hugo/resource/integrity/integrity.go
Bjørn Erik Pedersen dea71670c0
Add Hugo Piper with SCSS support and much more
Before this commit, you would have to use page bundles to do image processing etc. in Hugo.

This commit adds

* A new `/assets` top-level project or theme dir (configurable via `assetDir`)
* A new template func, `resources.Get` which can be used to "get a resource" that can be further processed.

This means that you can now do this in your templates (or shortcodes):

```bash
{{ $sunset := (resources.Get "images/sunset.jpg").Fill "300x200" }}
```

This also adds a new `extended` build tag that enables powerful SCSS/SASS support with source maps. To compile this from source, you will also need a C compiler installed:

```
HUGO_BUILD_TAGS=extended mage install
```

Note that you can use output of the SCSS processing later in a non-SCSSS-enabled Hugo.

The `SCSS` processor is a _Resource transformation step_ and it can be chained with the many others in a pipeline:

```bash
{{ $css := resources.Get "styles.scss" | resources.ToCSS | resources.PostCSS | resources.Minify | resources.Fingerprint }}
<link rel="stylesheet" href="{{ $styles.RelPermalink }}" integrity="{{ $styles.Data.Digest }}" media="screen">
```

The transformation funcs above have aliases, so it can be shortened to:

```bash
{{ $css := resources.Get "styles.scss" | toCSS | postCSS | minify | fingerprint }}
<link rel="stylesheet" href="{{ $styles.RelPermalink }}" integrity="{{ $styles.Data.Digest }}" media="screen">
```

A quick tip would be to avoid the fingerprinting part, and possibly also the not-superfast `postCSS` when you're doing development, as it allows Hugo to be smarter about the rebuilding.

Documentation will follow, but have a look at the demo repo in https://github.com/bep/hugo-sass-test

New functions to create `Resource` objects:

* `resources.Get` (see above)
* `resources.FromString`: Create a Resource from a string.

New `Resource` transformation funcs:

* `resources.ToCSS`: Compile `SCSS` or `SASS` into `CSS`.
* `resources.PostCSS`: Process your CSS with PostCSS. Config file support (project or theme or passed as an option).
* `resources.Minify`: Currently supports `css`, `js`, `json`, `html`, `svg`, `xml`.
* `resources.Fingerprint`: Creates a fingerprinted version of the given Resource with Subresource Integrity..
* `resources.Concat`: Concatenates a list of Resource objects. Think of this as a poor man's bundler.
* `resources.ExecuteAsTemplate`: Parses and executes the given Resource and data context (e.g. .Site) as a Go template.

Fixes #4381
Fixes #4903
Fixes #4858
2018-07-06 11:46:12 +02:00

106 lines
2.8 KiB
Go

// Copyright 2018 The Hugo Authors. All rights reserved.
//
// 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 integrity
import (
"crypto/md5"
"crypto/sha256"
"crypto/sha512"
"encoding/base64"
"encoding/hex"
"fmt"
"hash"
"io"
"github.com/gohugoio/hugo/resource"
)
const defaultHashAlgo = "sha256"
// Client contains methods to fingerprint (cachebusting) and other integrity-related
// methods.
type Client struct {
rs *resource.Spec
}
// New creates a new Client with the given specification.
func New(rs *resource.Spec) *Client {
return &Client{rs: rs}
}
type fingerprintTransformation struct {
algo string
}
func (t *fingerprintTransformation) Key() resource.ResourceTransformationKey {
return resource.NewResourceTransformationKey("fingerprint", t.algo)
}
// Transform creates a MD5 hash of the Resource content and inserts that hash before
// the extension in the filename.
func (t *fingerprintTransformation) Transform(ctx *resource.ResourceTransformationCtx) error {
algo := t.algo
var h hash.Hash
switch algo {
case "md5":
h = md5.New()
case "sha256":
h = sha256.New()
case "sha512":
h = sha512.New()
default:
return fmt.Errorf("unsupported crypto algo: %q, use either md5, sha256 or sha512", algo)
}
io.Copy(io.MultiWriter(h, ctx.To), ctx.From)
d, err := digest(h)
if err != nil {
return err
}
ctx.Data["Integrity"] = integrity(algo, d)
ctx.AddOutPathIdentifier("." + hex.EncodeToString(d[:]))
return nil
}
// Fingerprint applies fingerprinting of the given resource and hash algorithm.
// It defaults to sha256 if none given, and the options are md5, sha256 or sha512.
// The same algo is used for both the fingerprinting part (aka cache busting) and
// the base64-encoded Subresource Integrity hash, so you will have to stay away from
// md5 if you plan to use both.
// See https://developer.mozilla.org/en-US/docs/Web/Security/Subresource_Integrity
func (c *Client) Fingerprint(res resource.Resource, algo string) (resource.Resource, error) {
if algo == "" {
algo = defaultHashAlgo
}
return c.rs.Transform(
res,
&fingerprintTransformation{algo: algo},
)
}
func integrity(algo string, sum []byte) string {
encoded := base64.StdEncoding.EncodeToString(sum)
return fmt.Sprintf("%s-%s", algo, encoded)
}
func digest(h hash.Hash) ([]byte, error) {
sum := h.Sum(nil)
//enc := hex.EncodeToString(sum[:])
return sum, nil
}