Merge pull request kelseyhightower#333 from jnummelin/feature/ip_dns_…

…resolving

IP dns resolving function for templates

.dockerignore

@@ -0,0 +1,3 @@
+bin
+vendor
+pkg

Dockerfile.build.alpine

@@ -0,0 +1,9 @@
+FROM gliderlabs/alpine:3.2
+MAINTAINER Jussi Nummelin <[email protected]>
+RUN apk-install bash go bzr git mercurial subversion openssh-client ca-certificates
+
+RUN mkdir -p /go/src /go/bin && chmod -R 777 /go
+ENV GOPATH /go
+ENV PATH /go/bin:$PATH
+WORKDIR /app
+RUN go get github.com/constabulary/gb/...

docs/installation.md

@@ -23,6 +23,16 @@ $ ./build
 $ sudo ./install
 ```
 
+#### Building from Source for Alpine Linux
+
+Since many people are using Alpine Linux as their base images for Docker there's support to build Alpine package also. Naturally by using Docker itself. :)
+
+```
+$ docker build -t confd_builder -f Dockerfile.build.alpine .
+$ docker run -ti -v $(pwd):/app confd_builder ./build
+```
+The above docker commands will produce binary in the local bin directory.
+
 ### Next Steps
 
 Get up and running with the [Quick Start Guide](quick-start-guide.md).

docs/templates.md

@@ -239,6 +239,16 @@ Alias for the strings.Join function.
 services: {{join $services ","}}
 ```
 
+### lookupIP
+
+Wrapper for net.LookupIP function. The wrapper also sorts (alphabeticaly) the IP addresses. This is crucial since in dynamic environments DNS servers typically shuffle the addresses linked to domain name. And that would cause unnecessary config reloads.
+
+```
+{{range lookupIP "some.host.local"}}
+    server {{.}};
+{{end}}
+```
+
 ## Example Usage
 
 ```Bash
@@ -380,4 +390,3 @@ server {
 ```
 
 Go's [`text/template`](http://golang.org/pkg/text/template/) package is very powerful. For more details on it's capabilities see its [documentation.](http://golang.org/pkg/text/template/)
-

src/github.com/kelseyhightower/confd/resource/template/template_funcs.go

@@ -6,6 +6,8 @@ import (
 	"path"
 	"strings"
 	"time"
+	"net"
+	"sort"
 )
 
 func newFuncMap() map[string]interface{} {
@@ -22,6 +24,7 @@ func newFuncMap() map[string]interface{} {
 	m["toLower"] = strings.ToLower
 	m["contains"] = strings.Contains
 	m["replace"] = strings.Replace
+	m["lookupIP"] = LookupIP
 	return m
 }
 
@@ -42,3 +45,18 @@ func UnmarshalJsonArray(data string) ([]interface{}, error) {
 	err := json.Unmarshal([]byte(data), &ret)
 	return ret, err
 }
+
+func LookupIP(data string) ([]string) {
+	ips, err := net.LookupIP(data)
+	if(err != nil) {
+		return nil
+	}
+	// "Cast" IPs into strings and sort the array
+	ipStrings := make([]string, len(ips))
+
+	for i, ip := range ips {
+		ipStrings[i] = ip.String()
+	}
+	sort.Strings(ipStrings)
+	return ipStrings
+}

src/github.com/kelseyhightower/confd/resource/template/template_test.go

@@ -363,6 +363,34 @@ dir: {{.}}
 
 dir: /test/data
 
+`,
+		updateStore: func(tr *TemplateResource) {
+			tr.store.Set("/test/data", "parent")
+			tr.store.Set("/test/data/def", "child")
+		},
+	},
+	templateTest{
+		desc: "ip lookup test",
+		toml: `
+[template]
+src = "test.conf.tmpl"
+dest = "./tmp/test.conf"
+keys = [
+    "/test/data",
+    "/test/data/abc",
+]
+`,
+		tmpl: `
+{{range lookupIP "localhost"}}
+ip: {{.}}
+{{end}}
+`,
+		expected: `
+
+ip: 127.0.0.1
+
+ip: ::1
+
 `,
 		updateStore: func(tr *TemplateResource) {
 			tr.store.Set("/test/data", "parent")