Support subpaths for http datasources (#442)

* bug: subpaths were ignored in http datasources

Signed-off-by: Dave Henderson <dhenderson@gmail.com>

* fixup! bug: subpaths were ignored in http datasources

1 files changed, 100 insertions, 0 deletions

diff --git a/data/datasource_http.go b/data/datasource_http.go
new file mode 100644
index 00000000..5424fbd0
--- /dev/null
+++ b/data/datasource_http.go
@@ -0,0 +1,100 @@
+package data
+
+import (
+	"io/ioutil"
+	"mime"
+	"net/http"
+	"net/url"
+	"strings"
+	"time"
+
+	"github.com/pkg/errors"
+)
+
+func buildURL(base *url.URL, args ...string) (*url.URL, error) {
+	if len(args) == 0 {
+		return base, nil
+	}
+	p, err := url.Parse(args[0])
+	if err != nil {
+		return nil, errors.Wrapf(err, "bad sub-path %s", args[0])
+	}
+	return base.ResolveReference(p), nil
+}
+
+func readHTTP(source *Source, args ...string) ([]byte, error) {
+	if source.hc == nil {
+		source.hc = &http.Client{Timeout: time.Second * 5}
+	}
+	u, err := buildURL(source.URL, args...)
+	if err != nil {
+		return nil, err
+	}
+	req, err := http.NewRequest("GET", u.String(), nil)
+	if err != nil {
+		return nil, err
+	}
+	req.Header = source.header
+	res, err := source.hc.Do(req)
+	if err != nil {
+		return nil, err
+	}
+	body, err := ioutil.ReadAll(res.Body)
+	if err != nil {
+		return nil, err
+	}
+	err = res.Body.Close()
+	if err != nil {
+		return nil, err
+	}
+	if res.StatusCode != 200 {
+		err := errors.Errorf("Unexpected HTTP status %d on GET from %s: %s", res.StatusCode, source.URL, string(body))
+		return nil, err
+	}
+	ctypeHdr := res.Header.Get("Content-Type")
+	if ctypeHdr != "" {
+		mediatype, _, e := mime.ParseMediaType(ctypeHdr)
+		if e != nil {
+			return nil, e
+		}
+		source.mediaType = mediatype
+	}
+	return body, nil
+}
+
+func parseHeaderArgs(headerArgs []string) (map[string]http.Header, error) {
+	headers := make(map[string]http.Header)
+	for _, v := range headerArgs {
+		ds, name, value, err := splitHeaderArg(v)
+		if err != nil {
+			return nil, err
+		}
+		if _, ok := headers[ds]; !ok {
+			headers[ds] = make(http.Header)
+		}
+		headers[ds][name] = append(headers[ds][name], strings.TrimSpace(value))
+	}
+	return headers, nil
+}
+
+func splitHeaderArg(arg string) (datasourceAlias, name, value string, err error) {
+	parts := strings.SplitN(arg, "=", 2)
+	if len(parts) != 2 {
+		err = errors.Errorf("Invalid datasource-header option '%s'", arg)
+		return "", "", "", err
+	}
+	datasourceAlias = parts[0]
+	name, value, err = splitHeader(parts[1])
+	return datasourceAlias, name, value, err
+}
+
+func splitHeader(header string) (name, value string, err error) {
+	parts := strings.SplitN(header, ":", 2)
+	if len(parts) != 2 {
+		err = errors.Errorf("Invalid HTTP Header format '%s'", header)
+		return "", "", err
+	}
+	name = http.CanonicalHeaderKey(parts[0])
+	value = parts[1]
+	return name, value, nil
+}