support gzipped GUI files

[brycekahle]

What does this PR do?

1. Adds support for gzipped files in the agent GUI
2. gzips all used files that are not already compressed
3. Removes FontAwesome.otf which is a desktop font file
4. Renames stylesheet.scss to .stylesheet.scss so it is not embedded in the Go binary.

Saves ~1MB from the binary size.

Motivation

Describe how to test/QA your changes

Manually checked with curl and loading the GUI in Chrome on macOS

Possible Drawbacks / Trade-offs

Ideally the javascript.js file would not be gzipped in-repo, but that would require adding a build process for these files. They seem to change very rarely, so I opted for the space savings at the moment.

Additional Notes

Before agent binary size 212624296

8.3K	./css/codemirror.css
15K	./css/stylesheet.css
14K	./css/stylesheet.scss
31K	./css/font-awesome.min.css
68K	./css
8.7K	./images/datadog_icon_white.svg
362K	./images/dd_bkgrnd.png
370K	./images
23K	./js/purify.min.js
359K	./js/codemirror.js
311	./js/polyfills.js
88K	./js/jquery-3.5.1.min.js
27K	./js/javascript.js
3.7K	./js/yaml.js
499K	./js
434K	./fonts/fontawesome-webfont.svg
132K	./fonts/FontAwesome.otf
76K	./fonts/fontawesome-webfont.woff2
162K	./fonts/fontawesome-webfont.ttf
96K	./fonts/fontawesome-webfont.woff
162K	./fonts/fontawesome-webfont.eot
1.1M	./fonts
2.0M	.

After agent binary size 211650896 (diff -973400)

7.0K	./css/font-awesome.min.css.gz
2.9K	./css/stylesheet.css.gz
2.6K	./css/codemirror.css.gz
13K	./css
3.4K	./images/datadog_icon_white.svg.gz
362K	./images/dd_bkgrnd.png
365K	./images
209	./js/polyfills.js.gz
6.2K	./js/javascript.js.gz
1.3K	./js/yaml.js.gz
99K	./js/codemirror.js.gz
8.6K	./js/purify.min.js.gz
31K	./js/jquery-3.5.1.min.js.gz
146K	./js
96K	./fonts/fontawesome-webfont.eot.gz
96K	./fonts/fontawesome-webfont.ttf.gz
132K	./fonts/fontawesome-webfont.svg.gz
76K	./fonts/fontawesome-webfont.woff2
96K	./fonts/fontawesome-webfont.woff
495K	./fonts
1018K	.

Potential future space savings:

1. Subsetting the fonts
2. Minimizing .js and .css files

[agent-platform-auto-pr]

Test changes on VM

Use this command from test-infra-definitions to manually test this PR changes on a VM:

inv create-vm --pipeline-id=49081191 --os-family=ubuntu

Note: This applies to commit 31c8691

[cit-pr-commenter]

Regression Detector

Regression Detector Results

Metrics dashboard
Target profiles
Run ID: 2ac0182e-943d-4b02-89cc-615fa6af6953

Baseline: 28e835f
Comparison: 31c8691
Diff

Optimization Goals: ✅ No significant changes detected

Fine details of change detection per experiment

perf	experiment	goal	Δ mean %	Δ mean % CI	trials	links
➖	basic_py_check	% cpu utilization	+2.73	[-1.13, +6.58]	1	Logs
➖	file_tree	memory utilization	+0.57	[+0.43, +0.71]	1	Logs
➖	otel_to_otel_logs	ingress throughput	+0.49	[-0.19, +1.17]	1	Logs
➖	file_to_blackhole_1000ms_latency_linear_load	egress throughput	+0.49	[+0.00, +0.97]	1	Logs
➖	file_to_blackhole_1000ms_latency	egress throughput	+0.32	[-0.17, +0.80]	1	Logs
➖	file_to_blackhole_300ms_latency	egress throughput	+0.09	[-0.10, +0.27]	1	Logs
➖	file_to_blackhole_0ms_latency	egress throughput	+0.03	[-0.44, +0.50]	1	Logs
➖	file_to_blackhole_100ms_latency	egress throughput	+0.01	[-0.32, +0.33]	1	Logs
➖	tcp_dd_logs_filter_exclude	ingress throughput	-0.00	[-0.01, +0.01]	1	Logs
➖	uds_dogstatsd_to_api	ingress throughput	-0.03	[-0.12, +0.06]	1	Logs
➖	quality_gate_idle	memory utilization	-0.05	[-0.10, -0.01]	1	Logs bounds checks dashboard
➖	file_to_blackhole_500ms_latency	egress throughput	-0.15	[-0.39, +0.10]	1	Logs
➖	quality_gate_idle_all_features	memory utilization	-0.24	[-0.34, -0.14]	1	Logs bounds checks dashboard
➖	uds_dogstatsd_to_api_cpu	% cpu utilization	-0.33	[-1.06, +0.40]	1	Logs
➖	pycheck_lots_of_tags	% cpu utilization	-0.39	[-3.74, +2.96]	1	Logs
➖	tcp_syslog_to_blackhole	ingress throughput	-0.57	[-0.63, -0.52]	1	Logs

