[proxy] add configcat plugin

Author: mustard-mh

components/proxy/Dockerfile

@@ -18,6 +18,7 @@ RUN xcaddy build v2.5.2 \
   --with github.com/gitpod-io/gitpod/proxy/plugins/secwebsocketkey=/plugins/secwebsocketkey \
   --with github.com/gitpod-io/gitpod/proxy/plugins/workspacedownload=/plugins/workspacedownload \
   --with github.com/gitpod-io/gitpod/proxy/plugins/headlesslogdownload=/plugins/headlesslogdownload \
+  --with github.com/gitpod-io/gitpod/proxy/plugins/configcat=/plugins/configcat \
   --with github.com/gitpod-io/gitpod/proxy/plugins/logif=/plugins/logif \
   --with github.com/gitpod-io/gitpod/proxy/plugins/jsonselect=/plugins/jsonselect \
   --with github.com/gitpod-io/gitpod/proxy/plugins/sshtunnel=/plugins/sshtunnel

components/proxy/conf/Caddyfile

@@ -15,6 +15,7 @@
 	order gitpod.cors_origin            before header
 	order gitpod.workspace_download     before redir
 	order gitpod.headless_log_download	before rewrite
+	order gitpod.configcat	            before rewrite
 	order gitpod.sec_websocket_key      before header
 
 	servers {
@@ -194,6 +195,14 @@ https://{$GITPOD_DOMAIN} {
 		}
 	}
 
+	@configcat path /configcat*
+	handle @configcat {
+		gitpod.cors_origin {
+			any_domain true
+		}
+		gitpod.configcat
+	}
+
 	@backend_wss {
 			path /api/gitpod
 	}

