feature: dfdaemon supports proxing https registries

[lowzj]

Signed-off-by: lowzj [email protected]

---

Ⅰ. Describe what this PR did

This pull request implements a way to support registries which use https schema in dfdaemon's proxy pattern:

• configure docker daemon
  • set dfdaemon host as http_proxy
  • set your registry hosts as insecure-registries
  • bypass proxy for your registry auth hosts
• dfdaemon get the http requests, change them to https schema and send https request to the real registries

Ⅱ. Does this pull request fix one issue?

fixes #205
related #347

Ⅲ. Why don't you add test cases (unit test/integration test)?

Ⅳ. Describe how to verify it

Here's a example to pull images from a https registry(registry.cn-hangzhou.aliyuncs.com) by using proxy pattern:

• create dfdaemon's config file: /etc/dragonfly/dfdaemon.yml, and start dfdaemon

  registries:
      - regx: "^registry.cn-hangzhou.aliyuncs.com$"
        schema: https
        host: registry.cn-hangzhou.aliyuncs.com

• change your docker daemon config file: /etc/docker/daemon.json, and restart docker daemon

  {
      "insecure-registries" : [
          "registry.cn-hangzhou.aliyuncs.com"
      ],
      "proxies": {
          "default": {
              "httpProxy": "http://127.0.0.1:65001",
          }
      }
  }

• pull a image by dragonfly

  docker pull registry.cn-hangzhou.aliyuncs.com/dragonflyoss/supernode:0.2.1

Ⅴ. Special notes for reviews

@starnop @godliness

[codecov-io]

Codecov Report

Merging #410 into master will increase coverage by 0.78%.
The diff coverage is 95.31%.

@@            Coverage Diff             @@
##           master     #410      +/-   ##
==========================================
+ Coverage      67%   67.79%   +0.78%     
==========================================
  Files          50       51       +1     
  Lines        2243     2304      +61     
==========================================
+ Hits         1503     1562      +59     
- Misses        669      671       +2     
  Partials       71       71

Impacted Files	Coverage Δ
dfget/config/config.go	84.84% <ø> (ø)	⬆️
dfdaemon/muxconf/muxconf.go	100% <100%> (ø)	⬆️
dfdaemon/global/global.go	92.3% <50%> (ø)	⬆️
dfdaemon/config/config.go	96.72% <96.72%> (ø)

---

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[godliness]

LGTM

[starnop]

Could you please write a demo here and update the docs ASAP.

[lowzj]

I have add an example here.

[starnop]

LGTM.