composer/job-queue: add scaffolding for the job queue API

This is by no means done, and needs more tests, docs and bugfixes,
but push it early so we have a common base to work on.

Based on work by Martin Sehnoutka.

Signed-off-by: Tom Gundersen <teg@jklm.no>

internal/jobqueue/api.go

@@ -0,0 +1,141 @@
+package jobqueue
+
+import (
+	"encoding/json"
+	"log"
+	"net"
+	"net/http"
+	"osbuild-composer/internal/job"
+	"osbuild-composer/internal/pipeline"
+	"osbuild-composer/internal/target"
+
+	"github.com/julienschmidt/httprouter"
+)
+
+type API struct {
+	jobStore    *job.Store
+	pendingJobs <-chan job.Job
+
+	logger *log.Logger
+	router *httprouter.Router
+}
+
+func New(logger *log.Logger, jobs <-chan job.Job) *API {
+	api := &API{
+		jobStore:    job.NewStore(),
+		logger:      logger,
+		pendingJobs: jobs,
+	}
+
+	api.router = httprouter.New()
+	api.router.RedirectTrailingSlash = false
+	api.router.RedirectFixedPath = false
+	api.router.MethodNotAllowed = http.HandlerFunc(methodNotAllowedHandler)
+	api.router.NotFound = http.HandlerFunc(notFoundHandler)
+
+	api.router.POST("/job-queue/v1/jobs", api.addJobHandler)
+	api.router.PATCH("/job-queue/v1/jobs/:job-id", api.updateJobHandler)
+
+	return api
+}
+
+func (api *API) Serve(listener net.Listener) error {
+	server := http.Server{Handler: api}
+
+	err := server.Serve(listener)
+	if err != nil && err != http.ErrServerClosed {
+		return err
+	}
+
+	return nil
+}
+
+func (api *API) ServeHTTP(writer http.ResponseWriter, request *http.Request) {
+	if api.logger != nil {
+		log.Println(request.Method, request.URL.Path)
+	}
+
+	writer.Header().Set("Content-Type", "application/json; charset=utf-8")
+	api.router.ServeHTTP(writer, request)
+}
+
+func methodNotAllowedHandler(writer http.ResponseWriter, request *http.Request) {
+	writer.WriteHeader(http.StatusMethodNotAllowed)
+}
+
+func notFoundHandler(writer http.ResponseWriter, request *http.Request) {
+	writer.WriteHeader(http.StatusNotFound)
+}
+
+func statusResponseOK(writer http.ResponseWriter) {
+	writer.WriteHeader(http.StatusOK)
+}
+
+func statusResponseError(writer http.ResponseWriter, code int, errors ...string) {
+	writer.WriteHeader(code)
+}
+
+func (api *API) addJobHandler(writer http.ResponseWriter, request *http.Request, _ httprouter.Params) {
+	type requestBody struct {
+		JobID string `json:"job-id"`
+	}
+	type replyBody struct {
+		Pipeline pipeline.Pipeline `json:"pipeline"`
+		Target   target.Target     `json:"target"`
+	}
+
+	contentType := request.Header["Content-Type"]
+	if len(contentType) != 1 || contentType[0] != "application/json" {
+		statusResponseError(writer, http.StatusUnsupportedMediaType)
+		return
+	}
+
+	var body requestBody
+	err := json.NewDecoder(request.Body).Decode(&body)
+	if err != nil {
+		statusResponseError(writer, http.StatusBadRequest, "invalid job-id: "+err.Error())
+		return
+	}
+
+	id := body.JobID
+	var req job.Job
+
+	if !api.jobStore.AddJob(id, req) {
+		statusResponseError(writer, http.StatusBadRequest)
+		return
+	}
+
+	req = <-api.pendingJobs
+	api.jobStore.UpdateJob(id, req)
+
+	json.NewEncoder(writer).Encode(replyBody{req.Pipeline, req.Target})
+
+}
+
+func (api *API) updateJobHandler(writer http.ResponseWriter, request *http.Request, params httprouter.Params) {
+	type requestBody struct {
+		Status string `json:"status"`
+	}
+
+	contentType := request.Header["Content-Type"]
+	if len(contentType) != 1 || contentType[0] != "application/json" {
+		statusResponseError(writer, http.StatusUnsupportedMediaType)
+		return
+	}
+
+	var body requestBody
+	err := json.NewDecoder(request.Body).Decode(&body)
+	if err != nil {
+		statusResponseError(writer, http.StatusBadRequest, "invalid status: "+err.Error())
+		return
+	} else if body.Status == "running" {
+		statusResponseOK(writer)
+		return
+	} else if body.Status != "finished" {
+		statusResponseError(writer, http.StatusBadRequest, "invalid status: "+body.Status)
+		return
+	}
+
+	api.jobStore.DeleteJob(params.ByName("job-id"))
+	statusResponseOK(writer)
+}