Cadence Stack Reverse Proxy (Redo)

[kenellorando]

This PR is a redo of #233. #233 originally introduced the reverse proxy service, but broke the rate limiter and SSE, so I'm back again with a more thoughtful approach.

Reverse Proxy Service

The main feature of this PR is a built-in Reverse Proxy service provided by an nginx container which routes inbound connections to the API server and Icecast stream.

Cadence users can now easily serve their radios publicly by simply providing the reverse proxy service with their own domain names.

This naturally forced about some improvements to other parts of Cadence, as you will see.

cadenceradio.com demo deployed using Compose

In order to actually test the reverse proxy service in a production environment, I've moved the demo site, CadenceRadio.com, off my Kubernetes cluster and onto a "traditional" Linux Server using Cadence's Docker Compose.

I had it on my Kubernetes cluster mostly for personal interest reasons, but I may actually keep it deployed through Compose for the foreseeable future since it's how I expect users to actually run their Cadence stacks anyway.

I opened #236 to hopefully make installation for the user even easier.

Rate Limiter Updated

We introduce a better rate limiter IP checker that works with or without the new reverse proxy.

cadence/cadence/server/db_redis.go

Lines 56 to 67 in 7d9fd8b

	func checkIP(r *http.Request) (ip string, err error) {
	// We look at the remote address and check the IP.
	// If for some reason no remote IP is there, we error to reject.
	if r.RemoteAddr != "" {
	ip, _, err := net.SplitHostPort(r.RemoteAddr)
	if err != nil || ip == "" {
	return "", err
	}
	return ip, nil
	}
	return "", err
	}

Reliable SSE

The default reverse proxy configuration provided also reliably handles SSE connections.

cadence/config/nginx.conf

Lines 22 to 31 in 7d9fd8b

	location /api/radiodata/sse {
	proxy_read_timeout 86400;
	proxy_send_timeout 86400;
	proxy_set_header Connection '';
	proxy_http_version 1.1;
	chunked_transfer_encoding off;
	proxy_buffering off;
	proxy_cache off;
	proxy_pass http://cadence:8080/api/radiodata/sse;
	}

UI code is also modified so it will try to close its current SSE connection when it encounters an error before trying to create a new connection.

Error Handling

We added some handling for specific errors related to Postgres DB startup. If a Cadence replica is launched and the metadata database or table already exist, it won't skip repopulation.

cadence/cadence/server/db_postgres.go

Lines 89 to 98 in 7d9fd8b

	_, err = dbp.Exec(createTable)
	if err != nil {
	if err.(*pq.Error).Code == "42P07" {
	// 42P10 indicates an existing metadata table configured by another Cadence instance is still running.
	clog.Info("postgresInit", "Metadata database already exists")
	} else {
	clog.Error("postgresPopulate", "Failed to build database table!", err)
	return err
	}
	}

Reorganization

The repository has been reorganized so there is no longer a top-level directory for Icecast or Liquidsoap. Their Dockerfiles have been moved within a new stream/ directory.

All config files meant for the user to configure have been moved to a new top-level config/ directory. With everything in one place now and renamed with clarity, it should be simpler for someone to set up a stack.

Minor Code Updates

• We do a handful of other things in the Docker Compose, such as correcting usage of expose vs ports, and correcting context to a more accurate dockerfile.
• The Compose and Makefile have been updated to support the newly reorganized repository.
• The Icecast monitor is slightly reorganized.
• Fixed incorrect logging names.
• Trimmed whitespace from search API input.
• New architecture diagram.

---

This fixes #227.