Add clientcreatorpool abstraction for utilizing multiple github apps …

…for extra ratelimit (#756)

server/neptune/temporalworker/clientcreatorpool/clientcreatorpool.go

@@ -0,0 +1,80 @@
+package clientcreatorpool
+
+import (
+	"fmt"
+
+	"github.com/palantir/go-githubapp/githubapp"
+	"github.com/pkg/errors"
+	ghClient "github.com/runatlantis/atlantis/server/neptune/workflows/activities/github"
+	"github.com/uber-go/tally/v4"
+)
+
+type ClientCreatorPool struct {
+	// keys are app ids aka integration ids
+	// Note: It would make a lot more sense to use something like a name, or the slug, right?
+	// The reason why that is not the case, is that then we would have to pass those around. We can't
+	// modify the clientCreator (it is part of the githubapp library), and you can see that inside, its
+	// fields are private, and there is no way to associate a given clientCreator with a name. There is
+	// no slug inside the githubapp.Config, only private keys and app ids, and we don't want to use
+	// private keys as keys.
+	idToClientCreator     map[int]githubapp.ClientCreator
+	idToRateLimitRemaning map[int]int
+	// Note that integration id is NOT installation id. Those are 2 separate things.
+}
+
+type ClientCreatorPoolConfig struct {
+	id     int
+	config githubapp.Config
+}
+
+// This function is only called once, when the server starts
+func (c *ClientCreatorPool) Initialize(configs []ClientCreatorPoolConfig, scope tally.Scope) error {
+	c.idToClientCreator = make(map[int]githubapp.ClientCreator)
+	c.idToRateLimitRemaning = make(map[int]int)
+
+	for _, config := range configs {
+		t := fmt.Sprintf("github.app.%d", config.id)
+		clientCreator, err := githubapp.NewDefaultCachingClientCreator(
+			config.config,
+			githubapp.WithClientMiddleware(
+				// combine the id with app
+				ghClient.ClientMetrics(scope.SubScope(t)),
+			))
+		if err != nil {
+			return errors.Wrap(err, "client creator")
+		}
+		c.idToClientCreator[config.id] = clientCreator
+		// For the rate limit remaining, initially needs to be non-zero, the actual rate limit number value will be
+		// updated within 60 seconds by the cron that checks the rate limit
+		c.idToRateLimitRemaning[config.id] = 100
+	}
+
+	return nil
+}
+
+func (c *ClientCreatorPool) GetClientCreatorWithMaxRemainingRateLimit() (githubapp.ClientCreator, error) {
+	maxSeenSoFar := 0
+	theId := 0
+	for id, num := range c.idToRateLimitRemaning {
+		if num > maxSeenSoFar {
+			maxSeenSoFar = num
+			theId = id
+		}
+	}
+
+	clientCreator, ok := c.idToClientCreator[theId]
+	if !ok {
+		return nil, errors.New("client creator not found")
+	}
+
+	return clientCreator, nil
+}
+
+// this func will be used in the crons to update the rate limit remaining
+func (c *ClientCreatorPool) SetRateLimitRemaining(id int, remaining int) {
+	c.idToRateLimitRemaning[id] = remaining
+}
+
+func (c *ClientCreatorPool) GetRateLimitRemaining(id int) int {
+	return c.idToRateLimitRemaning[id]
+}

server/neptune/temporalworker/clientcreatorpool/clientcreatorpool_test.go

@@ -0,0 +1,74 @@
+package clientcreatorpool
+
+import (
+	"testing"
+
+	"github.com/palantir/go-githubapp/githubapp"
+	"github.com/runatlantis/atlantis/server/logging"
+	"github.com/runatlantis/atlantis/server/metrics"
+	"github.com/stretchr/testify/assert"
+)
+
+func initialize(t *testing.T) ClientCreatorPool {
+	configs := []ClientCreatorPoolConfig{
+		{
+			id:     564754,
+			config: githubapp.Config{},
+		},
+		{
+			id:     243643,
+			config: githubapp.Config{},
+		},
+	}
+
+	configs[0].config.App.IntegrationID = 564754
+	configs[0].config.App.PrivateKey = "key1"
+	configs[0].config.App.WebhookSecret = "secret1"
+
+	configs[1].config.App.IntegrationID = 243643
+	configs[1].config.App.PrivateKey = "key2"
+	configs[1].config.App.WebhookSecret = "secret2"
+
+	c := ClientCreatorPool{}
+	ctxLogger := logging.NewNoopCtxLogger(t)
+	scope, _, _ := metrics.NewLoggingScope(ctxLogger, "null")
+	_ = c.Initialize(configs, scope)
+	return c
+}
+
+func TestInitialize(t *testing.T) {
+	configs := []ClientCreatorPoolConfig{
+		{
+			id:     1,
+			config: githubapp.Config{},
+		},
+		{
+			id:     2,
+			config: githubapp.Config{},
+		},
+	}
+
+	configs[0].config.App.IntegrationID = 1
+	configs[0].config.App.PrivateKey = "key1"
+	configs[0].config.App.WebhookSecret = "secret1"
+
+	configs[1].config.App.IntegrationID = 2
+	configs[1].config.App.PrivateKey = "key2"
+	configs[1].config.App.WebhookSecret = "secret2"
+
+	c := ClientCreatorPool{}
+	ctxLogger := logging.NewNoopCtxLogger(t)
+	scope, _, _ := metrics.NewLoggingScope(ctxLogger, "null")
+	err := c.Initialize(configs, scope)
+	assert.NoError(t, err)
+}
+
+func TestGetClientCreatorWithMaxRemainingRateLimit(t *testing.T) {
+	c := initialize(t)
+	c.SetRateLimitRemaining(564754, 9000)
+	clientCreator, err := c.GetClientCreatorWithMaxRemainingRateLimit()
+	assert.NoError(t, err)
+	assert.NotNil(t, clientCreator)
+	assert.Equal(t, clientCreator, c.idToClientCreator[564754])
+	assert.Equal(t, 9000, c.GetRateLimitRemaining(564754))
+}