google-ssl-cert

Google Ssl Cert Rotation Tool

A Google SSL Cert rotation automation tool.

How Does It Work?

You should run this tool in the folder with your cert files. The cert files can be inferred conventionally or explicitly specified. Tool can be used in conjuction with Kubes and the google_secret helper. It can be used to automate the SSL cert rotation process.

This is done by generating a new SSL cert and storing that name to Google secrets. All the user needs to do is be in the folder with the cert private key and signed cert. These files are typically named: private.key and certificate.crt. The key is that the Google Secret name itself does not change, only it's value.

Kubes Kuberbetes YAML

Your Kuberbetes YAML files can be built with Kubes with the google_secret helper which references the cert name.

Example ingress.yaml with an L7 external load balancer and global cert.

.kubes/resources/web/ingress.yaml:

apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: web
  annotations:
    ingress.gcp.kubernetes.io/pre-shared-cert: '<%= google_secret("cert-app1", base64: false) %>'
spec:
  defaultBackend:
    service:
      name: web
      port:
        number: 80

The .kubes/resources/web/ingress.yaml code remains the same, but the generated/compiled .kubes/output/web/ingress.yaml will have the new Google SSL Cert name. This triggers Kuberbetes to do a rolling deploy properly.

Summary of Steps

1. Use the google-ssl-cert create command to create new SSL cert and save the name to Google Secrets. The value in the Google Secret can be later referenced.
2. Deploying your application to Kuberbetes and using the Kubes google_secret helper that references the new cert name.
3. Pruning the old cert names with the google-ssl-cert prune command.

Usage: Quick Start

Make sure you have the cert files in your current folder:

$ ls
private.key  certificate.crt

Command synopsys:

google-ssl-cert create CERT_NAME

Note: Google ssl cert names can only contain letters, numbers, and dashes. Underscores are not allowed.

Example:

$ google-ssl-cert create cert-app1
Global cert created: cert-app1-global-20211021155725
Secret saved: name: cert-app1 value: cert-app1-global-20211021155725

The secret conventionally is the same as the cert name. You can override it with --secret-name.

Check that cert and secret was created on google cloud:

% gcloud compute ssl-certificates list
NAME                             TYPE          CREATION_TIMESTAMP             EXPIRE_TIME                    MANAGED_STATUS
cert-app1-global-20211021155725  SELF_MANAGED  2021-10-21T08:57:26.005-07:00  2022-01-12T15:59:59.000-08:00
~/environment/cert-files git:master aws:tung:us-west-2 gke:default
%
$ gcloud secrets versions access latest --secret cert-app1
cert-app1-global-20211021155725

Usage: Region Cert

If you need to create a region cert instead, IE: for internal load balancers, specify the --no-global flag. Example:

$ google-ssl-cert create cert-app1 --no-global
Region cert created: cert-app1-us-central1-20211021155852 in region: us-central1
Secret saved: name: cert-app1 value: cert-app1-us-central1-20211021155852

Check that cert and secret was created on google cloud:

$ gcloud compute ssl-certificates list
NAME                                  TYPE          CREATION_TIMESTAMP             EXPIRE_TIME                    MANAGED_STATUS
cert-app1-us-central1-20211021155852  SELF_MANAGED  2021-10-21T08:58:53.514-07:00  2022-01-12T15:59:59.000-08:00

Required Env Vars

These env vars should be set:

Name	Description
GOOGLE_APPLICATION_CREDENTIALS	A service account as must be set up. GOOGLE_APPLICATION_CREDENTIALS is set to the path of the file. IE: export GOOGLE_APPLICATION_CREDENTIALS=~/.gcp/credentials.json
GOOGLE_PROJECT	The env var GOOGLE_PROJECT and must be set.
GOOGLE_REGION	The env var GOOGLE_REGION and must be set when creating a region-based google ssl cert. So when using the --no-global flag

To check that GOOGLE_APPLICATION_CREDENTIALS is valid and is working you can use the boltops-tools/google_check test script to check. Here are the summarized commands:

git clone https://github.com/boltops-tools/google_check
cd google_check
bundle
bundle exec ruby google_check.rb

Cert Files Conventions

The tool will look in your current folder for these private keys in the following order:

private.key
server.key
key.pem

And look for these certs:

certificate.crt
server.crt
cert.pem

So, for example, if you name your cert files in your current folder conventionally like so:

private.key     # private key
certificate.crt # signed cert

The tool is able to detect it and automatically use those files to create the cert.

You can also specify the path to the certificate and private key explicitly:

google-ssl-cert create cert-app1 --private-key server.key --certificate server.crt

Prune

To prune or delete old google ssl certs after rotating:

google-ssl-cert prune CERT_NAME

Installation

gem install google-ssl-cert

Contributing

1. Fork it
2. Create your feature branch (git checkout -b my-new-feature)
3. Commit your changes (git commit -am "Add some feature")
4. Push to the branch (git push origin my-new-feature)
5. Create new Pull Request