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pelton extras plugins generate-service-ingresses

A plugin for exposing annotated services to the outside world via HTTP ingresses.

This plugin reads a stream of Kubernetes resources formatted as yaml documents and outputs a modified set of Kubernetes resources as yaml documents. It is thus suitable for use with pelton manifest --plugin.

The input resources are re-output verbatim. In addition, input Service-kind resources annotated with the com.shieldsbetter.pelton/ingress annotation are found and one additional Ingress-kind resources is output for each namespace represented across those services.

Values for the annotation should take the form prefix=>port,prefix=>port. I.e., a comma-delimited list of prefix/port pairs, where prefix and port are separated by the characters =>.

Each output ingress will contain Rules mapping FQDNs derived from the provided domain name prefixes to the requested ports on the associated service.

In the case of services whose source activation is the same as the root activation, each specified port will be exposed at a FQDN formed by combining the requested domain prefix to each suffix specified in the environment variable $PELTON_GSI_DOMAIN_SUFFIX.

In all other cases, each specified port will be exposed by combining the requested domain prefix first with each fragment specified in the environment variable $PELTON_GSI_DEPENDENCY_FRAGMENT and then pairwise with each suffix in $PELTON_GSI_DOMAIN_SUFFIX.

$PELTON_GSI_DOMAIN_SUFFIX's default is .localhost.

$PELTON_GSI_DEPENDENCY_FRAGMENT's default is .${ROOT_PRJ_DNS_NAME_NO_HYPHENS}-${ROOT_ENV}-${ROOT_ISO}, where ROOT_PRJ_DNS_NAME_NO_HYPHENS is the dnsName field of the Pelton project associated with the root activation, ROOT_ENV is the root activation's environment name, and ROOT_ISO is the root activation's isolation name.

Thus, a service annotated with svcA=>123 from the root activation would, by default, have its port 123 exposed as svcA.localhost, while a service annotated with svcB=>124 from a dependency activation spawned by root activation prj-a.default.a would, by default, have its port 124 exposed as svcB.prja-default-a.localhost.

Full Behavior

Environment

The plugin is sensitive to two environment variables:

  • PELTON_GSI_DOMAIN_SUFFIX - a comma-delimeted list of suffixes to be used for each rule. E.g., .localhost,.corp.biz.com. Default: .localhost.
  • PELTON_GSI_DEPENDENCY_FRAGMENT - a comma-delimeted list of partial domain names to be combined pairwise with suffixes in PELTON_GSI_DOMAIN_SUFFIX to form suffixes for services not originating from the root activation. Default: .${ROOT_PRJ_DNS_NAME_NO_HYPHENS}-${ROOT_ENV}-${ROOT_ISO}, where ROOT_PRJ_DNS_NAME_NO_HYPHENS is the dnsName field of the Pelton project associated with the root activation, ROOT_ENV is the root activation's environment name, and ROOT_ISO is the root activation's isolation name.

Annotation

The com.shieldsbetter.pelton/ingress annotation should be set on any service for which rules should be generated.

The value of the annotation should be a string formatted as one or more comma-delimited mappings from a domain prefix to one of the service's ports. Each individual mapping should be formatted as ${DOMAIN_PREFIX}=>${PORT}, that is: a domain prefix, followed by the characters =>, followed by a port number exposed by the service. The domain prefix and arrow may be ommitted, in which case a default domain prefix will be generated.

So, the following are all examples of valid annotation values:

  • foo.plugh=>123
  • foo=>123,bar.waldo=>124
  • 123
  • foo=>123,124

When the domain prefix is omitted, a default will be generated based on the service's metadata.name field. The generated default will be ${SVC_NAME_NO_HYPHENS}-${ENV}-${ISO}, where SVC_NAME_NO_HYPHENS is the name of the service with hyphens removed, ENV is the environment name of the activation associated with the service, and ISO is the isolation name of the activation associated with the service. Thus, for service foo-svc that is part of the foo-prj project that has been activated in activation foo-prj.default-a, the generated default prefix would be foosvc-default-a.

Each mapping will cause the plugin to generate one or more rules on the Ingress in the corresponding namespace.

Generated FQDNs

For each namespace, one Ingress will be generated exposing the services from that namespace.

For each service in a namespace, each mapping will contribute one or more rules to that ingress.

For services whose source activation is the root activation, each mapping will be considered and its domain prefix prepended to each suffix from $PELTON_GSI_DOMAIN_SUFFIX, contributing a number of rules equal to the number of suffixes.

For services whose source activation is not the root activation, each mapping will be considered and its domain prefix prepended first to those domain fragments in $PELTON_GSI_DEPENDENCY_FRAGMENTS and that resulting list combined pairwise with each suffix from $PELTON_GSI_DOMAIN_SUFFIX, contributing a number of rules equal to (n * m) where n is the number of fragments in $PELTON_GSI_DEPENDENCY_FRAGMENTS and m is the number of suffixes in $PELTON_GSI_DOMAIN_SUFFIX.