Add hub stats function

sample-functions/DockerHubStats/.gitignore

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+DockerHubStats

sample-functions/DockerHubStats/Dockerfile

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+FROM golang:1.7.3-alpine
+MAINTAINER alexellis2@gmail.com
+ENTRYPOINT []
+
+RUN apk --no-cache add make
+WORKDIR /go/src/github.com/alexellis/faas/sample-functions/DockerHubStats
+COPY . /go/src/github.com/alexellis/faas/sample-functions/DockerHubStats
+
+RUN make
+COPY fwatchdog /usr/bin/fwatchdog
+ENV fprocess "/go/bin/DockerHubStats"
+
+CMD [ "/usr/bin/fwatchdog"]

sample-functions/DockerHubStats/Makefile

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+
+.PHONY: install image
+
+install:
+	@go install .
+
+image:
+	@docker build -t alexellis2/dockerhub-stats .
+

sample-functions/DockerHubStats/README.md

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+Building:
+
+```
+# docker service rm hubstats ; docker service create --network=functions --name=hubstats alexellis2/dockerhub-stats
+```
+
+Query the function through the gateway:
+
+```
+# curl -X POST -d "alexellis2" -v http://localhost:8080/function/hubstats
+```

sample-functions/DockerHubStats/main.go

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+package main
+
+import (
+	"encoding/json"
+	"fmt"
+	"io/ioutil"
+	"log"
+	"net/http"
+	"os"
+	"strings"
+)
+
+type dockerHubStatsType struct {
+	Count int `json:"count"`
+}
+
+func sanitizeInput(input string) string {
+	parts := strings.Split(input, "\n")
+	return strings.Trim(parts[0], " ")
+}
+
+func requestHubStats(org string) dockerHubStatsType {
+	client := http.Client{}
+	res, err := client.Get("https://hub.docker.com/v2/repositories/" + org)
+	if err != nil {
+		log.Fatalln("Unable to reach Docker Hub server.")
+	}
+
+	body, err := ioutil.ReadAll(res.Body)
+	if err != nil {
+		log.Fatalln("Unable to parse response from server.")
+	}
+
+	dockerHubStats := dockerHubStatsType{}
+	json.Unmarshal(body, &dockerHubStats)
+	return dockerHubStats
+}
+
+func main() {
+	input, err := ioutil.ReadAll(os.Stdin)
+	if err != nil {
+		log.Fatal("Unable to read standard input:", err)
+	}
+	org := string(input)
+	if len(input) == 0 {
+		log.Fatalln("A username or organisation is required.")
+	}
+
+	org = sanitizeInput(org)
+	dockerHubStats := requestHubStats(org)
+
+	fmt.Printf("The organisation or user %s has %d repositories on the Docker hub.\n", org, dockerHubStats.Count)
+}