Certificate System Role - API Design proposal

Linux system role to issue and renew SSL certificates.

Basic usage:

---
- hosts: webserver

  vars:
    certificate_requests:
      - name: mycert
        dns: www.example.com
        ca: self-sign

  roles:
    - certificate

On a RPM-based system this will place the certificate in /etc/pki/tls/certs/mycert.crt and the key in /etc/pki/tls/private/mycert.key.

Variables

Parameter	Description	Type	Required	Default
certificate_wait	If the task should wait for the certificate to be issued.	bool	no	yes
certificate_requests	A list of dicts representing each certificate to be issued. See certificate_requests.	list	no	-

certificate_requests

Note: Fields such as common_name, country, state, locality, organization, organizational_unit, email, key_usage, and extended_key_usage that can be included in the certificate request are defined by the RFC 5280.

Note: Be aware that the CA might not honor all the requested fields. For example, even if a request include country: US, the CA might issue the certificate without country in it's subject.

Note: The fields dns, email and ip are used to define the Subject Alternative Names (SAN).

Parameter	Description	Type	Required	Default
name	Name of the certificate. A full path can be used to choose the directory where files will be stored.	str	yes	-
ca	CA that will issue the certificate. See CAs and Providers.	str	yes	-
dns	Domain (or list of domains) to be included in the certificate. Also can provide the default value for common_name.	str or list	no	-
email	Email (or list of emails) to be included in the certificate.	str or list	no	-
ip	IP, or list of IPs, to be included in the certificate. IPs can be IPv4, IPv6 or both. Also can provide the default value for common_name.	str or list	no	-
auto_renew	Indicates if the certificate should be renewed automatically before it expires.	bool	no	yes
owner	User name (or user id) for the certificate and key files.	str	no	User running Ansible
group	Group name (or group id) for the certificate and key files.	str	no	Group running Ansible
key_size	Generate keys with a specific keysize in bits.	int	no	2048 - See key_size
common_name	Common Name requested for the certificate subject.	str	no	See common_name
country	Country requested for the certificate subject.	str	no	-
state	State requested for the certificate subject.	str	no	-
locality	Locality requested for the certificate subject (usually city).	str	no	-
organization	Organization requested for the certificate subject.	str	no	-
organizational_unit	Organizational unit requested for the certificate subject.	str	no	-
contact_email	Contact email requested for the certificate subject.	str	no	-
key_usage	Allowed Key Usage for the certificate. For valid values see: key_usage.	list	no	See key_usage
extended_key_usage	Extended Key Usage attributes to be present in the certificate request.	list	no	See extended_key_usage
run_before	Command that should run before saving the certificate. See run hooks.	str	no	-
run_after	Command that should run after saving the certificate. See run hooks.	str	no	-
principal	Kerberos principal.	str	no	-
provider	The underlying method used to request and manage the certificate.	str	no	Varies by CA

common_name

If common_name is not set the role will attempt to use the first value of dns or ip, respectively, as the default. If dns and ip are also not set, common_name will not be included in the certificate.

key_size

Recommended minimal-values for a certificate key size, from different organizations, vary across time. In the attempt to provide safe settings, the default minimal-value for key_size will be increased over time.

If you want your certificates to always keep the same key_size when renewed, set this variable to the desired value.

key_usage

Valid values for key_usage are:

• digitalSignature
• nonRepudiation
• keyEncipherment
• dataEncipherment
• keyAgreement
• keyCertSign
• cRLSign
• encipherOnly
• decipherOnly

The defaults for key_usage are:

• digitalSignature
• keyEncipherment

extended_key_usage

Any valid oid can be used to set one or more extended_key_usage. In addition to that there is also a list of known aliases that will be recognized by the role:

• id-kp-serverAuth
• id-kp-clientAuth
• id-kp-codeSigning
• id-kp-emailProtection
• id-kp-timeStamping
• id-kp-OCSPSigning
• id-kp-ipsecEndSystem
• id-kp-ipsecTunnel
• id-kp-ipsecUser

If extended_key_usage is not set the role will default to:

• id-kp-serverAuth
• id-kp-clientAuth

run hooks

Sometimes you need to execute a command just before a certificate is renewed and another command just after. In order to do that use run_before and run_after.

The value provided to run_before and run_after will be wrapped and stored in shell script files that later will be executed by the provider.

CAs and Providers

CA	Providers	CA description	Requirements
self‑sign	certmonger*	Issue self-signed certificates from a local CA.
ipa	certmonger*	Issue certificates using the FreeIPA CA.	Host needs to be enrolled in a FreeIPA server.

* Default provider.

CA represents the CA certificates that will be used to issue and sign the requested certificate. Provider it's the method used to send the certificate request to the CA and then retrieve the signed certificate.

If a user chooses self-sign CA, with certmonger as provider and, later on decide to change the provider to openssl, the CA certificates used in both cases needs to be the same. Please note that openssl is not yet a supported provider and it's only mentioned here as an example.

Facts

This role provides facts that can be useful for conditional control in playbooks or even for debugging.

certificate_available_cas

A list of available CAs in the host.

