Merge pull request #108 from UKHomeOffice/add_replace

Add optional replace flag

README.md

@@ -80,6 +80,35 @@ $ kd --context=mykube --namespace=testing --file nginx-deployment.yaml
 
 You can fail an ongoing deployment if there's been a new deployment by adding `--fail-superseded` flag.
 
+### Replace
+
+kd will use the `apply` verb to create / update resources which is [appropriate
+in most cases](https://kubernetes.io/docs/concepts/cluster-administration/manage-deployment/#in-place-updates-of-resources).
+
+The flag `--replace` can be used to override this behaviour can be useful in 
+some very specific scenarios but the result is a [disruptive update](https://kubernetes.io/docs/concepts/cluster-administration/manage-deployment/#disruptive-updates)
+which should not be the default.
+
+To have the desired affect when updating objects, you may need to use optional
+kubectl arguments e.g.: `-- --force` to force deletion of some objects. **NOTE**
+history of an object is lost with `--force`.
+
+**NOTE** `apply` is used internally to create the resource if it doesn't exist.
+
+#### Cronjobs
+
+When a cronjob object is created and only updated, any old jobs will continue
+and some fields are imutable so use of the force option may be required.
+
+E.g. to update a large cron job use `kd --replace -f cronjob.yml -- --force`.
+
+#### Large Objects e.g. Configmaps
+
+As an apply uses 'patch' internally, there is a limit to the size of objects
+that can be updated this way.
+
+E.g. to update a large config map use `kd --replace -f myconfigmap.yml -- --force`.
+
 ### Run command
 
 You can run kubectl with the support of the same flags and environment variables
@@ -261,6 +290,7 @@ GLOBAL OPTIONS:
  --config value Env file location [$CONFIG_FILE, $PLUGIN_CONFIG_FILE]
  --create-only only create resources (do not update, skip if exists). [$CREATE_ONLY, $PLUGIN_CREATE_ONLY]
  --create-only-resource value only create specified resources e.g. 'kind/name' (do not update, skip if exists). [$CREATE_ONLY_RESOURCES, $PLUGIN_CREATE_ONLY_RESOURCES]
+ --replace use replace instead of apply for updating objects [$KUBE_REPLACE, $PLUGIN_KUBE_REPLACE]
  --context CONTEXT, -c CONTEXT kube config CONTEXT [$KUBE_CONTEXT, $PLUGIN_CONTEXT]
  --namespace NAMESPACE, -n NAMESPACE kubernetes NAMESPACE [$KUBE_NAMESPACE, $PLUGIN_KUBE_NAMESPACE]
  --fail-superseded fail deployment if it has been superseded by another deployment. WARNING: there are some bugs in kubernetes. [$FAIL_SUPERSEDED, $PLUGIN_FAIL_SUPERSEDED]

main.go

@@ -39,6 +39,8 @@ const (
  // FlagCaFile is the sytax to specify a CA file when FlagCa specifies a URL or
  // when FlagCaData is set
  FlagCaFile = "certificate-authority-file"
+ // FlagReplace allows the resources to be re-created rather than patched
+ FlagReplace = "replace"
 )
 
 var (
@@ -132,6 +134,11 @@ func main() {
  EnvVar: "CREATE_ONLY_RESOURCES,PLUGIN_CREATE_ONLY_RESOURCES",
  Value: nil,
  },
+ cli.BoolFlag{
+ Name: FlagReplace,
+ Usage: "use replace instead of apply for updating objects",
+ EnvVar: "KUBE_REPLACE,PLUGIN_KUBE_REPLACE",
+ },
  cli.StringFlag{
  Name: "context, c",
  Usage: "kube config `CONTEXT`",
@@ -396,12 +403,16 @@ func splitYamlDocs(data string) []string {
 
 func deploy(c *cli.Context, r *ObjectResource) error {
 
- if r.CreateOnly {
- exists, err := checkResourceExist(c, r)
+ exists := false
+ if r.CreateOnly || c.Bool(FlagReplace) {
+ var err error
+ exists, err = checkResourceExist(c, r)
  if err != nil {
  return fmt.Errorf(
  "problem checking if resource %s/%s exists", r.Kind, r.Name)
  }
+ }
+ if r.CreateOnly {
  if exists {
  log.Printf(
  "skipping deploy for resource (%s/%s) marked as create only.",
@@ -413,6 +424,11 @@ func deploy(c *cli.Context, r *ObjectResource) error {
 
  name := r.Name
  command := "apply"
+ if c.Bool(FlagReplace) {
+ if exists {
+ command = "replace"
+ }
+ }
 
  if r.GenerateName != "" {
  name = r.GenerateName