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Upgrade rack-proxy to v0.7.2

Stan Hu requested to merge sh-update-rack-proxy into master

What does this MR do and why?

This fixes a bug that manifested with the webpack-dev-server and the thin Web server.

When a chunked transfer is proxied from rack-proxy (see diagram below), the proxied HTTP response would contain the original Transfer-Encoding: chunked HTTP header. However, the body would be stripped of the chunked encoding headers. As a result, Workhorse would fail to parse the body with the error:

httputil: ReverseProxy read error during body copy: invalid byte in chunk length

This occurred because the Golang chunked decoder expected to parse a length represented as an ASCII number followed by a \r\n. Instead, the first byte was a binary character from the gzipped data.

This does not occur with Puma because Puma initiates a request with an HTTP/1.0 header and explicitly disables chunked transfers.

https://github.com/ncr/rack-proxy/pull/59 fixes this problem by dropping the Transfer-Encoding: chunked header so that Workhorse won't handle the HTTP response as a chunked transfer.

See gitlab-development-kit#1443 (comment 880747269) for more details.

Relates to #352649 (closed)

Diff:

Closes gitlab-development-kit#1443 (closed)

Screenshots or screen recordings

The problem happens at step 7:

sequenceDiagram
    autonumber
    curl->>NGINX: GET /assets/webpack/0.chunk.js
    NGINX->>Workhorse: GET /assets/webpack/0.chunk.js
    Workhorse->>Thin: GET /assets/webpack/0.chunk.js
    Thin->>Thin: DevServerMiddleware proxies to rack-proxy
    Thin->>Webpack: thin/request: GET /assets/webpack/0.chunk.js HTTP/1.1
    Webpack->>Thin: HTTP/1.1 chunked, gzip 
    Thin->>Workhorse: gzip body (chunked headers stripped)
    Workhorse->>NGINX: Empty body
    NGINX->>curl: Empty boxy

rack-proxy returns the headers and body as-is, keeping Transfer-Encoding: chunked. However, the body is the original JavaScript asset with the stripped the chunking headers.

How to set up and validate locally

  1. Run gdk thin.
  2. Try to load a project page. You should see missing elements. Alternatively you can curl an asset: curl https://gdk.tests:3443/assets/webpack/0.chunk.js.
  3. Check out this branch.
  4. Hit CTRL-C to cancel thin and run gdk thin again.
  5. Repeat step 2

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

Edited by Ash McKenzie

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