Chef 12: Fix Untrusted Self Signed Certificates
// Chef Blog
Scenario: You've started up a brand new Chef Server using version 12, and you have installed Chef 12 on your local system. You log into the Management Console to create a user and organization (or do this with the command-line
chef-server-ctl commands), and you're ready to rock with this knife.rb:
node_name 'jtimberman' client_key 'jtimberman.pem' validation_client_name 'tester-validator' validation_key 'tester-validator.pem' chef_server_url 'https://chef-server.example.com/organizations/tester'
However, when you try to check things out with knife:
% knife client list ERROR: SSL Validation failure connecting to host: chef-server.example.com - SSL_connect returned=1 errno=0 state=SSLv3 read server certificate B: certificate verify failed ERROR: OpenSSL::SSL::SSLError: SSL_connect returned=1 errno=0 state=SSLv3 read server certificate B: certificate verify failed
This is because Chef client 12 has SSL verification enabled by default for all requests. Since the certificate generated by the Chef Server 12 installation is self-signed, there isn't a signing CA that can be verified, and this fails. Never fear intrepid user, for you can get the SSL certificate from the server and store it as a "trusted" certificate. To find out how, use
knife ssl check.
Connecting to host chef-server.example.com:443 ERROR: The SSL certificate of chef-server.example.com could not be verified Certificate issuer data: /C=US/ST=WA/L=Seattle/O=YouCorp/OU=Operations/CN=chef-server.example.com/emailAddressemail@example.com Configuration Info: OpenSSL Configuration: * Version: OpenSSL 1.0.1j 15 Oct 2014 * Certificate file: /opt/chefdk/embedded/ssl/cert.pem * Certificate directory: /opt/chefdk/embedded/ssl/certs Chef SSL Configuration: * ssl_ca_path: nil * ssl_ca_file: nil * trusted_certs_dir: "/Users/jtimberman/Downloads/chef-repo/.chef/trusted_certs" TO FIX THIS ERROR: If the server you are connecting to uses a self-signed certificate, you must configure chef to trust that server's certificate. By default, the certificate is stored in the following location on the host where your chef-server runs: /var/opt/chef-server/nginx/ca/SERVER_HOSTNAME.crt Copy that file to your trusted_certs_dir (currently: /Users/jtimberman/Downloads/chef-repo/.chef/trusted_certs) using SSH/SCP or some other secure method, then re-run this command to confirm that the server's certificate is now trusted.
(note, at the time of writing, this chef-server location is incorrect, it's
There is a
fetch plugin for
knife too. Let's download the certificate to the automatically preconfigured trusted certificate location mentioned in the output above.
% knife ssl fetch WARNING: Certificates from chef-server.example.com will be fetched and placed in your trusted_cert directory (/Users/jtimberman/Downloads/chef-repo/.chef/trusted_certs). Knife has no means to verify these are the correct certificates. You should verify the authenticity of these certificates after downloading. Adding certificate for chef-server.example.com in /Users/jtimberman/Downloads/chef-repo/.chef/trusted_certs/chef-server.example.com.crt
The certificate should be verified that what was downloaded is in fact the same as the certificate on the Chef Server. For example, I compared SHA256 checksums:
% ssh firstname.lastname@example.org sudo sha256sum /var/opt/opscode/nginx/ca/chef-server.example.com.crt 043728b55144861ed43a426c67addca357a5889158886aee50685cf1422b5ebf/var/opt/opscode/nginx/ca/chef-server.example.com.crt % gsha256sum .chef/trusted_certs/chef-server.example.com.crt 043728b55144861ed43a426c67addca357a5889158886aee50685cf1422b5ebf.chef/trusted_certs/chef-server.example.com.crt
Now check knife client list again.
% knife client list tester-validator
Now, we need to get the ceritficate out to every node in the infrastructure in its
trusted_certs_dir – by default this is
/etc/chef/trusted_certs. The most simple way to do this is to use
knife ssh to run knife on the target nodes.
% knife ssh 'name:*' 'sudo knife ssl fetch -c /etc/chef/client.rb' node-output.example.com WARNING: Certificates from chef-server-example.com will be fetched and placed in your trusted_cert node-output.example.com directory (/etc/chef/trusted_certs). node-output.example.com node-output.example.com Knife has no means to verify these are the correct certificates. You should node-output.example.com verify the authenticity of these certificates after downloading. node-output.example.com node-output.example.com Adding certificate for chef-server.example.com in /etc/chef/trusted_certs/chef-server.example.com.crt
The output will be interleaved for all the nodes returned by
knife ssh. Of course, we should verify the SHA256 checksums like before, which can be done again with
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