github.go

/*
Copyright 2018 The Kubernetes Authors.

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/

package flagutil

import (
	"crypto/rsa"
	"errors"
	"flag"
	"fmt"
	"net/url"
	"strconv"
	"strings"
	"time"

	"github.com/dgrijalva/jwt-go/v4"
	"github.com/sirupsen/logrus"
	utilerrors "k8s.io/apimachinery/pkg/util/errors"

	"k8s.io/test-infra/prow/config/secret"
	gitv2 "k8s.io/test-infra/prow/git/v2"
	"k8s.io/test-infra/prow/github"
)

// GitHubOptions holds options for interacting with GitHub.
//
// Set AllowAnonymous to be true if you want to allow anonymous github access.
// Set AllowDirectAccess to be true if you want to suppress warnings on direct github access (without ghproxy).
type GitHubOptions struct {
	Host              string
	endpoint          Strings
	graphqlEndpoint   string
	TokenPath         string
	AllowAnonymous    bool
	AllowDirectAccess bool
	AppID             string
	AppPrivateKeyPath string

	ThrottleHourlyTokens int
	ThrottleAllowBurst   int

	OrgThrottlers       Strings
	parsedOrgThrottlers map[string]throttlerSettings

	// These will only be set after a github client was retrieved for the first time
	tokenGenerator github.TokenGenerator
	userGenerator  github.UserGenerator

	// the following options determine how the client behaves around retries
	maxRequestTime time.Duration
	maxRetries     int
	max404Retries  int
	initialDelay   time.Duration
	maxSleepTime   time.Duration
}

type throttlerSettings struct {
	hourlyTokens int
	burst        int
}

// flagParams struct is used indirectly by users of this package to customize
// the common flags behavior, such as providing their own default values
// or suppressing presence of certain flags.
type flagParams struct {
	defaults GitHubOptions

	disableThrottlerOptions bool
}

type FlagParameter func(options *flagParams)

// ThrottlerDefaults allows to customize the default values of flags
// that control the throttler behavior. Setting `hourlyTokens` to zero
// disables throttling by default.
func ThrottlerDefaults(hourlyTokens, allowedBursts int) FlagParameter {
	return func(o *flagParams) {
		o.defaults.ThrottleHourlyTokens = hourlyTokens
		o.defaults.ThrottleAllowBurst = allowedBursts
	}
}

// DisableThrottlerOptions suppresses the presence of throttler-related flags,
// effectively disallowing external users to parametrize default throttling
// behavior. This is useful mostly when a program creates multiple GH clients
// with different behavior.
func DisableThrottlerOptions() FlagParameter {
	return func(o *flagParams) {
		o.disableThrottlerOptions = true
	}
}

// AddCustomizedFlags injects GitHub options into the given FlagSet. Behavior can be customized
// via the functional options.
func (o *GitHubOptions) AddCustomizedFlags(fs *flag.FlagSet, paramFuncs ...FlagParameter) {
	o.addFlags(fs, paramFuncs...)
}

// AddFlags injects GitHub options into the given FlagSet
func (o *GitHubOptions) AddFlags(fs *flag.FlagSet) {
	o.addFlags(fs)
}

func (o *GitHubOptions) addFlags(fs *flag.FlagSet, paramFuncs ...FlagParameter) {
	params := flagParams{
		defaults: GitHubOptions{
			Host:            github.DefaultHost,
			endpoint:        NewStrings(github.DefaultAPIEndpoint),
			graphqlEndpoint: github.DefaultGraphQLEndpoint,
		},
	}

	for _, parametrize := range paramFuncs {
		parametrize(&params)
	}

	defaults := params.defaults
	fs.StringVar(&o.Host, "github-host", defaults.Host, "GitHub's default host (may differ for enterprise)")
	o.endpoint = NewStrings(defaults.endpoint.Strings()...)
	fs.Var(&o.endpoint, "github-endpoint", "GitHub's API endpoint (may differ for enterprise).")
	fs.StringVar(&o.graphqlEndpoint, "github-graphql-endpoint", defaults.graphqlEndpoint, "GitHub GraphQL API endpoint (may differ for enterprise).")
	fs.StringVar(&o.TokenPath, "github-token-path", defaults.TokenPath, "Path to the file containing the GitHub OAuth secret.")
	fs.StringVar(&o.AppID, "github-app-id", defaults.AppID, "ID of the GitHub app. If set, requires --github-app-private-key-path to be set and --github-token-path to be unset.")
	fs.StringVar(&o.AppPrivateKeyPath, "github-app-private-key-path", defaults.AppPrivateKeyPath, "Path to the private key of the github app. If set, requires --github-app-id to bet set and --github-token-path to be unset")

