42 lines
1.4 KiB
Go
42 lines
1.4 KiB
Go
package engine
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import (
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"net/http"
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"path"
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)
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// ServeHTTP executes a job as specified by the http request `r`, and sends the
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// result as an http response.
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// This method allows an Engine instance to be passed as a standard http.Handler interface.
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//
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// Note that the protocol used in this method is a convenience wrapper and is not the canonical
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// implementation of remote job execution. This is because HTTP/1 does not handle stream multiplexing,
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// and so cannot differentiate stdout from stderr. Additionally, headers cannot be added to a response
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// once data has been written to the body, which makes it inconvenient to return metadata such
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// as the exit status.
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//
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func (eng *Engine) ServeHTTP(w http.ResponseWriter, r *http.Request) {
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var (
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jobName = path.Base(r.URL.Path)
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jobArgs, exists = r.URL.Query()["a"]
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)
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if !exists {
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jobArgs = []string{}
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}
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w.Header().Set("Job-Name", jobName)
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for _, arg := range jobArgs {
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w.Header().Add("Job-Args", arg)
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}
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job := eng.Job(jobName, jobArgs...)
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job.Stdout.Add(w)
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job.Stderr.Add(w)
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// FIXME: distinguish job status from engine error in Run()
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// The former should be passed as a special header, the former
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// should cause a 500 status
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w.WriteHeader(http.StatusOK)
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// The exit status cannot be sent reliably with HTTP1, because headers
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// can only be sent before the body.
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// (we could possibly use http footers via chunked encoding, but I couldn't find
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// how to use them in net/http)
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job.Run()
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}
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