intial commit

.dockerignore

@@ -0,0 +1,3 @@
+/test/
+/test.yaml
+/gcal-sync

.gitignore

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+/test/
+/test.yaml
+/gcal-sync
+vendor/

Dockerfile

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+FROM stagex/busybox:sx2024.09.0@sha256:d34bfa56566aa72d605d6cbdc154de8330cf426cfea1bc4ba8013abcac594395 AS busybox
+FROM stagex/ca-certificates:sx2024.09.0@sha256:33787f1feb634be4232a6dfe77578c1a9b890ad82a2cf18c11dd44507b358803 AS ca-certificates
+FROM stagex/go:sx2024.09.0@sha256:56f511d92dcc6c1910115d8b19dd984b6cd682d1d3e9b72456e3b95f7b141fee AS go
+
+FROM scratch AS builder
+
+ENV CGO_ENABLED=0
+
+COPY --from=busybox . .
+COPY --from=go . .
+COPY --from=ca-certificates . .
+
+ADD . /src/gcal-sync
+
+WORKDIR /src/gcal-sync
+
+RUN go build -o /app
+
+FROM scratch
+
+WORKDIR /
+
+COPY --from=ca-certificates . .
+COPY --from=builder /app /app
+
+ENTRYPOINT ["/app"]

config/config.go

@@ -0,0 +1,104 @@
+package config
+
+import (
+	"context"
+	"fmt"
+	"net/http"
+	"os"
+
+	"github.com/emersion/go-ical"
+	"github.com/emersion/go-webdav"
+	"github.com/emersion/go-webdav/caldav"
+	"gopkg.in/yaml.v3"
+)
+
+type Config struct {
+	Server    string         `yaml:"server"`
+	Username  string         `yaml:"username"`
+	Password  string         `yaml:"password"`
+	Calendars []CalendarSync `yaml:"calendars"`
+}
+
+type CalendarSync struct {
+	Name        string `yaml:"name"`
+	Destination string `yaml:"destination"`
+	URL         string `yaml:"url"`
+}
+
+func (item *CalendarSync) Sync(ctx context.Context, cfg *Config) error {
+	webdavClient := webdav.HTTPClientWithBasicAuth(http.DefaultClient, cfg.Username, cfg.Password)
+
+	cc, err := caldav.NewClient(webdavClient, cfg.Server)
+	if err != nil {
+		return fmt.Errorf("failed to construct a CalDAV client: %w", err)
+	}
+
+	calPath, err := CalendarPath(ctx, cc, cfg.Username, item.Destination)
+	if err != nil {
+		return fmt.Errorf("failed to find destination calendar path: %w", err)
+	}
+
+	resp, err := http.Get(item.URL)
+	if err != nil {
+		return fmt.Errorf("failed to sync %s: %w", item.Name, err)
+	}
+
+	defer resp.Body.Close()
+
+	if resp.StatusCode != http.StatusOK {
+		return fmt.Errorf("source returned non-200 status code: %s", resp.Status)
+	}
+
+	calendarData, err := ical.NewDecoder(resp.Body).Decode()
+	if err != nil {
+		return fmt.Errorf("failed to decode source calendar data: %w", err)
+	}
+
+	// if err := ical.NewEncoder(os.Stdout).Encode(calendarData); err == nil {
+	// 	os.Exit(0)
+	// }
+	
+	if _, err := cc.PutCalendarObject(ctx, calPath, calendarData); err != nil {
+		return fmt.Errorf("failed to push calendar data to destination: %w", err)
+	}
+
+	return nil
+}
+
+func CalendarPath(ctx context.Context, cc *caldav.Client, username, calendarName string) (string, error) {
+	homeSet, err := cc.FindCalendarHomeSet(ctx, username)
+	if err != nil {
+		return "", fmt.Errorf("failed to find home set for %s: %w", username, err)
+	}
+
+	calendars, err := cc.FindCalendars(ctx, homeSet)
+	if err != nil {
+		return "", fmt.Errorf("failed to retrieve calendars: %w", err)
+	}
+
+	for _, cal := range calendars {
+		if cal.Name == calendarName {
+			return cal.Path, nil
+		}
+	}
+
+	return "", fmt.Errorf("calendar with name %s not found", calendarName)
+}
+
+// Load a configuration file
+func Load(configFile string) (*Config, error) {
+	cfg := new(Config)
+
+	f, err := os.Open(configFile)
+	if err != nil {
+		return nil, fmt.Errorf("failed to open config file %s: %w", configFile, err)
+	}
+
+	defer f.Close()
+
+	if err = yaml.NewDecoder(f).Decode(cfg); err != nil {
+		return nil, fmt.Errorf("failed to decode config file %s: %w", configFile, err)
+	}
+
+	return cfg, nil
+}

