To secure your CockroachDB cluster's inter-node and client-node communication, you need to provide a Certificate Authority (CA) certificate that has been used to sign keys and certificates (SSLs) for:

  • Nodes
  • Clients
  • Admin UI (optional)

To create these certificates and keys, use the cockroach cert commands with the appropriate subcommands and flags, use openssl commands, or use a custom CA (for example, a public CA or your organizational CA).

This document discusses the following advanced use cases for using security certificates with CockroachDB:

Approach Use case description
UI certificate and key When you want to access the Admin UI for a secure cluster and avoid clicking through a warning message to get to the UI.
Split-node certificate When your organizational CA requires you to have separate certificates for the node's incoming connections (from SQL and Admin UI clients, and from other CockroachDB nodes) and for outgoing connections to other CockroachDB nodes.
Split-CA certificates When you have multiple CockroachDB clusters and need to restrict access to clients from accessing the other cluster.

Accessing the Admin UI for a secure cluster

On accessing the Admin UI for a secure cluster, your web browser will consider the CockroachDB-issued certificate invalid, because the browser hasn't been configured to trust the CA that issued the certificate.

For secure clusters, you can avoid getting the warning message by using a certificate issued by a public CA whose certificates are trusted by browsers, in addition to the CockroachDB-created certificates:

  1. Request a certificate from a public CA (for example, Let's Encrypt). The certificate must have the IP addresses and DNS names used to reach the Admin UI listed in the Subject Alternative Name field.
  2. Rename the certificate and key as ui.crt and ui.key.
  3. Add the ui.crt and ui.key to the certificate directory. ui.key must not have group or world permissions (maximum permissions are 0700, or rwx------). You can disable this check by setting the environment variable COCKROACH_SKIP_KEY_PERMISSION_CHECK=true.
  4. For nodes that are already running, load the ui.crt certificate without restarting the node by issuing a SIGHUP signal to the cockroach process:
    copy
    icon/buttons/copy
   pkill -SIGHUP -x cockroach

The SIGHUP signal must be sent by the same user running the process (e.g., run with sudo if the cockroach process is running under user root).

Node key and certificates

A node must have the following files with file names as specified in the table:

File name File usage
ca.crt CA certificate created using the cockroach cert command.
node.crt Server certificate created using the cockroach cert command.

node.crt must have CN=node and the list of IP addresses and DNS names listed in Subject Alternative Name field.

Must be signed by ca.crt.
node.key Server key created using the cockroach cert command.
ui.crt UI certificate signed by the public CA. ui.crt must have the IP addresses and DNS names used to reach the Admin UI listed in Subject Alternative Name.
ui.key UI key corresponding to ui.crt.

Client key and certificates

A client must have the following files with file names as specified in the table:

File name File usage
ca.crt CA certificate created using the cockroach cert command.
client.<user>.crt Client certificate for <user> (e.g., client.root.crt for user root).

Each client.<user>.crt must have CN=<user> (for example, CN=marc for client.marc.crt)

Must be signed by ca.crt.
client.<user>.key Client key created using the cockroach cert command.

Split node certificates

The node certificate discussed in the cockroach cert command documentation is multifunctional, which means the same certificate is presented for the node's incoming connections (from SQL and Admin UI clients, and from other CockroachDB nodes) and for outgoing connections to other CockroachDB nodes. To make the certificate multi-functional, the node.crt created using the cockroach cert command has CN=node and the list of IP addresses and DNS names listed in Subject Alternative Name field. This works if you are also using the CockroachDB CA created using the cockroach cert command. However, if you need to use an external public CA or your own organizational CA, the CA policy might not allow it to sign a server certificate containing a CN that is not an IP address or domain name.

To get around this issue, you can split the node key and certificate into two:

  • node.crt and node.key: node.crt is used as the server certificate when a node receives incoming connections from clients and other nodes. All IP addresses and DNS names for the node must be listed in the Subject Alternative Name field.
  • client.node.crt and client.node.key: client.node.crt is used as the client certificate when making connections to other nodes. client.node.crt must have CN=node.

Node key and certificates

A node must have the following files with file names as specified in the table:

File name File usage
ca.crt CA certificate issued by the public CA or your organizational CA.
node.crt Server certificate used when a node receives incoming connections from clients and other nodes.

All IP addresses and DNS names for the node must be listed in Subject Alternative Name.

Must be signed by ca.crt.
node.key Server key corresponding to node.crt.
client.node.crt Client certificate when making connections to other nodes.

Must have CN=node.

Must be signed by ca.crt.
client.node.key Client key corresponding to client.node.crt.

Optionally, if you have a certificate issued by a public CA to securely access the Admin UI, you need to place the certificate and key (ui.crt and ui.key respectively) in the directory specified by the --certs-dir flag.

Client key and certificates

A client must have the following files with file names as specified in the table:

File name File usage
ca.crt CA certificate issued by the public CA or your organizational CA.
client.<user>.crt Client certificate for <user> (e.g., client.root.crt for user root).

Each client.<user>.crt must have CN=<user> (for example, CN=marc for client.marc.crt)

Must be signed by ca.crt.
client.<user>.key Client key corresponding to client.<user>.crt.

Split CA certificates

Warning:

We do not recommend you use split CA certificates unless your organizational security practices mandate you to do so.

If you need to use separate CAs to sign node certificates and client certificates, then you need two CAs and their respective certificates and keys: ca.crt and ca-client.crt.

Node key and certificates

A node must have the following files with file names as specified in the table:

File name File usage
ca.crt CA certificate to verify node certificates.
ca-client.crt CA certificate to verify client certificates.
node.crt Server certificate used when a node receives incoming connections from clients and other nodes.

All IP addresses and DNS names for the node must be listed in Subject Alternative Name.

Must be signed by ca.crt.
node.key Server key corresponding to node.crt.
client.node.crt Client certificate when making connections to other nodes. This certificate must be signed using ca-client.crt

Must have CN=node.
client.node.key Client key corresponding to client.node.crt.

Optionally, if you have a certificate issued by a public CA to securely access the Admin UI, you need to place the certificate and key (ui.crt and ui.key respectively) in the directory specified by the --certs-dir flag.

Client key and certificates

A client must have the following files with file names as specified in the table:

File name File usage
ca.crt CA certificate.
client.<user>.crt Client certificate for <user> (e.g., client.root.crt for user root).

Each client.<user>.crt must have CN=<user> (for example, CN=marc for client.marc.crt).

Must be signed by ca-client.crt.
client.<user>.key Client key corresponding to client.<user>.crt.

See also



Yes No