Configure TLS

TLS/SSL layer is very important not only for securing your connections but also to increase a chance to establish Websocket connection.

tip

In most situations you better put TLS termination task on your reverse proxy/load balancing software such as Nginx. This can be a good thing for performance.

There are situations though when you want to serve secure connections by Centrifugo itself.

There are two ways to do this: using TLS certificate cert and key files that you've got from your CA provider or using automatic certificate handling via ACME provider (only Let's Encrypt at this moment).

Using crt and key files

In first way you already have cert and key files. For development you can create self-signed certificate - see this instruction as example.

config.json

{
  ...
  "tls": true,
  "tls_key": "server.key",
  "tls_cert": "server.crt"
}

And run:

./centrifugo --config=config.json

Automatic certificates

For automatic certificates from Let's Encrypt add into configuration file:

config.json

{
  ...
  "tls_autocert": true,
  "tls_autocert_host_whitelist": "www.example.com",
  "tls_autocert_cache_dir": "/tmp/certs",
  "tls_autocert_email": "[email protected]",
  "tls_autocert_http": true,
  "tls_autocert_http_addr": ":80"
}

tls_autocert (boolean) says Centrifugo that you want automatic certificate handling using ACME provider.

tls_autocert_host_whitelist (string) is a string with your app domain address. This can be comma-separated list. It's optional but recommended for extra security.

tls_autocert_cache_dir (string) is a path to a folder to cache issued certificate files. This is optional but will increase performance.

tls_autocert_email (string) is optional - it's an email address ACME provider will send notifications about problems with your certificates.

tls_autocert_http (boolean) is an option to handle http_01 ACME challenge on non-TLS port.

tls_autocert_http_addr (string) can be used to set address for handling http_01 ACME challenge (default is :80)

When configured correctly and your domain is valid (localhost will not work) - certificates will be retrieved on first request to Centrifugo.

Also Let's Encrypt certificates will be automatically renewed.

There are two options that allow Centrifugo to support TLS client connections from older browsers such as Chrome 49 on Windows XP and IE8 on XP:

• tls_autocert_force_rsa - this is a boolean option, by default false. When enabled it forces autocert manager generate certificates with 2048-bit RSA keys.
• tls_autocert_server_name - string option, allows to set server name for client handshake hello. This can be useful to deal with old browsers without SNI support - see comment

grpc_api_tls_disable boolean flag allows to disable TLS for GRPC API server but keep it on for HTTP endpoints.

uni_grpc_tls_disable boolean flag allows to disable TLS for GRPC uni stream server but keep it on for HTTP endpoints.

TLS for GRPC API

You can provide custom certificate files to configure TLS for GRPC API server.

• grpc_api_tls boolean flag enables TLS for GRPC API server, requires an X509 certificate and a key file
• grpc_api_tls_cert string provides a path to an X509 certificate file for GRPC API server
• grpc_api_tls_key string provides a path to an X509 certificate key for GRPC API server

TLS for GRPC unidirectional stream

You can provide custom certificate files to configure TLS for GRPC unidirectional stream endpoint.

• uni_grpc_tls boolean flag enables TLS for GRPC server, requires an X509 certificate and a key file
• uni_grpc_tls_cert string provides a path to an X509 certificate file for GRPC uni stream server
• uni_grpc_tls_key string provides a path to an X509 certificate key for GRPC uni stream server

Unified TLS config object

Centrifugo v5 started a migration to a new unified way to configure TLS for all parts of Centrifugo. Some reasoning may be found in this issue on GitHub.

caution

At this point we use a unified TLS configuration object only for some parts of Centrifugo, but planning to extend this to all TLS configurations in Centrifugo v6. We explicitly point to this config in feature descriptions at this stage.

New TLS config is an object that has the following structure.

TLSConfig

Option Name	Type	Description
enabled	bool	Turns on using TLS.
cert_pem	string	Certificate in PEM format.
cert_pem_b64	string	Certificate in base64 encoded PEM format.
cert_pem_file	string	Path to a file with certificate in PEM format.
key_pem	string	Key in PEM format.
key_pem_b64	string	Key in base64 encoded PEM format.
key_pem_file	string	Path to a file with key in PEM format.
server_ca_pem	string	Server root CA certificate in PEM format used by client to verify server's certificate during handshake.
server_ca_pem_b64	string	Server root CA certificate in base64 encoded PEM format.
server_ca_pem_file	string	Path to a file with server root CA certificate in PEM format.
client_ca_pem	string	Client CA certificate in PEM format used by server to verify client's certificate during handshake.
client_ca_pem_b64	string	Client CA certificate in base64 encoded PEM format.
client_ca_pem_file	string	Path to a file with client CA certificate in PEM format.
insecure_skip_verify	bool	Turns off server certificate verification.
server_name	string	Used to verify the hostname on the returned certificates.

• Source Priority: The configuration allows specifying TLS settings from multiple sources: file, base64 encoded PEM, and raw PEM. The sources are prioritized in the following order:
  1. File to PEM
  2. Base64 encoded PEM
  3. Raw PEM
• Single Source Usage: Users should ensure that only one source of configured values is used. For example, if both cert_pem_file and cert_pem are set, the file source (cert_pem_file) will be used, and the raw PEM (cert_pem) will be ignored.
• Server and Client CA: server_ca_pem and client_ca_pem are used for verifying the server and client certificates respectively during the TLS handshake.
• Insecure Option: The insecure_skip_verify option can be used to turn off server certificate verification, which is not recommended for production environments.
• Hostname Verification: The server_name is utilized to verify the hostname on the returned certificates, providing an additional layer of security.

So in the configuration the usage of new TLS config may be like this:

config.json

{
  ...
  "proxy_grpc_tls": {
    "enabled": true,
    "cert_pem_file": "/path/to/cert.pem",
    "key_pem_file": "/path/to/key.pem"
  },
}