websrv

websrv

This is a little webserver implementation using only dependencies from the go standard library (besides testing and logging). The webserver is supposed to serve a folder containing e.g. a static website.

The server package contains a collection of http.Handler implementations which may be reused in other projects. The filesystem package contains a readonly in-memory-filesystem implementation.

Server package features

Logs are (without -pretty option) are provided in a GCP compatible JSON format.

The following limited handler features are provided in the server package:

• FileServer: implements the main logic for providing the requested file or an optional fallback-file.
• Headers: Static Headers can be easily configured.
• Gzip: Supported for on-demand and in-memory-filesystem.
• Caching: Support via ETag and If-None-Match HTTP-Headers
• Request-ID: All logs provide a unique request-id to correlate different logs to a given request.
• Access-Log: Basic access-logging.
• Timer: Detailed timing reports, set log level to debug to get the output.
• CspReplace: See my blog about fixing Angular CSP regarding style-src.

Usage

Docker container

You can use the ngergs/websrv docker container, the entrypoint is set to the websrv executable.

Binary build

All releases starting with v1.4.3 have binary builds attached to them for linux, windows and osx.

Compilation from Source

Compile from source:

git clone https://github.com/ngergs/websrv
go build ./cmd/websrv

Usage

The path to this folder has to be provided as command line argument. There are a number of various optional settings.

Usage: ./websrv {options} [target-path]
Options:
  -access-log
        Prints an access log for the file server endpoint.
  -config-file string
        Optional file that contains more involved config settings, see server/config.go for the structure.
  -debug
        Log debug level
  -fallback-file string
        Filepath relative to targetDir which serves as fallback. Set to empty to disable. (default "index.html")
  -gzip
        Whether to send gzip encoded response. See config-file for setting the detailed types. As default gzip is used when activated for test/css, text/html and application/javascript (default true)
  -gzip-level int
        The compression level used for gzip compression. See the golang gzip documentation for details. Only applies to on-the-fly compression. The in-memory-fs (when used) uses for static files always gzip.BestCompression (default 1)
  -health
        Whether to start the health check endpoint (under a separate port) (default true)
  -health-access-log
        Prints an access log for the health check endpoint to stdout.
  -health-port int
        Different port under which the health check endpoint runs. (default 8081)
  -help
        Prints the help.
  -idle-timeout int
        Timeout for idle TCP connections with keep-alive in seconds. (default 30)
  -in-memory-fs
        Whether to use a in-memory-filesystem. I.e. prefetch the target directory into the heap.
  -metrics
        Whether to start the metrics endpoint (under a separate port)
  -metrics-access-log
        Prints an access log for the metrics endpoint to stdout.
  -metrics-namespace string
        Prometheus namespace for the collected metrics. (default "websrv")
  -metrics-port int
        TCP-Port under which the metrics endpoint runs. (default 9090)
  -port int
        Port under which the webserver runs. (default 8080)
  -pretty
        Activates zerolog pretty logging
  -read-timeout int
        Timeout to read the entire request in seconds. (default 10)
  -shutdown-delay int
        Delay before shutting down the server in seconds. To make sure that the load balancing of the surrounding infrastructure had time to update. (default 5)
  -shutdown-timeout int
        Timeout for the graceful shutdown in seconds. (default 10)
  -write-timeout int
        Timeout to write the complete response in seconds. (default 10)

Advanced configs

More involved configs can be provided via the config-file option. See config-example.json for an exmaple. The structure is as follows:

type Config struct {
	// Static headers to be set
	Headers           map[string]string  `json:"headers,omitempty"`
	AngularCspReplace *AngularCspReplace `json:"angular-csp-replace,omitempty"`
	// Mapping of file extension to Media-Type, needed due to https://github.com/golang/go/issues/32350
	MediaTypeMap map[string]string `json:"media-type-map,omitempty"`
	// Media-Types for which gzipping should be applied (if activated and client has set the Accept-Encoding: gzip HTTP-Header)
	GzipMediaTypes []string `json:"gzip-media-types,omitempty"`
}

type AngularCspReplace struct {
	// (secret) placeholder which will be replaced with the session id when serving
	VariableName    string `json:"variable-name"`
	// Regex for which files the Variable-Name should be replaced
	FileNamePattern string `json:"file-name-regex,omitempty"`
	// Name of the session-id cookie
	CookieName      string `json:"cookie-name"`
	// Max-Age setting for the session-id cookie, 30 seconds should be sufficient
	CookieMaxAge    int    `json:"cookie-max-age"`
}