[feature] S3 support (#674)

* feat: vendor minio client

* feat: introduce storage package with s3 support

* feat: serve s3 files directly

this saves a lot of bandwith as the files are fetched from the object
store directly

* fix: use explicit local storage in tests

* feat: integrate s3 storage with the main server

* fix: add s3 config to cli tests

* docs: explicitly set values in example config

also adds license header to the storage package

* fix: use better http status code on s3 redirect

HTTP 302 Found is the best fit, as it signifies that the resource
requested was found but not under its presumed URL

307/TemporaryRedirect would mean that this resource is usually located
here, not in this case

303/SeeOther indicates that the redirection does not link to the
requested resource but to another page

* refactor: use context in storage driver interface

1 files changed, 123 insertions, 0 deletions

diff --git a/vendor/github.com/dustin/go-humanize/si.go b/vendor/github.com/dustin/go-humanize/si.go
new file mode 100644
index 000000000..ae659e0e4
--- /dev/null
+++ b/vendor/github.com/dustin/go-humanize/si.go
@@ -0,0 +1,123 @@
+package humanize
+
+import (
+	"errors"
+	"math"
+	"regexp"
+	"strconv"
+)
+
+var siPrefixTable = map[float64]string{
+	-24: "y", // yocto
+	-21: "z", // zepto
+	-18: "a", // atto
+	-15: "f", // femto
+	-12: "p", // pico
+	-9:  "n", // nano
+	-6:  "µ", // micro
+	-3:  "m", // milli
+	0:   "",
+	3:   "k", // kilo
+	6:   "M", // mega
+	9:   "G", // giga
+	12:  "T", // tera
+	15:  "P", // peta
+	18:  "E", // exa
+	21:  "Z", // zetta
+	24:  "Y", // yotta
+}
+
+var revSIPrefixTable = revfmap(siPrefixTable)
+
+// revfmap reverses the map and precomputes the power multiplier
+func revfmap(in map[float64]string) map[string]float64 {
+	rv := map[string]float64{}
+	for k, v := range in {
+		rv[v] = math.Pow(10, k)
+	}
+	return rv
+}
+
+var riParseRegex *regexp.Regexp
+
+func init() {
+	ri := `^([\-0-9.]+)\s?([`
+	for _, v := range siPrefixTable {
+		ri += v
+	}
+	ri += `]?)(.*)`
+
+	riParseRegex = regexp.MustCompile(ri)
+}
+
+// ComputeSI finds the most appropriate SI prefix for the given number
+// and returns the prefix along with the value adjusted to be within
+// that prefix.
+//
+// See also: SI, ParseSI.
+//
+// e.g. ComputeSI(2.2345e-12) -> (2.2345, "p")
+func ComputeSI(input float64) (float64, string) {
+	if input == 0 {
+		return 0, ""
+	}
+	mag := math.Abs(input)
+	exponent := math.Floor(logn(mag, 10))
+	exponent = math.Floor(exponent/3) * 3
+
+	value := mag / math.Pow(10, exponent)
+
+	// Handle special case where value is exactly 1000.0
+	// Should return 1 M instead of 1000 k
+	if value == 1000.0 {
+		exponent += 3
+		value = mag / math.Pow(10, exponent)
+	}
+
+	value = math.Copysign(value, input)
+
+	prefix := siPrefixTable[exponent]
+	return value, prefix
+}
+
+// SI returns a string with default formatting.
+//
+// SI uses Ftoa to format float value, removing trailing zeros.
+//
+// See also: ComputeSI, ParseSI.
+//
+// e.g. SI(1000000, "B") -> 1 MB
+// e.g. SI(2.2345e-12, "F") -> 2.2345 pF
+func SI(input float64, unit string) string {
+	value, prefix := ComputeSI(input)
+	return Ftoa(value) + " " + prefix + unit
+}
+
+// SIWithDigits works like SI but limits the resulting string to the
+// given number of decimal places.
+//
+// e.g. SIWithDigits(1000000, 0, "B") -> 1 MB
+// e.g. SIWithDigits(2.2345e-12, 2, "F") -> 2.23 pF
+func SIWithDigits(input float64, decimals int, unit string) string {
+	value, prefix := ComputeSI(input)
+	return FtoaWithDigits(value, decimals) + " " + prefix + unit
+}
+
+var errInvalid = errors.New("invalid input")
+
+// ParseSI parses an SI string back into the number and unit.
+//
+// See also: SI, ComputeSI.
+//
+// e.g. ParseSI("2.2345 pF") -> (2.2345e-12, "F", nil)
+func ParseSI(input string) (float64, string, error) {
+	found := riParseRegex.FindStringSubmatch(input)
+	if len(found) != 4 {
+		return 0, "", errInvalid
+	}
+	mag := revSIPrefixTable[found[2]]
+	unit := found[3]
+
+	base, err := strconv.ParseFloat(found[1], 64)
+	return base * mag, unit, err
+}