	if !params.disableThrottlerOptions {
		fs.IntVar(&o.ThrottleHourlyTokens, "github-hourly-tokens", defaults.ThrottleHourlyTokens, "If set to a value larger than zero, enable client-side throttling to limit hourly token consumption. If set, --github-allowed-burst must be positive too.")
		fs.IntVar(&o.ThrottleAllowBurst, "github-allowed-burst", defaults.ThrottleAllowBurst, "Size of token consumption bursts. If set, --github-hourly-tokens must be positive too and set to a higher or equal number.")
		fs.Var(&o.OrgThrottlers, "github-throttle-org", "Throttler settings for a specific org in org:hourlyTokens:burst format. Can be passed multiple times. Only valid when using github apps auth.")
	}

	fs.DurationVar(&o.maxRequestTime, "github-client.request-timeout", github.DefaultMaxSleepTime, "Timeout for any single request to the GitHub API.")
	fs.IntVar(&o.maxRetries, "github-client.max-retries", github.DefaultMaxRetries, "Maximum number of retries that will be used for a failing request to the GitHub API.")
	fs.IntVar(&o.max404Retries, "github-client.max-404-retries", github.DefaultMax404Retries, "Maximum number of retries that will be used for a 404-ing request to the GitHub API.")
	fs.DurationVar(&o.maxSleepTime, "github-client.backoff-timeout", github.DefaultMaxSleepTime, "Largest allowable Retry-After time for requests to the GitHub API.")
	fs.DurationVar(&o.initialDelay, "github-client.initial-delay", github.DefaultInitialDelay, "Initial delay before retries begin for requests to the GitHub API.")
}

func (o *GitHubOptions) parseOrgThrottlers() error {
	if len(o.OrgThrottlers.vals) == 0 {
		return nil
	}

	if o.AppID == "" {
		return errors.New("--github-throttle-org was passed, but client doesn't use apps auth")
	}

	o.parsedOrgThrottlers = make(map[string]throttlerSettings, len(o.OrgThrottlers.vals))
	var errs []error
	for _, orgThrottler := range o.OrgThrottlers.vals {
		colonSplit := strings.Split(orgThrottler, ":")
		if len(colonSplit) != 3 {
			errs = append(errs, fmt.Errorf("-github-throttle-org=%s is not in org:hourlyTokens:burst format", orgThrottler))
			continue
		}
		org, hourlyTokensString, burstString := colonSplit[0], colonSplit[1], colonSplit[2]
		hourlyTokens, err := strconv.ParseInt(hourlyTokensString, 10, 32)
		if err != nil {
			errs = append(errs, fmt.Errorf("-github-throttle-org=%s is not in org:hourlyTokens:burst format: hourlyTokens is not an int", orgThrottler))
			continue
		}
		burst, err := strconv.ParseInt(burstString, 10, 32)
		if err != nil {
			errs = append(errs, fmt.Errorf("-github-throttle-org=%s is not in org:hourlyTokens:burst format: burst is not an int", orgThrottler))
			continue
		}
		if hourlyTokens < 1 {
			errs = append(errs, fmt.Errorf("-github-throttle-org=%s: hourlyTokens must be > 0", orgThrottler))
			continue
		}
		if burst < 1 {
			errs = append(errs, fmt.Errorf("-github-throttle-org=%s: burst must be > 0", orgThrottler))
			continue
		}
		if burst > hourlyTokens {
			errs = append(errs, fmt.Errorf("-github-throttle-org=%s: burst must not be greater than hourlyTokens", orgThrottler))
			continue
		}
		if _, alreadyExists := o.parsedOrgThrottlers[org]; alreadyExists {
			errs = append(errs, fmt.Errorf("got multiple -github-throttle-org for the %s org", org))
			continue
		}
		o.parsedOrgThrottlers[org] = throttlerSettings{hourlyTokens: int(hourlyTokens), burst: int(burst)}
	}