components/proxy/plugins/configcat/configcat.go

@@ -0,0 +1,213 @@
+// Copyright (c) 2022 Gitpod GmbH. All rights reserved.
+// Licensed under the GNU Affero General Public License (AGPL).
+// See License-AGPL.txt in the project root for license information.
+
+package configcat
+
+import (
+	"fmt"
+	"io/ioutil"
+	"net/http"
+	"os"
+	"regexp"
+	"strings"
+	"sync"
+	"time"
+
+	"github.com/caddyserver/caddy/v2"
+	"github.com/caddyserver/caddy/v2/caddyconfig/caddyfile"
+	"github.com/caddyserver/caddy/v2/caddyconfig/httpcaddyfile"
+	"github.com/caddyserver/caddy/v2/modules/caddyhttp"
+	"go.uber.org/zap"
+	"golang.org/x/sync/singleflight"
+)
+
+const (
+	configCatModule = "gitpod.configcat"
+)
+
+var (
+	DefaultConfig = []byte("{}")
+	pathRegex     = regexp.MustCompile(`^/configcat/configuration-files/gitpod/config_v\d+\.json$`)
+)
+
+func init() {
+	caddy.RegisterModule(ConfigCat{})
+	httpcaddyfile.RegisterHandlerDirective(configCatModule, parseCaddyfile)
+}
+
+type configCache struct {
+	data []byte
+	hash string
+}
+
+// ConfigCat implements an configcat config CDN
+type ConfigCat struct {
+	sdkKey string
+	// baseUrl of configcat, default https://cdn-global.configcat.com
+	baseUrl string
+	// pollInterval sets after how much time a configuration is considered stale.
+	pollInterval time.Duration
+
+	configCache map[string]*configCache
+	m           sync.RWMutex
+
+	httpClient *http.Client
+	logger     *zap.Logger
+}
+
+// CaddyModule returns the Caddy module information.
+func (ConfigCat) CaddyModule() caddy.ModuleInfo {
+	return caddy.ModuleInfo{
+		ID:  "http.handlers.gitpod_configcat",
+		New: func() caddy.Module { return new(ConfigCat) },
+	}
+}
+
+// ServeHTTP implements caddyhttp.MiddlewareHandler.
+func (c *ConfigCat) ServeHTTP(w http.ResponseWriter, r *http.Request, next caddyhttp.Handler) error {
+	if !pathRegex.MatchString(r.URL.Path) {
+		return next.ServeHTTP(w, r)
+	}
+	w.Header().Set("Content-Type", "application/json")
+	if c.sdkKey == "" {
+		w.Write(DefaultConfig)
+		return nil
+	}
+	etag := r.Header.Get("If-None-Match")
+	arr := strings.Split(r.URL.Path, "/")
+	configVersion := arr[len(arr)-1]
+	config := c.getConfigWithCache(configVersion)
+	if etag != "" && config.hash == etag {
+		w.WriteHeader(http.StatusNotModified)
+		return nil
+	}
+	if config.hash != "" {
+		w.Header().Set("ETag", config.hash)
+	}
+	w.Write(config.data)
+	return nil
+}
+
+func (c *ConfigCat) Provision(ctx caddy.Context) error {
+	c.logger = ctx.Logger(c)
+	c.configCache = make(map[string]*configCache)
+
+	c.sdkKey = os.Getenv("CONFIGCAT_SDK_KEY")
+	if c.sdkKey == "" {
+		return nil
+	}
+
+	c.httpClient = &http.Client{
+		Timeout: 10 * time.Second,
+	}
+	c.baseUrl = os.Getenv("CONFIGCAT_BASE_URL")
+	if c.baseUrl == "" {
+		c.baseUrl = "https://cdn-global.configcat.com"
+	}
+	dur, err := time.ParseDuration(os.Getenv("CONFIGCAT_POLL_INTERVAL"))
+	if err != nil {
+		c.pollInterval = time.Minute
+		c.logger.Warn("cannot parse poll interval of configcat, default to 1m")
+	} else {
+		c.pollInterval = dur
+	}
+
+	// poll config
+	go func() {
+		for range time.Tick(c.pollInterval) {
+			for version, cache := range c.configCache {
+				c.updateConfigCache(version, cache)
+			}
+		}
+	}()
+	return nil
+}
+
+func (c *ConfigCat) getConfigWithCache(configVersion string) *configCache {
+	c.m.RLock()
+	data := c.configCache[configVersion]
+	c.m.RUnlock()
+	if data != nil {
+		return data
+	}
+	return c.updateConfigCache(configVersion, nil)
+}
+
+func (c *ConfigCat) updateConfigCache(version string, prevConfig *configCache) *configCache {
+	t, err := c.fetchConfigCatConfig(version, prevConfig)
+	if err != nil {
+		return &configCache{
+			data: DefaultConfig,
+			hash: "",
+		}
+	}
+	c.m.Lock()
+	c.configCache[version] = t
+	c.m.Unlock()
+	return t
+}
+
+var sg = &singleflight.Group{}
+
+// fetchConfigCatConfig with different config version. i.e. config_v5.json
+func (c *ConfigCat) fetchConfigCatConfig(version string, prevConfig *configCache) (*configCache, error) {
+	b, err, _ := sg.Do(fmt.Sprintf("fetch_%s", version), func() (interface{}, error) {
+		url := fmt.Sprintf("%s/configuration-files/%s/%s", c.baseUrl, c.sdkKey, version)
+		req, err := http.NewRequest("GET", url, nil)
+		if err != nil {
+			c.logger.With(zap.Error(err)).Error("cannot create request")
+			return nil, err
+		}
+		if prevConfig != nil && prevConfig.hash != "" {
+			req.Header.Add("If-None-Match", prevConfig.hash)
+		}
+		resp, err := c.httpClient.Do(req)
+		if err != nil {
+			c.logger.With(zap.Error(err)).Error("cannot fetch configcat config")
+			return nil, err
+		}
+
+		if resp.StatusCode == 304 {
+			return prevConfig, nil
+		}
+
+		if resp.StatusCode >= 200 && resp.StatusCode < 300 {
+			b, err := ioutil.ReadAll(resp.Body)
+			if err != nil {
+				c.logger.With(zap.Error(err), zap.String("version", version)).Error("cannot read configcat config response")
+				return nil, err
+			}
+			return &configCache{
+				data: b,
+				hash: resp.Header.Get("Etag"),
+			}, nil
+		}
+		return nil, fmt.Errorf("received unexpected response %v", resp.Status)
+	})
+	if err != nil {
+		return nil, err
+	}
+	return b.(*configCache), nil
+}
+
+// UnmarshalCaddyfile implements Caddyfile.Unmarshaler.
+func (m *ConfigCat) UnmarshalCaddyfile(d *caddyfile.Dispenser) error {
+	return nil
+}
+
+func parseCaddyfile(h httpcaddyfile.Helper) (caddyhttp.MiddlewareHandler, error) {
+	m := new(ConfigCat)
+	err := m.UnmarshalCaddyfile(h.Dispenser)
+	if err != nil {
+		return nil, err
+	}
+
+	return m, nil
+}
+
+// Interface guards
+var (
+	_ caddyhttp.MiddlewareHandler = (*ConfigCat)(nil)
+	_ caddyfile.Unmarshaler       = (*ConfigCat)(nil)
+)

