Fluent Bit TLS handshake failure

What is Fluent Bit TLS handshake failure

Understanding Fluent Bit

Fluent Bit is a lightweight and high-performance log processor and forwarder that allows you to collect data and logs from different sources, unify them, and send them to multiple destinations. It is designed to handle data collection and processing efficiently, making it an ideal choice for cloud and containerized environments.

Identifying the Symptom: TLS Handshake Failure

When using Fluent Bit, you might encounter a TLS handshake failure. This issue typically manifests as an error message indicating that the TLS handshake process could not be completed successfully. This error prevents Fluent Bit from establishing a secure connection with the destination server.

Common Error Messages

"TLS handshake failed" "SSL routines:ssl3_get_record:wrong version number" "SSL routines:ssl3_read_bytes:sslv3 alert handshake failure"

Exploring the Issue: TLS Configuration Problems

The TLS handshake failure in Fluent Bit is often due to misconfigurations in the TLS setup. This can include incorrect certificates, protocol mismatches, or unsupported cipher suites. These issues prevent the client and server from agreeing on a secure communication channel.

Root Causes

Incorrect or expired certificates Protocol version mismatches (e.g., server supports TLS 1.2, but client uses TLS 1.1) Unsupported or mismatched cipher suites

Steps to Resolve TLS Handshake Failures

To resolve TLS handshake failures in Fluent Bit, follow these steps:

1. Verify Certificates

Ensure that the certificates used by Fluent Bit are valid and correctly configured. Check the certificate chain and ensure that the root and intermediate certificates are trusted by the destination server.

openssl verify -CAfile ca.pem client-cert.pem

2. Check Protocol Compatibility

Ensure that both the client (Fluent Bit) and the server support the same TLS protocol versions. You can specify the protocol version in Fluent Bit's configuration:

[OUTPUT] Name es Match * Host your-elasticsearch-host Port 9200 tls On tls.verify On tls.version TLSv1_2

3. Validate Cipher Suites

Ensure that the cipher suites supported by Fluent Bit are compatible with those supported by the server. You can test the server's supported cipher suites using:

openssl s_client -connect your-server:443 -tls1_2

Additional Resources

For more detailed information on configuring TLS in Fluent Bit, refer to the official Fluent Bit documentation. Additionally, you can explore the OpenSSL documentation for more insights into certificate and protocol management.