title: How to diagnose certificate secret not being generated cert-manager?
body: <p>I have created a <code>Certifate</code> and a <code>ClusterIssuer</code>.</p>
  
  <p>I see the following in the cert-manager pod :</p>
  
  <pre><code>I1205 10:43:33.398387       1 setup.go:73] letsencrypt: generating acme account private key "letsencrypt-key"
  I1205 10:43:33.797808       1 logger.go:88] Calling GetAccount
  I1205 10:43:34.622715       1 logger.go:83] Calling CreateAccount
  I1205 10:43:34.826902       1 setup.go:181] letsencrypt: verified existing registration with ACME server
  I1205 10:43:34.826932       1 helpers.go:147] Setting lastTransitionTime for ClusterIssuer "letsencrypt" condition "Ready" to 2018-12-05 10:43:34.826925858 +0000 UTC m=+8919.950996321
  I1205 10:43:34.833364       1 controller.go:154] clusterissuers controller: Finished processing work item "letsencrypt"
  I1205 10:43:43.797372       1 controller.go:140] clusterissuers controller: syncing item 'letsencrypt'
  I1205 10:43:43.797637       1 setup.go:144] Skipping re-verifying ACME account as cached registration details look sufficient.
  I1205 10:43:43.797667       1 controller.go:154] clusterissuers controller: Finished processing work item "letsencrypt"
  I1205 11:07:17.492578       1 controller.go:140] clusterissuers controller: syncing item 'letsencrypt'
  I1205 11:07:17.493076       1 setup.go:144] Skipping re-verifying ACME account as cached registration details look sufficient.
  I1205 11:07:17.493107       1 controller.go:154] clusterissuers controller: Finished processing work item "letsencrypt"
  I1205 11:49:10.390864       1 controller.go:171] certificates controller: syncing item 'staging/acme-crt'
  I1205 11:49:10.391909       1 helpers.go:194] Setting lastTransitionTime for Certificate "acme-crt" condition "Ready" to 2018-12-05 11:49:10.391887695 +0000 UTC m=+12855.515958147
  I1205 11:49:10.399460       1 controller.go:185] certificates controller: Finished processing work item "staging/acme-crt"
  I1205 11:49:12.400064       1 controller.go:171] certificates controller: syncing item 'staging/acme-crt'
  I1205 11:49:12.400270       1 controller.go:185] certificates controller: Finished processing work item "staging/acme-crt"
  </code></pre>
  
  <p>There is no 'certificate' being generated - I assume this because the secret referenced in my <code>Certficate</code> resource is not generated.</p>
  
  <p>How can I diagnose this further?</p>