components/proxy/plugins/configcat/go.mod

@@ -0,0 +1,112 @@
+module github.com/gitpod-io/gitpod/proxy/plugins/configcat
+
+go 1.18
+
+require (
+	github.com/caddyserver/caddy/v2 v2.5.2
+	go.uber.org/zap v1.21.0
+	golang.org/x/sync v0.0.0-20210220032951-036812b2e83c
+)
+
+require (
+	filippo.io/edwards25519 v1.0.0-rc.1 // indirect
+	github.com/AndreasBriese/bbloom v0.0.0-20190825152654-46b345b51c96 // indirect
+	github.com/Masterminds/goutils v1.1.1 // indirect
+	github.com/Masterminds/semver/v3 v3.1.1 // indirect
+	github.com/Masterminds/sprig/v3 v3.2.2 // indirect
+	github.com/antlr/antlr4/runtime/Go/antlr v0.0.0-20220418222510-f25a4f6275ed // indirect
+	github.com/aryann/difflib v0.0.0-20210328193216-ff5ff6dc229b // indirect
+	github.com/beorn7/perks v1.0.1 // indirect
+	github.com/caddyserver/certmagic v0.16.1 // indirect
+	github.com/cespare/xxhash v1.1.0 // indirect
+	github.com/cespare/xxhash/v2 v2.1.2 // indirect
+	github.com/cheekybits/genny v1.0.0 // indirect
+	github.com/chzyer/readline v0.0.0-20180603132655-2972be24d48e // indirect
+	github.com/cpuguy83/go-md2man/v2 v2.0.0 // indirect
+	github.com/dgraph-io/badger v1.6.2 // indirect
+	github.com/dgraph-io/badger/v2 v2.2007.4 // indirect
+	github.com/dgraph-io/ristretto v0.0.4-0.20200906165740-41ebdbffecfd // indirect
+	github.com/dgryski/go-farm v0.0.0-20200201041132-a6ae2369ad13 // indirect
+	github.com/dustin/go-humanize v1.0.1-0.20200219035652-afde56e7acac // indirect
+	github.com/fsnotify/fsnotify v1.5.1 // indirect
+	github.com/go-kit/kit v0.10.0 // indirect
+	github.com/go-logfmt/logfmt v0.5.0 // indirect
+	github.com/go-sql-driver/mysql v1.6.0 // indirect
+	github.com/go-task/slim-sprig v0.0.0-20210107165309-348f09dbbbc0 // indirect
+	github.com/golang/protobuf v1.5.2 // indirect
+	github.com/golang/snappy v0.0.4 // indirect
+	github.com/google/cel-go v0.11.4 // indirect
+	github.com/google/uuid v1.3.0 // indirect
+	github.com/huandu/xstrings v1.3.2 // indirect
+	github.com/imdario/mergo v0.3.12 // indirect
+	github.com/jackc/chunkreader/v2 v2.0.1 // indirect
+	github.com/jackc/pgconn v1.10.1 // indirect
+	github.com/jackc/pgio v1.0.0 // indirect
+	github.com/jackc/pgpassfile v1.0.0 // indirect
+	github.com/jackc/pgproto3/v2 v2.2.0 // indirect
+	github.com/jackc/pgservicefile v0.0.0-20200714003250-2b9c44734f2b // indirect
+	github.com/jackc/pgtype v1.9.0 // indirect
+	github.com/jackc/pgx/v4 v4.14.0 // indirect
+	github.com/klauspost/compress v1.15.6 // indirect
+	github.com/klauspost/cpuid/v2 v2.0.13 // indirect
+	github.com/libdns/libdns v0.2.1 // indirect
+	github.com/lucas-clemente/quic-go v0.28.0 // indirect
+	github.com/manifoldco/promptui v0.9.0 // indirect
+	github.com/marten-seemann/qpack v0.2.1 // indirect
+	github.com/marten-seemann/qtls-go1-16 v0.1.5 // indirect
+	github.com/marten-seemann/qtls-go1-17 v0.1.2 // indirect