	return utilerrors.NewAggregate(errs)
}

// Validate validates GitHub options. Note that validate updates the GitHubOptions
// to add default values for TokenPath and graphqlEndpoint.
func (o *GitHubOptions) Validate(bool) error {
	endpoints := o.endpoint.Strings()
	for i, uri := range endpoints {
		if uri == "" {
			endpoints[i] = github.DefaultAPIEndpoint
		} else if _, err := url.ParseRequestURI(uri); err != nil {
			return fmt.Errorf("invalid -github-endpoint URI: %q", uri)
		}
	}

	if o.TokenPath != "" && (o.AppID != "" || o.AppPrivateKeyPath != "") {
		return fmt.Errorf("--token-path is mutually exclusive with --app-id and --app-private-key-path")
	}
	if o.AppID == "" != (o.AppPrivateKeyPath == "") {
		return errors.New("--app-id and --app-private-key-path must be set together")
	}

	if o.TokenPath != "" && len(endpoints) == 1 && endpoints[0] == github.DefaultAPIEndpoint && !o.AllowDirectAccess {
		logrus.Warn("It doesn't look like you are using ghproxy to cache API calls to GitHub! This has become a required component of Prow and other components will soon be allowed to add features that may rapidly consume API ratelimit without caching. Starting May 1, 2020 use Prow components without ghproxy at your own risk! https://github.com/kubernetes/test-infra/tree/master/ghproxy#ghproxy")
	}

	if o.graphqlEndpoint == "" {
		o.graphqlEndpoint = github.DefaultGraphQLEndpoint
	} else if _, err := url.Parse(o.graphqlEndpoint); err != nil {
		return fmt.Errorf("invalid -github-graphql-endpoint URI: %q", o.graphqlEndpoint)
	}

	if (o.ThrottleHourlyTokens > 0) != (o.ThrottleAllowBurst > 0) {
		if o.ThrottleHourlyTokens == 0 {
			// Tolerate `--github-hourly-tokens=0` alone to disable throttling
			o.ThrottleAllowBurst = 0
		} else {
			return errors.New("--github-hourly-tokens and --github-allowed-burst must be either both higher than zero or both equal to zero")
		}
	}
	if o.ThrottleAllowBurst > o.ThrottleHourlyTokens {
		return errors.New("--github-allowed-burst must not be larger than --github-hourly-tokens")
	}

	return o.parseOrgThrottlers()
}

// GitHubClientWithLogFields returns a GitHub client with extra logging fields
func (o *GitHubOptions) GitHubClientWithLogFields(dryRun bool, fields logrus.Fields) (github.Client, error) {
	client, err := o.githubClient(dryRun)
	if err != nil {
		return nil, err
	}
	return client.WithFields(fields), nil
}

func (o *GitHubOptions) githubClient(dryRun bool) (github.Client, error) {
	fields := logrus.Fields{}
	options := o.baseClientOptions()
	options.DryRun = dryRun

	if o.TokenPath == "" && o.AppPrivateKeyPath == "" {
		logrus.Warn("empty -github-token-path, will use anonymous github client")
	}

	if o.TokenPath == "" {
		options.GetToken = func() []byte {
			return []byte{}
		}
	} else {
		if err := secret.Add(o.TokenPath); err != nil {
			return nil, fmt.Errorf("failed to add GitHub token to secret agent: %w", err)
		}
		options.GetToken = secret.GetTokenGenerator(o.TokenPath)
	}

	if o.AppPrivateKeyPath != "" {
		apk, err := o.appPrivateKeyGenerator()
		if err != nil {
			return nil, err
		}
		options.AppPrivateKey = apk
	}

	optionallyThrottled := func(c github.Client) (github.Client, error) {
		// Throttle handles zeros as "disable throttling" so we do not need to call it conditionally
		if err := c.Throttle(o.ThrottleHourlyTokens, o.ThrottleAllowBurst); err != nil {
			return nil, fmt.Errorf("failed to throttle: %w", err)
		}
		for org, settings := range o.parsedOrgThrottlers {
			if err := c.Throttle(settings.hourlyTokens, settings.burst, org); err != nil {
				return nil, fmt.Errorf("failed to set up throttling for org %s: %w", org, err)
			}
		}
		return c, nil
	}

	tokenGenerator, userGenerator, client, err := github.NewClientFromOptions(fields, options)
	if err != nil {
		return nil, fmt.Errorf("failed to construct github client: %w", err)
	}
	o.tokenGenerator = tokenGenerator
	o.userGenerator = userGenerator
	return optionallyThrottled(client)
}

