Updating the CA Certificate bundle in Chef Installations
Installations of the Chef Development Kit and the Chef Workstation include their own bundle of Certificate Authority Certificates. As these are tied to the installation of Chef, an upgrade generally means that you'd need to update Chef.
This may not always be possible - in a lot of environments, you'll be using a private certificate authority for internal-only applications, which means as much as you update Chef, it'll never trust your internal services. Alternatively, you may be stuck on an older version of Chef, and unable/unwilling to upgrade to a newer version, so need a way of updating/augmenting the certs.
For instance, let's say that we're on a very old version of Chef (from ~2018):
$ chef --version
Chef Development Kit Version: 3.5.13
chef-client version: 14.7.17
delivery version: master (6862f27aba89109a9630f0b6c6798efec56b4efe)
berks version: 7.0.6
kitchen version: 1.23.2inspec version: 3.0.52
Due to the Let's Encrypt root certificate expiry, a number of domains in 2022 will no longer be trusted by this version of Chef, as the CA Certs don't include the new root certificate.
This means that if we were to try and interact with a certificate that has a root cert from the new Let's Encrypt cert, we'd see a certificate error:
$ curl --cacert /opt/chefdk/embedded/ssl/cert.pem https://www-api.jvt.me -I
curl: (60) SSL certificate problem: certificate has expired
More details here: https://curl.haxx.se/docs/sslcerts.html
curl failed to verify the legitimacy of the server and therefore could not
establish a secure connection to it. To learn more about this situation and
how to fix it, please visit the web page mentioned above.
This is also true for internal CA certs, in the case you're running your own Public Key Infrastructure (PKI).
So how do we update it? If we look at /opt/chefdk/embedded/ssl/cert.pem on the ChefDK, or /opt/chef-workstation/embedded/ssl/cert.pem on the Chef Workstation, we can see the format of the file:
##
## Bundle of CA Root Certificates
##
## Certificate data from Mozilla as of: Wed Oct 17 03:12:10 2018 GMT
##
## This is a bundle of X.509 certificates of public Certificate Authorities
## (CA). These were automatically extracted from Mozilla's root certificates
## file (certdata.txt). This file can be found in the mozilla source tree:
## https://hg.mozilla.org/releases/mozilla-release/raw-file/default/security/nss/lib/ckfw/builtins/certdata.txt
##
## It contains the certificates in PEM format and therefore
## can be directly used with curl / libcurl / php_curl, or with
## an Apache+mod_ssl webserver for SSL client authentication.
## Just configure this file as the SSLCACertificateFile.
##
## Conversion done with mk-ca-bundle.pl version 1.27.
## SHA256: 3f875d87fee4ce3d966c69f1d6c111aa95c0143ade59e4fa24882c582bb5f0ca
##
GlobalSign Root CA
==================
-----BEGIN CERTIFICATE-----
MIIDdTCCAl2gAwIBAgILBAAAAAABFUtaw5QwDQYJKoZIhvcNAQEFBQAwVzELMAkGA1UEBhMCQkUx
GTAXBgNVBAoTEEdsb2JhbFNpZ24gbnYtc2ExEDAOBgNVBAsTB1Jvb3QgQ0ExGzAZBgNVBAMTEkds
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-----END CERTIFICATE-----
GlobalSign Root CA - R2
=======================
-----BEGIN CERTIFICATE-----
...
Fortunately, this file is a bundle of the certificates, which can have a title for human readable means, but contains the root CA's certificate.
Adding a single certificate
So, if we wanted to get our very old ChefDK working, we'd locate the root certificate for Let's Encrypt, and simply append it to the end of the file:
...
-----END CERTIFICATE-----
ISRG Root X1
============
-----BEGIN CERTIFICATE-----
MIIFazCCA1OgAwIBAgIRAIIQz7DSQONZRGPgu2OCiwAwDQYJKoZIhvcNAQELBQAwTzELMAkGA1UE
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m+kXQ99b21/+jh5Xos1AnX5iItreGCc=
-----END CERTIFICATE-----
In this specific case of the Let's Encrypt, we'd also need to remove the other CA certs that have expired, and once we do, HTTPS calls succeed!
Updating the whole CA Cert bundle
Alternatively, you may want to completely modernise the CA Cert bundle, making sure it's updated to a newer version.
As noted in the cert bundle, we're using the bundle from Mozilla, which can either be extracted yourself, or using the pre-extracted bundle that curl provides.
