Kubernetes supports annotations on any kubernetes resource such as on a replication controller or service which are a great way to add arbitrary metadata. Note that annotation are limited in total to about 64Kb so any large metadata should be added via a URL rather than in place.
These annotations are to help support Continuous Delivery and to link deployments to the CI build which generated the image along with the source code changes and so forth.
| Annotation | Description | Example |
|---|---|---|
| fabric8.io/build-id | The build number used to generate this docker image and kubernetes resource | 2 |
| fabric8.io/build-url | The URL to view the build which generated the docker image and kubernetes resource | http://jenkins.vagrant.f8/job/gogsadmin-james3/2 |
| fabric8.io/git-branch | The git branch that generated the image | gogsadmin-james3-1.0.2 |
| fabric8.io/git-commit | The git commit ID of the source code used to generate the image | 5e1116f63df0bac2a80bdae2ebdc563577bbdf3c |
| fabric8.io/git-url | The URL to view the git commit history | http://gogs.vagrant.f8/gogsadmin/james3/commit/5e1116f63df0bac2a80bdae2ebdc563577bbdf3c |
For more background on these annotation see the Secret Annotations document; they are used to annotate OpenShift templates and replication controllers with their secret requirements so that its easier to install applications using gofabric8 and the gofabric8 secrets command:
| Annotation | Description | Example |
|---|---|---|
| fabric8.io/secret-ssh-key | Defines one or more named ssh keys (public and private key pairs) | mysecretname or secret1,secret2,anothersecret |
| fabric8.io/secret-ssh-public-key | Refers to a single or a bag of public keys | mysecretname.pub or mybagofsecrets[cheese.pub,beer.pub] |
| fabric8.io/secret-gpg-key | Refers to a GPG key | mysecretname |
When using Prometheus to collect metrics for monitoring your containers you may wish to add these annotations to the service:
| Annotation | Description | Example |
|---|---|---|
| prometheus.io/scrape | Enable/disable the export of metrics to Prometheus | true |
| prometheus.io/path | the request path to find metrics to export to Prometheus | /metrics |
| prometheus.io/port | the request port to find metrics to export to Prometheus | 8080 |