// baseClientOptions populates client options that are derived from flags without processing
func (o *GitHubOptions) baseClientOptions() github.ClientOptions {
	return github.ClientOptions{
		Censor:          secret.Censor,
		AppID:           o.AppID,
		GraphqlEndpoint: o.graphqlEndpoint,
		Bases:           o.endpoint.Strings(),
		MaxRequestTime:  o.maxRequestTime,
		InitialDelay:    o.initialDelay,
		MaxSleepTime:    o.maxSleepTime,
		MaxRetries:      o.maxRetries,
		Max404Retries:   o.max404Retries,
	}
}

// GitHubClient returns a GitHub client.
func (o *GitHubOptions) GitHubClient(dryRun bool) (github.Client, error) {
	return o.GitHubClientWithLogFields(dryRun, logrus.Fields{})
}

// GitHubClientWithAccessToken creates a GitHub client from an access token.
func (o *GitHubOptions) GitHubClientWithAccessToken(token string) (github.Client, error) {
	options := o.baseClientOptions()
	options.GetToken = func() []byte { return []byte(token) }
	options.AppID = "" // Since we are using a token, we should not use the app auth
	_, _, client, err := github.NewClientFromOptions(logrus.Fields{}, options)
	return client, err
}

// GitClientFactory returns git.ClientFactory. Passing non-empty cookieFilePath
// will result in git ClientFactory to work with Gerrit.
// TODO(chaodaiG): move this logic to somewhere more appropriate instead of in
// github.go.
func (o *GitHubOptions) GitClientFactory(cookieFilePath string, cacheDir *string, dryRun, persistCache bool) (gitv2.ClientFactory, error) {
	opts := gitv2.ClientFactoryOpts{
		Censor:         secret.Censor,
		CookieFilePath: cookieFilePath,
		Host:           o.Host,
		Persist:        &persistCache,
	}
	if cacheDir != nil && *cacheDir != "" {
		opts.CacheDirBase = cacheDir
	}

	if cookieFilePath == "" && (o.TokenPath != "" || o.AppPrivateKeyPath != "") {
		// Make a client with auth suitable for GitHub
		user, generator, err := o.getGitHubAuthentication(dryRun)
		if err != nil {
			return nil, fmt.Errorf("failed to get git authentication: %w", err)
		}
		opts.Username = func() (string, error) { return user, nil }
		opts.Token = generator
	}
	// If the client is for Gerrit we're already set with the cookie filepath.

	gitClientFactory, err := gitv2.NewClientFactory(opts.Apply)
	if err != nil {
		return nil, fmt.Errorf("failed to create git client factory: %w", err)
	}
	return gitClientFactory, nil
}

func (o *GitHubOptions) getGitHubAuthentication(dryRun bool) (string, gitv2.TokenGetter, error) {
	// the client must have been created at least once for us to have generators
	if o.userGenerator == nil {
		if _, err := o.GitHubClient(dryRun); err != nil {
			return "", nil, fmt.Errorf("error getting GitHub client: %w", err)
		}
	}

	login, err := o.userGenerator()
	if err != nil {
		return "", nil, fmt.Errorf("error getting bot name: %w", err)
	}
	return login, gitv2.TokenGetter(o.tokenGenerator), nil
}

func (o *GitHubOptions) appPrivateKeyGenerator() (func() *rsa.PrivateKey, error) {
	generator, err := secret.AddWithParser(
		o.AppPrivateKeyPath,
		func(raw []byte) (*rsa.PrivateKey, error) {
			privateKey, err := jwt.ParseRSAPrivateKeyFromPEM(raw)
			if err != nil {
				return nil, fmt.Errorf("failed to parse rsa key from pem: %w", err)
			}
			return privateKey, nil
		},
	)
	if err != nil {
		return nil, fmt.Errorf("failed to add the key from --app-private-key-path to secret agent: %w", err)
	}

	return generator, nil
}