Reshuffle cloud-config

Read files cloud-config.d in alphanumeric order, then cloud-config.yml
`ros config` writes to cloud-config.yml (and cloud-config.d/private.yml - only private keys)

Add (c *CloudConfig) Save() method, use it to save the changed config

Read and apply metadata as part of LoadConfig()

Simplify ros config export logic

config/metadata_test.go

@@ -0,0 +1,100 @@
+// Copyright 2015 CoreOS, Inc.
+// Copyright 2015 Rancher Labs, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package config
+
+import (
+	"net"
+	"testing"
+
+	"github.com/coreos/coreos-cloudinit/datasource"
+)
+
+func TestSubstituteUserDataVars(t *testing.T) {
+	for _, tt := range []struct {
+		metadata datasource.Metadata
+		input    string
+		out      string
+	}{
+		{
+			// Userdata with docker-compose syntax
+			datasource.Metadata{
+				PublicIPv4:  net.ParseIP("192.0.2.3"),
+				PrivateIPv4: net.ParseIP("192.0.2.203"),
+				PublicIPv6:  net.ParseIP("fe00:1234::"),
+				PrivateIPv6: net.ParseIP("fe00:5678::"),
+			},
+			`servicexyz:
+			  image: rancher/servicexyz:v0.3.1
+			  ports:
+			  - "$public_ipv4:8001:8001"
+			  - "$public_ipv6:8001:8001"
+			  - "$private_ipv4:8001:8001"
+			  - "$private_ipv6:8001:8001"`,
+			`servicexyz:
+			  image: rancher/servicexyz:v0.3.1
+			  ports:
+			  - "192.0.2.3:8001:8001"
+			  - "fe00:1234:::8001:8001"
+			  - "192.0.2.203:8001:8001"
+			  - "fe00:5678:::8001:8001"`,
+		},
+		{
+			// Userdata with cloud-config/rancher syntax
+			datasource.Metadata{
+				PublicIPv4:  net.ParseIP("192.0.2.3"),
+				PrivateIPv4: net.ParseIP("192.0.2.203"),
+				PublicIPv6:  net.ParseIP("fe00:1234::"),
+				PrivateIPv6: net.ParseIP("fe00:5678::"),
+			},
+			`write_files:
+			    - path: /etc/environment
+			      content: |
+			        PRIVATE_IPV6=$private_ipv6
+			        PUBLIC_IPV6=$public_ipv6
+			rancher:
+			  network:
+			    interfaces:
+			      eth1:
+			        address: $private_ipv4/16
+			  docker:
+			  	tls_args: ['-H=$public_ipv4:2376']`,
+			`write_files:
+			    - path: /etc/environment
+			      content: |
+			        PRIVATE_IPV6=fe00:5678::
+			        PUBLIC_IPV6=fe00:1234::
+			rancher:
+			  network:
+			    interfaces:
+			      eth1:
+			        address: 192.0.2.203/16
+			  docker:
+			  	tls_args: ['-H=192.0.2.3:2376']`,
+		},
+		{
+			// no metadata
+			datasource.Metadata{},
+			"address: $private_ipv4",
+			"address: ",
+		},
+	} {
+
+		got := substituteVars([]byte(tt.input), tt.metadata)
+		if string(got) != tt.out {
+			t.Fatalf("Userdata substitution incorrectly applied.\ngot:\n%s\nwant:\n%s", got, tt.out)
+		}
+	}
+}