Bounds Checks: ❌ Failed

perf	experiment	bounds_check_name	replicates_passed	links
❌	file_to_blackhole_0ms_latency	lost_bytes	5/10
❌	file_to_blackhole_100ms_latency	lost_bytes	5/10
✅	file_to_blackhole_0ms_latency	memory_usage	10/10
✅	file_to_blackhole_1000ms_latency	memory_usage	10/10
✅	file_to_blackhole_1000ms_latency_linear_load	memory_usage	10/10
✅	file_to_blackhole_100ms_latency	memory_usage	10/10
✅	file_to_blackhole_300ms_latency	memory_usage	10/10
✅	file_to_blackhole_500ms_latency	memory_usage	10/10
✅	quality_gate_idle	memory_usage	10/10	bounds checks dashboard
✅	quality_gate_idle_all_features	memory_usage	10/10	bounds checks dashboard

Explanation

Confidence level: 90.00%
Effect size tolerance: |Δ mean %| ≥ 5.00%

Performance changes are noted in the perf column of each table:

• ✅ = significantly better comparison variant performance
• ❌ = significantly worse comparison variant performance
• ➖ = no significant change in performance

A regression test is an A/B test of target performance in a repeatable rig, where "performance" is measured as "comparison variant minus baseline variant" for an optimization goal (e.g., ingress throughput). Due to intrinsic variability in measuring that goal, we can only estimate its mean value for each experiment; we report uncertainty in that value as a 90.00% confidence interval denoted "Δ mean % CI".

For each experiment, we decide whether a change in performance is a "regression" -- a change worth investigating further -- if all of the following criteria are true:

1. Its estimated |Δ mean %| ≥ 5.00%, indicating the change is big enough to merit a closer look.

2. Its 90.00% confidence interval "Δ mean % CI" does not contain zero, indicating that if our statistical model is accurate, there is at least a 90.00% chance there is a difference in performance between baseline and comparison variants.

3. Its configuration does not mark it "erratic".

[misteriaud]

🔨 warning: ‏A lot of the files that you compressed with gzip are source code that can be worked on. So a better approach is to compress those files at the Agent build step (with omnibus).

[GustavoCaso]

What if we group all header logic together?

Here is a suggestion of how it could look like:

func serveAsset(gzipSupport bool, assetPath string) ([]byte, error) {
	var rdr io.ReadCloser
	rdr, err := viewsFS.Open(assetPath + ".gz")
	if err != nil && os.IsNotExist(err) {
		rdr, err = viewsFS.Open(assetPath)
	}
	if err != nil {
		return nil, err
	}
	defer rdr.Close()

	if !gzipSupport {
		// ungzip on the fly
		gzReader, err := gzip.NewReader(rdr)
		if err != nil {
			return nil, err
		}
		// ensure underlying io.Reader is closed
		defer gzReader.Close()
		rdr = gzReader
	}

	data, err := io.ReadAll(rdr)
	if err != nil {
		return nil, err
	}
	return data, nil
}

func serveAssets(w http.ResponseWriter, req *http.Request) {
	assetPath := path.Join("views", "private", req.URL.Path)
	gzipSupport := strings.Contains(req.Header.Get("Accept-Encoding"), "gzip")
	data, err := serveAsset(gzipSupport, assetPath)
	if err != nil {
		if os.IsNotExist(err) {
			http.Error(w, err.Error(), http.StatusNotFound)
		} else {
			http.Error(w, err.Error(), http.StatusInternalServerError)
		}
		return
	}
	
	if gzipSupport {
		w.Header().Set("Content-Encoding", "gzip")
	}
	
	w.Header().Set("Content-Type", mime.TypeByExtension(filepath.Ext(assetPath)))
	w.Header().Set("Content-Length", strconv.Itoa(len(data)))
	_, _ = w.Write(data)
}

Let me know what you think :smi

[brycekahle]

Updated

[brycekahle]

🔨 warning: ‏A lot of the files that you compressed with gzip are source code that can be worked on. So a better approach is to compress those files at the Agent build step (with omnibus).

I did mention this in the PR description.

Ideally the javascript.js file would not be gzipped in-repo, but that would require adding a build process for these files. They seem to change very rarely, so I opted for the space savings at the moment.

It is non-trivial to add the build process, so this was a temporary solution.

[brycekahle]

Closing because we are going to stop embedding these files in the binary, in a separate PR.