If any CA is listed in CAs and Providers but it's not showing in the certificate_available_cas fact, it means that this CA doesn't meet the requirements to be enabled.

For example if host is not enrolled in an IPA server:

{
    "certificate_available_cas": [
        "self-sign"
    ]
}

If host is enrolled in an IPA server:

{
    "certificate_available_cas": [
        "self-sign",
        "ipa"
    ]
}

Examples:

Issue a self-signed certificate:

Issue a certificate for *.example.com and place it in the standard directory for the distribution.

---
- hosts: webserver

  vars:
    certificate_requests:
      - name: mycert
        dns: *.example.com
        ca: self-sign

  roles:
    - certificate

The directories for each distribution are:

• Debian/Ubuntu:

  • Certificates: /etc/ssl/localcerts/certs/
  • Keys: /etc/ssl/localcerts/private/

• RHEL/CentOS/Fedora:

  • Certificates: /etc/pki/tls/certs/
  • Keys: /etc/pki/tls/private/

Choose where the certificates will be placed

Issue a certificate and key and place them in the specified location. The example bellow will create a certificate file in /another/path/mycert.crt and a key file in /another/path/mycert.key.

---
- hosts: webserver
  vars:
    certificate_requests:
      - name: /another/path/mycert
        dns: *.example.com
        ca: self-sign

  roles:
    - certificate

Certificates with multiple DNS, IP and Email

---
- hosts: webserver
  vars:
    certificate_requests:
      - name: mycert
        dns:
          - www.example.com
          - sub1.example.com
          - sub2.example.com
          - sub3.example.com
        ip:
          - 192.0.2.12
          - 198.51.100.65
          - 2001:db8::2:1
        email:
          - sysadmin@example.com
          - support@example.com
        ca: self-sign

  roles:
    - certificate

Setting common subject options

---
- hosts: webserver
  vars:
    certificate_requests:
      - name: mycert
        dns: www.example.com
        common_name: www.example.com
        ca: self-sign
        country: US
        state: NY
        locality: New York
        organization: Red Hat
        organizational_unit: platform
        email: admin@example.com
  roles:
    - certificate

Setting the certificate key size

---
- hosts: webserver
  vars:
    certificate_requests:
      - name: mycert
        dns: www.example.com
        ca: self-sign
        key_size: 4096
  roles:
    - certificate

Setting the "Key Usage" and "Extended Key Usage" (EKU)

---
- hosts: webserver
  vars:
    certificate_requests:
      - name: mycert
        dns: www.example.com
        ca: self-sign
        key_usage:
          - digitalSignature
          - nonRepudiation
          - keyEncipherment
        extended_key_usage:
          - id-kp-clientAuth
          - id-kp-serverAuth
  roles:
    - certificate

Don't wait for the certificate to be issued

The certificate issuance can take several minutes depending on the CA. Because of that it's also possible to request the certificate but not actually wait for it.

---
- hosts: webserver
  vars:
    certificate_wait: false
    certificate_requests:
      - name: mycert
        dns: www.example.com
        ca: self-sign
  roles:
    - certificate

Set a principal

---
- hosts: webserver
  vars:
    certificate_requests:
      - name: mycert
        dns: www.example.com
        ca: self-sign
        principal: HTTP/www.example.com

  roles:
    - certificate

Choosing to not auto-renew a certificate

By default certificates generated by the role will be set for auto-renewal. To disable that behavior set auto_renew: no.

---
- hosts: webserver
  vars:
    certificate_requests:
      - name: mycert
        dns: www.example.com
        ca: self-sign
        auto_renew: no

  roles:
    - certificate

Using FreeIPA to issue a certificate

If your host is enrolled in a FreeIPA server you will also have the option to use it's CA to issue your certificate. To do that just set ca: ipa.

---
- hosts: webserver
  vars:
    certificate_requests:
      - name: mycert
        dns: www.example.com
        ca: ipa

  roles:
    - certificate

In case you want to use FreeIPA but fallback to self-sign if the host is not enrolled:

- hosts: webserver
  vars:
    certificate_requests:
      - name: mycert
        dns: www.example.com
        ca: "{{ 'ipa' if 'ipa' in certificate_available_cas else 'self-sign' }}"
  roles:
    - certificate

Running a command before or after a certificate is issued

Sometimes you need to execute a command just before a certificate is renewed and another command just after. In order to do that use run_before and run_after.

---
- hosts: webserver
  vars:
    certificate_requests:
      - name: mycert
        dns: www.example.com
        ca: self-sign
        run_before: systemctl stop webserver.service
        run_after: systemctl start webserver.service

  roles:
    - certificate

Setting the certificate owner and group

If you are using a certificate for a service, for example httpd, it's likely that you'll need to set the certificate owner and group that will own the certificate. In the following example the owner and group are both set to httpd.

---
- hosts: webserver
  vars:
    certificate_requests:
      - name: mycert
        dns: www.example.com
        ca: self-sign
        owner: httpd
        group: httpd

  roles:
    - certificate

Please note that it's also possible to use UID and GID instead of user and group names.