Secure communication with Elasticsearch

To secure the communication between APM Server and Elasticsearch, you can use HTTPS and basic authentication. Basic authentication for Elasticsearch is available when you enable X-Pack security (see Securing the Elastic Stack and configure APM Server to use security features). If you aren’t using X-Pack security, you can use a web proxy instead.

When sending data to a secured cluster through the elasticsearch output, APM Server can use any of the following authentication methods:

Basic authentication credentials (username and password).
Token-based API authentication.
A client certificate.

Authentication is specified in the APM Server configuration file:

To use basic authentication, specify the username and password settings under output.elasticsearch. For example:

output.elasticsearch:
  hosts: ["https://myEShost:9200"]
  username: "apm_writer" 
  password: "YOUR_PASSWORD"

	This user needs the privileges required to publish events to Elasticsearch. To create a user like this, see Create a writer user.
	This example shows a hard-coded password, but you should store sensitive values in the secrets keystore.

To use token-based API key authentication, specify the api_key under output.elasticsearch. For example:
```
output.elasticsearch:
  hosts: ["https://myEShost:9200"]
  api_key: "KnR6yE41RrSowb0kQ0HWoA" 
```
This API key must have the privileges required to publish events to Elasticsearch. To create an API key like this, see Grant access using API keys.

To use Public Key Infrastructure (PKI) certificates to authenticate users, specify the certificate and key settings under output.elasticsearch. For example:

output.elasticsearch:
  hosts: ["https://myEShost:9200"]
  ssl.certificate: "/etc/pki/client/cert.pem" 
  ssl.key: "/etc/pki/client/cert.key"

	The path to the certificate for SSL client authentication
	The client certificate key

These settings assume that the distinguished name (DN) in the certificate is mapped to the appropriate roles in the role_mapping.yml file on each node in the Elasticsearch cluster. For more information, see Using role mapping files.

By default, APM Server uses the list of trusted certificate authorities (CA) from the operating system where APM Server is running. If the certificate authority that signed your node certificates is not in the host system’s trusted certificate authorities list, you need to add the path to the .pem file that contains your CA’s certificate to the APM Server configuration. This will configure APM Server to use a specific list of CA certificates instead of the default list from the OS.

Here is an example configuration:

output.elasticsearch:
  hosts: ["https://myEShost:9200"]
  ssl.certificate_authorities: 
    - /etc/pki/my_root_ca.pem
    - /etc/pki/my_other_ca.pem
  ssl.certificate: "/etc/pki/client.pem" 
  ssl.key: "/etc/pki/key.pem"

	Specify the path to the local `.pem` file that contains your Certificate Authority’s certificate. This is needed if you use your own CA to sign your node certificates.
	The path to the certificate for SSL client authentication
	The client certificate key

For any given connection, the SSL/TLS certificates must have a subject that matches the value specified for hosts, or the SSL handshake fails. For example, if you specify hosts: ["foobar:9200"], the certificate MUST include foobar in the subject (CN=foobar) or as a subject alternative name (SAN). Make sure the hostname resolves to the correct IP address. If no DNS is available, then you can associate the IP address with your hostname in /etc/hosts (on Unix) or C:\Windows\System32\drivers\etc\hosts (on Windows).

Learn more about secure communication

edit

More information on sending data to a secured cluster is available in the configuration reference:

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