Inject stack name into userdata for nodepool workers (#735)

Fixes #727

Author: redbaron

core/controlplane/config/templates/cloud-config-worker

@@ -1,6 +1,5 @@
-{{ define "instance" -}}
+{{ define "instance-script" -}}
 {{- $S3URI := self.Parts.s3.Asset.S3URL -}}
-#!/bin/bash -xe
  . /etc/environment
 export COREOS_PRIVATE_IPV4 COREOS_PRIVATE_IPV6 COREOS_PUBLIC_IPV4 COREOS_PUBLIC_IPV6
 REGION=$(curl -s http://169.254.169.254/latest/dynamic/instance-identity/document | jq -r '.region')
@@ -22,14 +21,17 @@ run aws s3 --region $REGION  cp {{ $S3URI }} /var/run/coreos/$USERDATA_FILE
 
 INSTANCE_ID=$(curl -s http://169.254.169.254/latest/meta-data/instance-id)
 
-run /bin/sh -c 'echo {{.StackNameEnvVarName}}=$(aws ec2 describe-tags --region "'$REGION'" --filters \
-  "Name=resource-id,Values='$INSTANCE_ID'" \
-  "Name=key,Values=aws:cloudformation:stack-name" \
-  --output json \
-| jq -r ".Tags[].Value") >> {{.StackNameEnvFileName}}'
-
 exec /usr/bin/coreos-cloudinit --from-file /var/run/coreos/$USERDATA_FILE
 {{ end }}
+
+{{ define "instance" -}}
+{ "Fn::Base64": { "Fn::Join" : ["", [
+  "#!/bin/bash -xe\n",
+  {"Fn::Join":["",[ "echo '{{.StackNameEnvVarName}}=", { "Ref": "AWS::StackName" }, "' >> {{.StackNameEnvFileName}}\n" ]]},
+  {{ (execTemplate "instance-script" .) | toJSON  }}
+]]}}
+{{ end }}
+
 {{ define "s3" -}}
 #cloud-config
 coreos:

core/nodepool/config/templates/stack-template.json

@@ -101,7 +101,7 @@
               {{end}}
             ],
             "SubnetId": {{$workerSubnet.Ref}},
-            "UserData": {{ $.UserDataWorker.Parts.instance.Base64 true | checkSizeLessThan 16384 | quote }}
+            "UserData": {{ $.UserDataWorker.Parts.instance.Template }}
           }
           {{end}}
           {{end}}
@@ -261,7 +261,7 @@
         {{else}}
         "PlacementTenancy": "{{.Tenancy}}",
         {{end}}
-        "UserData": {{ .UserDataWorker.Parts.instance.Base64 true | checkSizeLessThan 16384 | quote }}
+        "UserData": {{ .UserDataWorker.Parts.instance.Template }}
       },
       "Type": "AWS::AutoScaling::LaunchConfiguration"
     {{if not .IAMConfig.InstanceProfile.Arn}}

filereader/texttemplate/texttemplate.go

@@ -2,6 +2,7 @@ package texttemplate
 
 import (
 	"bytes"
+	"encoding/json"
 	"fmt"
 	"github.com/Masterminds/sprig"
 	"io/ioutil"
@@ -21,9 +22,27 @@ func Parse(filename string, funcs template.FuncMap) (*template.Template, error)
 			}
 			return content, nil
 		},
+		"toJSON": func(v interface{}) (string, error) {
+			data, err := json.Marshal(v)
+			return string(data), err
+		},
+		"execTemplate": func(name string, ctx interface{}) (string, error) {
+			panic("[bug] Stub 'execTemplate' was not replaced")
+		},
+	}
+
+	t, err := template.New(filename).Funcs(sprig.HermeticTxtFuncMap()).Funcs(funcs).Funcs(funcs2).Parse(string(raw))
+	if err == nil {
+		t = t.Funcs(template.FuncMap{
+			"execTemplate": func(name string, ctx interface{}) (string, error) {
+				b := bytes.Buffer{}
+				err := t.ExecuteTemplate(&b, name, ctx)
+				return b.String(), err
+			},
+		})
 	}
+	return t, err
 
-	return template.New(filename).Funcs(sprig.HermeticTxtFuncMap()).Funcs(funcs).Funcs(funcs2).Parse(string(raw))
 }
 
 func GetBytesBuffer(filename string, data interface{}) (*bytes.Buffer, error) {