+	github.com/marten-seemann/qtls-go1-18 v0.1.2 // indirect
+	github.com/marten-seemann/qtls-go1-19 v0.1.0-beta.1 // indirect
+	github.com/mattn/go-colorable v0.1.8 // indirect
+	github.com/mattn/go-isatty v0.0.13 // indirect
+	github.com/matttproud/golang_protobuf_extensions v1.0.1 // indirect
+	github.com/mgutz/ansi v0.0.0-20200706080929-d51e80ef957d // indirect
+	github.com/mholt/acmez v1.0.2 // indirect
+	github.com/micromdm/scep/v2 v2.1.0 // indirect
+	github.com/miekg/dns v1.1.46 // indirect
+	github.com/mitchellh/copystructure v1.2.0 // indirect
+	github.com/mitchellh/go-ps v1.0.0 // indirect
+	github.com/mitchellh/reflectwalk v1.0.2 // indirect
+	github.com/nxadm/tail v1.4.8 // indirect
+	github.com/onsi/ginkgo v1.16.4 // indirect
+	github.com/pkg/errors v0.9.1 // indirect
+	github.com/prometheus/client_golang v1.12.1 // indirect
+	github.com/prometheus/client_model v0.2.0 // indirect
+	github.com/prometheus/common v0.32.1 // indirect
+	github.com/prometheus/procfs v0.7.3 // indirect
+	github.com/rs/xid v1.2.1 // indirect
+	github.com/russross/blackfriday/v2 v2.0.1 // indirect
+	github.com/shopspring/decimal v1.2.0 // indirect
+	github.com/shurcooL/sanitized_anchor_name v1.0.0 // indirect
+	github.com/sirupsen/logrus v1.8.1 // indirect
+	github.com/slackhq/nebula v1.5.2 // indirect
+	github.com/smallstep/certificates v0.19.0 // indirect
+	github.com/smallstep/cli v0.18.0 // indirect
+	github.com/smallstep/nosql v0.4.0 // indirect
+	github.com/smallstep/truststore v0.11.0 // indirect
+	github.com/spf13/cast v1.4.1 // indirect
+	github.com/stoewer/go-strcase v1.2.0 // indirect
+	github.com/tailscale/tscert v0.0.0-20220316030059-54bbcb9f74e2 // indirect
+	github.com/urfave/cli v1.22.5 // indirect
+	go.etcd.io/bbolt v1.3.6 // indirect
+	go.mozilla.org/pkcs7 v0.0.0-20210826202110-33d05740a352 // indirect
+	go.step.sm/cli-utils v0.7.0 // indirect
+	go.step.sm/crypto v0.16.1 // indirect
+	go.step.sm/linkedca v0.15.0 // indirect
+	go.uber.org/atomic v1.9.0 // indirect
+	go.uber.org/multierr v1.6.0 // indirect
+	golang.org/x/crypto v0.0.0-20220210151621-f4118a5b28e2 // indirect
+	golang.org/x/mod v0.4.2 // indirect
+	golang.org/x/net v0.0.0-20220624214902-1bab6f366d9e // indirect
+	golang.org/x/sys v0.0.0-20220520151302-bc2c85ada10a // indirect
+	golang.org/x/term v0.0.0-20210927222741-03fcf44c2211 // indirect
+	golang.org/x/text v0.3.8-0.20211004125949-5bd84dd9b33b // indirect
+	golang.org/x/tools v0.1.7 // indirect
+	golang.org/x/xerrors v0.0.0-20200804184101-5ec99f83aff1 // indirect
+	google.golang.org/genproto v0.0.0-20220502173005-c8bf987b8c21 // indirect
+	google.golang.org/grpc v1.46.0 // indirect
+	google.golang.org/protobuf v1.28.0 // indirect
+	gopkg.in/square/go-jose.v2 v2.6.0 // indirect
+	gopkg.in/tomb.v1 v1.0.0-20141024135613-dd632973f1e7 // indirect
+	howett.net/plist v1.0.0 // indirect
+)