Refactor credential handling and add tests (#25)

* Refactor credential handling and add tests

* add more cache tests, run tests in pre-commit

* start adding refreshable cred provider tests

* add more refreshable cred provider tests

* explicitly set golang version in pre-commit

* round all the times!

* how about unix timestamps

* add custom time type to fix json unmarshaling

.github/workflows/precommit.yml

@@ -11,4 +11,7 @@ jobs:
     steps:
       - uses: actions/checkout@v2
       - uses: actions/setup-python@v2
+      - uses: actions/setup-go@v2
+        with:
+          go-version: '^1.15.6'
       - uses: pre-commit/action@v2.0.0

.pre-commit-config.yaml

@@ -5,5 +5,5 @@ repos:
     - id: go-fmt
     - id: go-vet
     - id: go-imports
-    - id: no-go-testing
+    - id: go-unit-tests
     - id: go-mod-tidy

cache/cache.go

@@ -0,0 +1,113 @@
+/*
+ * Copyright 2020 Netflix, Inc.
+ *
+ * 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 cache
+
+import (
+	"fmt"
+	"strings"
+	"sync"
+
+	"github.com/netflix/weep/creds"
+	"github.com/netflix/weep/errors"
+	log "github.com/sirupsen/logrus"
+)
+
+var GlobalCache CredentialCache
+
+type CredentialCache struct {
+	RoleCredentials map[string]*creds.RefreshableProvider
+	DefaultRole     string
+	mu              sync.RWMutex
+}
+
+func init() {
+	GlobalCache = CredentialCache{
+		RoleCredentials: make(map[string]*creds.RefreshableProvider),
+	}
+}
+
+// getCacheSlug returns a string unique to a particular combination of a role and chain of roles to assume.
+func getCacheSlug(role string, assume []string) string {
+	elements := append([]string{role}, assume...)
+	return strings.Join(elements, "/")
+}
+
+func (cc *CredentialCache) Get(role string, assumeChain []string) (*creds.RefreshableProvider, error) {
+	log.WithFields(log.Fields{
+		"role":        role,
+		"assumeChain": assumeChain,
+	}).Info("retrieving credentials")
+	c, ok := cc.get(getCacheSlug(role, assumeChain))
+	if ok {
+		log.Debugf("found credentials for %s in cache", role)
+		return c, nil
+	}
+	return nil, errors.NoCredentialsFoundInCache
+}
+
+func (cc *CredentialCache) GetOrSet(client *creds.Client, role, region string, assumeChain []string) (*creds.RefreshableProvider, error) {
+	c, err := cc.Get(role, assumeChain)
+	if err == nil {
+		return c, nil
+	}
+	log.Debugf("no credentials for %s in cache, creating", role)
+
+	c, err = cc.set(client, role, region, assumeChain)
+	if err != nil {
+		return nil, err
+	}
+
+	return c, nil
+}
+
+func (cc *CredentialCache) SetDefault(client *creds.Client, role, region string, assumeChain []string) error {
+	_, err := cc.set(client, role, region, assumeChain)
+	if err != nil {
+		return err
+	}
+	cc.DefaultRole = getCacheSlug(role, assumeChain)
+	return nil
+}
+
+func (cc *CredentialCache) GetDefault() (*creds.RefreshableProvider, error) {
+	if cc.DefaultRole == "" {
+		return nil, errors.NoDefaultRoleSet
+	}
+	c, ok := cc.get(cc.DefaultRole)
+	if ok {
+		return c, nil
+	}
+	return nil, errors.NoCredentialsFoundInCache
+}
+
+func (cc *CredentialCache) get(slug string) (*creds.RefreshableProvider, bool) {
+	cc.mu.RLock()
+	defer cc.mu.RUnlock()
+	c, ok := cc.RoleCredentials[slug]
+	return c, ok
+}
+
+func (cc *CredentialCache) set(client *creds.Client, role, region string, assumeChain []string) (*creds.RefreshableProvider, error) {
+	c, err := creds.NewRefreshableProvider(client, role, region, assumeChain, false)
+	if err != nil {
+		return nil, fmt.Errorf("could not generate creds: %w", err)
+	}
+	cc.mu.Lock()
+	defer cc.mu.Unlock()
+	cc.RoleCredentials[getCacheSlug(role, assumeChain)] = c
+	return c, nil
+}