var/lib/opensearch'

opensearch__plugins_security_admin_certificate

• The ASCII-armored public PEM admin certificate.

• Type: String.

• Default: unset

opensearch__plugins_security_admin_certificate_key

• The ASCII-armored private PEM admin key.

• Type: String.

• Default: unset

opensearch__plugins_security_allow_unsafe_democertificates

• When set to true, OpenSearch starts up with demo certificates. These certificates are issued only for demo purposes. See security settings.

• Type: Bool.

• Default: false

opensearch__plugins_security_authcz_admin_dns

• List of distinguished names of certificates that should have admin permissions.

• Type: List of strings.

• Default: []

opensearch__plugins_security_disabled

• Enables or disables the OpenSearch security plugin, which offers encryption, authentication, access control as well as audit logging and compliance.

• Type: Bool.

• Default: false

opensearch__plugins_security_http_certificate

• The ASCII-armored public PEM HTTP certificate.

• Type: String.

• Default: unset

opensearch__plugins_security_http_certificate_key

• The ASCII-armored private PEM HTTP key.

• Type: String.

• Default: unset

opensearch__plugins_security_root_ca

• The ASCII-armored public PEM root CA certificate.

• Type: String.

• Default: unset

opensearch__plugins_security_transport_certificate

• The ASCII-armored public PEM transport certificate.

• Type: String.

• Default: unset

opensearch__plugins_security_transport_certificate_key

• The ASCII-armored private PEM transport key.

• Type: String.

• Default: unset

opensearch__plugins_security_transport_enforce_hostname_verification

• See hostname verification.

• Type: Bool.

• Default: true

opensearch__plugins_security_transport_resolve_hostname

• See hostname verification.

• Type: Bool.

• Default: true

opensearch__service_enabled

• Enables or disables the OpenSearch service, analogous to systemctl enable/disable --now.

• Type: Bool.

• Default: true

opensearch__version__host_var / opensearch__version__group_var

• The version of OpenSearch to install. If unset, the latest version will be installed. Note that the version format is OS-dependent: use -2.15.0 on RHEL and =2.15.0* on Debian.

• For the usage in host_vars / group_vars (can only be used in one group at a time).

• Type: String.

• Default: unset

Example:

# optional
opensearch__action_auto_create_index__host_var: false
opensearch__cluster_name__host_var: 'my-cluster'
opensearch__internal_users__host_var:
  - username: 'opensearch-admin'
    password: 'linuxfabrik'
    backend_roles:
      - 'admin'
opensearch__network_host: '127.0.0.1'
opensearch__node_name: 'my-node1'
opensearch__path_data__host_var: '/var/lib/opensearch'
opensearch__plugins_security_admin_certificate: '{{ lookup("ansible.builtin.file",
    "{{ inventory_dir }}/group_vars/my_opensearch_cluster_group/files/etc/opensearch/admin.pem")
  }}'
opensearch__plugins_security_admin_certificate_key: '{{ lookup("ansible.builtin.file",
    "{{ inventory_dir }}/group_vars/my_opensearch_cluster_group/files/etc/opensearch/admin.key")
  }}'
opensearch__plugins_security_allow_unsafe_democertificates: false
opensearch__plugins_security_authcz_admin_dns:
  - 'CN=OpenSearch Admin,OU=Secure Services,O=ACME,ST=Zurich,C=CH'
opensearch__plugins_security_disabled: false
opensearch__plugins_security_http_certificate: '{{ lookup("ansible.builtin.file",
    "{{ inventory_dir }}/host_vars/{{ inventory_hostname }}/files/etc/opensearch/node_http.pem")
  }}'
opensearch__plugins_security_http_certificate_key: '{{ lookup("ansible.builtin.file",
    "{{ inventory_dir }}/host_vars/{{ inventory_hostname }}/files/etc/opensearch/node_http.key")
  }}'
opensearch__plugins_security_root_ca: '{{ lookup("ansible.builtin.file",
    "{{ inventory_dir }}/group_vars/my_opensearch_cluster_group/files/etc/opensearch/root-ca.pem")
  }}'
opensearch__plugins_security_transport_certificate: '{{ lookup("ansible.builtin.file",
    "{{ inventory_dir }}/host_vars/{{ inventory_hostname }}/files/etc/opensearch/node_transport.pem")
  }}'
opensearch__plugins_security_transport_certificate_key: '{{ lookup("ansible.builtin.file",
    "{{ inventory_dir }}/host_vars/{{ inventory_hostname }}/files/etc/opensearch/node_transport.key")
  }}'
opensearch__plugins_security_transport_enforce_hostname_verification: false
opensearch__plugins_security_transport_resolve_hostname: true
opensearch__service_enabled: false
opensearch__version__host_var: '-2.15.0' # rhel
opensearch__version__host_var: '=2.15.0*' # debian

