feature: add stats api in daemon side

[allencloud]

Signed-off-by: Allen Sun allensun.shl@alibaba-inc.com

Ⅰ. Describe what this PR did

This PR adds the stats API in daemon side. Here we defined the API:

  /containers/{id}/stats:
    get:
      summary: "Get container stats based on resource usage"
      produces: ["application/json"]
      responses:
        200:
          description: container stats
          schema:
            $ref: "#/definitions/ContainerStats"
        404:
          $ref: "#/responses/404ErrorResponse"
        500:
          $ref: "#/responses/500ErrorResponse"
      parameters:
        - name: "id"
          in: "path"
          required: true
          description: "ID or name of the container"
          type: "string"
        - name: "stream"
          in: "query"
          description: "Stream the output. If false, the stats will be output once and then it will disconnect."
          type: "boolean"
          default: true

Ⅱ. Does this pull request fix one issue?

this fixes the first part of issue #2086

Ⅲ. Why don't you add test cases (unit test/integration test)? (你真的觉得不需要加测试吗？)

let me add client side implementation and then add test case.

Ⅳ. Describe how to verify it

and we can also set the stream query as true to stream stats of a container.

Ⅴ. Special notes for reviews

none

[codecov-io]

Codecov Report

Merging #2112 into master will increase coverage by 4.73%.
The diff coverage is 0.78%.

@@            Coverage Diff             @@
##           master    #2112      +/-   ##
==========================================
+ Coverage   59.63%   64.36%   +4.73%     
==========================================
  Files         208      209       +1     
  Lines       16482    16596     +114     
==========================================
+ Hits         9829    10682     +853     
+ Misses       5453     4584     -869     
- Partials     1200     1330     +130

Flag	Coverage Δ
#criv1alpha1test	32.77% <0.78%> (-0.37%)	⬇️
#criv1alpha2test	33.55% <0.78%> (?)
#integrationtest	39.26% <0.78%> (-0.26%)	⬇️
#unittest	23.72% <0%> (-0.18%)	⬇️

Impacted Files	Coverage Δ
daemon/mgr/container_types.go	79.54% <ø> (ø)	⬆️
daemon/mgr/container.go	56.44% <ø> (+0.57%)	⬆️
cri/v1alpha2/cri_utils.go	82.33% <0%> (+27.18%)	⬆️
cri/v1alpha1/cri_utils.go	83.64% <0%> (ø)	⬆️
apis/server/container_bridge.go	75.83% <0%> (-3.55%)	⬇️
ctrd/container.go	43.19% <0%> (-0.32%)	⬇️
daemon/mgr/container_stats.go	0% <0%> (ø)
apis/server/router.go	91.83% <100%> (+0.05%)	⬆️
cri/v1alpha1/cri.go	63.44% <0%> (-0.35%)	⬇️
... and 12 more

[fuweid]

since we don't have event listener for specific container right now, I think we should check the status of container before get stat. If the status has been changed from running to stopped, we should exit the loop.

[fuweid]

I checked the existing moby api and it doesn't exit and will wait for next restart.

[fuweid]

If we don't support this right now, could we remove this part and add the TODO?

[fuweid]

LGTM