go.mod

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+module git.cycore.io/scm/gcal-sync
+
+go 1.22.7
+
+require (
+	github.com/emersion/go-ical v0.0.0-20240127095438-fc1c9d8fb2b6
+	github.com/emersion/go-webdav v0.5.0
+	gopkg.in/yaml.v3 v3.0.1
+)
+
+require github.com/teambition/rrule-go v1.8.2 // indirect

go.sum

@@ -0,0 +1,13 @@
+github.com/emersion/go-ical v0.0.0-20220601085725-0864dccc089f/go.mod h1:2MKFUgfNMULRxqZkadG1Vh44we3y5gJAtTBlVsx1BKQ=
+github.com/emersion/go-ical v0.0.0-20240127095438-fc1c9d8fb2b6 h1:kHoSgklT8weIDl6R6xFpBJ5IioRdBU1v2X2aCZRVCcM=
+github.com/emersion/go-ical v0.0.0-20240127095438-fc1c9d8fb2b6/go.mod h1:BEksegNspIkjCQfmzWgsgbu6KdeJ/4LwUZs7DMBzjzw=
+github.com/emersion/go-vcard v0.0.0-20230815062825-8fda7d206ec9/go.mod h1:HMJKR5wlh/ziNp+sHEDV2ltblO4JD2+IdDOWtGcQBTM=
+github.com/emersion/go-webdav v0.5.0 h1:Ak/BQLgAihJt/UxJbCsEXDPxS5Uw4nZzgIMOq3rkKjc=
+github.com/emersion/go-webdav v0.5.0/go.mod h1:ycyIzTelG5pHln4t+Y32/zBvmrM7+mV7x+V+Gx4ZQno=
+github.com/teambition/rrule-go v1.7.2/go.mod h1:mBJ1Ht5uboJ6jexKdNUJg2NcwP8uUMNvStWXlJD3MvU=
+github.com/teambition/rrule-go v1.8.2 h1:lIjpjvWTj9fFUZCmuoVDrKVOtdiyzbzc93qTmRVe/J8=
+github.com/teambition/rrule-go v1.8.2/go.mod h1:Ieq5AbrKGciP1V//Wq8ktsTXwSwJHDD5mD/wLBGl3p4=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405 h1:yhCVgyC4o1eVCa2tZl7eS0r+SDo693bJlVdllGtEeKM=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=
+gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=

main.go

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+package main
+
+import (
+	"context"
+	"errors"
+	"flag"
+	"log"
+	"log/slog"
+	"time"
+
+	"git.cycore.io/scm/gcal-sync/config"
+)
+
+var configFile string
+var debug bool
+var interval time.Duration
+
+func init() {
+	flag.StringVar(&configFile, "config", "/etc/gcal-sync/config.yaml", "name of the file from which to load the configuration")
+	flag.BoolVar(&debug, "debug", false, "enable debug logging")
+	flag.DurationVar(&interval, "interval", 5*time.Minute, "refresh frequency")
+}
+
+func main() {
+	ctx := context.Background()
+
+	flag.Parse()
+
+	if debug {
+		slog.SetLogLoggerLevel(slog.LevelDebug)
+	} else {
+		slog.SetLogLoggerLevel(slog.LevelInfo)
+	}
+
+	cfg, err := config.Load(configFile)
+	if err != nil {
+		log.Fatalf("failed to load configuration file %s: %s", configFile, err.Error())
+	}
+
+	var failures error
+
+	for _, item := range cfg.Calendars {
+		if err := item.Sync(ctx, cfg); err != nil {
+			slog.Error("failed to sync calendar",
+				slog.String("name", item.Name),
+				slog.String("error", err.Error()),
+			)
+
+			failures = errors.Join(failures, err)
+
+			continue
+		}
+
+		slog.Debug("posted updated calendar data",
+			slog.String("name", item.Name),
+		)
+	}
+
+	for {
+		if err := Sync(ctx, cfg); err != nil {
+			slog.Warn("failed to sync all calendars")
+		} else {
+			slog.Info("synchronized all calendar data",
+				slog.Int("count", len(cfg.Calendars)),
+			)
+		}
+
+		time.Sleep(interval)
+	}
+}
+
+func Sync(ctx context.Context, cfg *config.Config) error {
+	var failures error
+
+	for _, item := range cfg.Calendars {
+		if err := item.Sync(ctx, cfg); err != nil {
+			slog.Error("failed to sync calendar",
+				slog.String("name", item.Name),
+				slog.String("url", item.URL),
+				slog.String("error", err.Error()),
+			)
+
+			failures = errors.Join(failures, err)
+
+			continue
+		}
+
+		slog.Debug("posted updated calendar data",
+			slog.String("name", item.Name),
+		)
+	}
+
+	return failures
+}