Optional Role Variables - Cluster Configuration

opensearch__cluster_initial_cluster_manager_nodes

• A list of initial master-eligible nodes. The entries have to match the opensearch__node_name. Only use this during initial cluster bootstrap via --extra-vars. Never set this permanently in inventory. After the first successful cluster start, all subsequent runs should omit this variable.

• Type: List of strings.

• Default: unset

opensearch__discovery_seed_hosts

• A list of IPs or hostnames that point to all master-eligible nodes of the cluster. The port defaults to 9300 but can be overwritten by appending it to the hostname.

• Type: List of strings.

• Default: unset

opensearch__plugins_security_nodes_dns

• List of distinguished names of all cluster member certificates.

• Type: List of strings.

• Default: []

Example:

# cluster configuration
opensearch__discovery_seed_hosts:
  - 'node1.example.com'
  - 'node2.example.com'
  - 'node3.example.com:9301'
opensearch__plugins_security_nodes_dns:
  - 'CN=node1.example.com,OU=Secure Services,O=ACME,ST=Zurich,C=CH'
  - 'CN=node2.example.com,OU=Secure Services,O=ACME,ST=Zurich,C=CH'
  - 'CN=node3.example.com,OU=Secure Services,O=ACME,ST=Zurich,C=CH'

TLS Certificate Generation Variables

These variables are only needed when using the built-in certificate generator (see „Setting Up an OpenSearch Cluster“ above). The tasks run against the Ansible controller. Internally, the SearchGuard TLS Tool is used, with the generated config at /tmp/opensearch-certs/config/{{ inventory_hostname }}-tlsconfig.yml.

opensearch__generate_certs_admin_cn

• The common name of the admin certificate.

• Type: String.

• Default: 'OpenSearch Admin'

opensearch__generate_certs_base_dn

• The base distinguished name for all the self-signed certificates.

• Type: String.

• Default: 'OU=Secure Services,O=ACME,ST=Zurich,C=CH'

opensearch__generate_certs_ca_cn

• The common name of the CA certificate.

• Type: String.

• Default: 'OpenSearch Self-signed RootCA'

opensearch__generate_certs_nodes

• List of dictionaries for the node certificates.

• Type: List of dictionaries.

• Default: []

• Subkeys:

  • cn:

    • Mandatory. Common name of the node certificate.

    • Type: String.

  • ip:

    • Mandatory. IP address of the node.

    • Type: String.

Example:

# tls certificate generation
opensearch__generate_certs_admin_cn: 'OpenSearch Admin'
opensearch__generate_certs_base_dn: 'OU=Secure Services,O=ACME,ST=Zurich,C=CH'
opensearch__generate_certs_ca_cn: 'OpenSearch Self-signed RootCA'
opensearch__generate_certs_nodes:
  - cn: 'node1.example.com'
    ip: '192.0.2.10'
  - cn: 'node2.example.com'
    ip: '192.0.2.11'
  - cn: 'node3.example.com'
    ip: '192.0.2.12'

License

The Unlicense

Author Information

Linuxfabrik GmbH, Zurich