Replace custom rollout timeout implementation with kubectl native alternative

[montmanu]

Description

Currently, support for the wait_deployments and wait_seconds parameters of drone-gke is implemented in part by a separate utility – a musl variant of timeout(1). This command is used in combination with the kubectl rollout status subcommand to ensure that rollout(s) of specific resource(s) succeed within a specific duration.

I'm not sure when support for the --timeout argument was added to kubectl rollout status, but I believe it can now be used to achieve the objective as the current implementation.

Desired Outcome

kubectl and drone-gke should both continue to function as expected when replacing the timeout command based implementation with the --timeout argument based implementation. In other words, both drone-gke and kubectl rollout status should continue to exit with a non-zero code if a rollout fails to complete within the specified duration; otherwise, each program should continue exiting with a 0 code.

The following is a psuedo-code example intended to demonstrate the core of a potential kubectl native alternative for the rollout duration threshold condition:

##
# $PLUGIN_WAIT_DEPLOYMENTS - a list of user specified resources which may have associated rollouts pending
# due to a previous `kubectl apply` execution (example: deployment/nginx)
##

##
# $PLUGIN_WAIT_SECONDS - a user specified rollout duration threshold (example: 180)
# any pending rollouts that are associated with the above resources must complete
# successfully within this duration; otherwise, the rollout is considered to have failed
# and the drone-gke process must exit with a non-zero status code
##

for resource in "${PLUGIN_WAIT_DEPLOYMENTS[@]}"; do
  ##
  # watch the rollout status of the latest revision associated with current $resource,
  # and wait until one of the following conditions is met:
  #
  # - the rollout has completed
  # - the duration represented by the --timeout argument has been exceeded
  ##
  kubectl rollout status "${resource}" --timeout "${PLUGIN_WAIT_SECONDS}s"

  ##
  # here, `$?` will be set to 0 if the rollout completed successfully within the specified duration.
  # otherwise `$?` will be set to a non-zero value.
  #
  # if during any iteration `kubectl rollout status` results in a non-zero exit code,
  # the `drone-gke` process must also exit with a non-zero code.
  ##
done

Alternatives Considered

None.

Related Resources

kubectl help rollout status

https://kubernetes.io/docs/reference/generated/kubectl/kubectl-commands#-em-status-em-

#26

#58

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#121