The reindex.ssl.certificate setting in Elasticsearch controls the SSL/TLS certificate used for secure communication during reindexing operations from remote clusters.
- Default value: None
- Possible values: Path to a PEM-encoded SSL/TLS certificate file
- Recommendations: Use a valid, up-to-date SSL certificate from a trusted Certificate Authority (CA)
This setting is used in conjunction with other SSL-related settings to establish secure connections when reindexing data from remote Elasticsearch clusters. It's particularly important when the remote cluster requires client certificate authentication.
Example Usage
To set the SSL certificate for reindexing operations:
PUT /_cluster/settings
{
"persistent": {
"reindex.ssl.certificate": "/path/to/client.crt"
}
}
Changing this setting is necessary when you need to reindex data from a remote cluster that uses SSL/TLS and requires client certificate authentication. The effect of this change is to enable secure communication with the remote cluster during reindexing operations.
Common Issues and Misuses
- Incorrect file path or permissions
- Using an expired or invalid certificate
- Mismatching certificate and private key
- Not configuring all required SSL settings (e.g.,
reindex.ssl.key)
Do's and Don'ts
Do's:
- Use a valid, up-to-date certificate from a trusted CA
- Ensure the certificate file has proper read permissions for the Elasticsearch process
- Keep your SSL certificates and keys in a secure location
- Regularly update and rotate your certificates
Don'ts:
- Don't use self-signed certificates in production environments
- Don't share or expose your private keys
- Don't forget to configure other required SSL settings
- Don't use plain HTTP for reindexing operations in production environments
Frequently Asked Questions
Q: How do I generate a client certificate for reindexing?
A: You can generate a client certificate using OpenSSL or a similar tool. First, create a private key, then generate a Certificate Signing Request (CSR), and finally have it signed by a CA or create a self-signed certificate.
Q: Can I use the same certificate for multiple Elasticsearch clusters?
A: Yes, you can use the same client certificate for multiple clusters as long as it's trusted by all the remote clusters you're connecting to. However, for better security, it's recommended to use separate certificates for different environments or purposes.
Q: What happens if the certificate expires during a reindexing operation?
A: If the certificate expires during a reindexing operation, the operation will fail with an SSL handshake error. It's important to monitor certificate expiration dates and renew them before they expire.
Q: Do I need to restart Elasticsearch after changing the reindex.ssl.certificate setting?
A: No, you don't need to restart Elasticsearch. The setting can be changed dynamically using the Cluster Settings API, and the new certificate will be used for subsequent reindexing operations.
Q: Can I use environment variables or Elasticsearch keystore for storing the certificate path?
A: Yes, you can use environment variables or the Elasticsearch keystore to securely store and reference the certificate path. This is especially useful for maintaining consistency across different environments and for security best practices.
