feat: improve base URL configuration

githubapp/caching_client_creator.go

@@ -31,9 +31,13 @@ const (
 // NewDefaultCachingClientCreator returns a ClientCreator using values from the
 // configuration or other defaults.
 func NewDefaultCachingClientCreator(c Config, opts ...ClientOption) (ClientCreator, error) {
+	urls, err := c.GetURLs()
+	if err != nil {
+		return nil, err
+	}
 	delegate := NewClientCreator(
-		c.V3APIURL,
-		c.V4APIURL,
+		urls.APIv3.String(),
+		urls.APIv4.String(),
 		c.App.IntegrationID,
 		[]byte(c.App.PrivateKey),
 		opts...,

githubapp/config.go

@@ -15,11 +15,15 @@
 package githubapp
 
 import (
+	"net/url"
 	"os"
 	"strconv"
 )
 
 type Config struct {
+	// BaseURL is a convenience field that sets Web, V3APIURL, and V4APIURL
+	// automatically via ParseURLs. Explicit URL fields take precedence.
+	BaseURL  string `yaml:"base_url" json:"baseUrl"`
 	WebURL   string `yaml:"web_url" json:"webUrl"`
 	V3APIURL string `yaml:"v3_api_url" json:"v3ApiUrl"`
 	V4APIURL string `yaml:"v4_api_url" json:"v4ApiUrl"`
@@ -36,10 +40,10 @@ type Config struct {
 	} `yaml:"oauth" json:"oauth"`
 }
 
-// SetValuesFromEnv sets values in the configuration from coresponding
-// environment variables, if they exist. The optional prefix is added to the
-// start of the environment variable names.
+// SetValuesFromEnv sets configuration values from environment variables.
+// The optional prefix is prepended to each variable name.
 func (c *Config) SetValuesFromEnv(prefix string) {
+	setStringFromEnv("GITHUB_BASE_URL", prefix, &c.BaseURL)
 	setStringFromEnv("GITHUB_WEB_URL", prefix, &c.WebURL)
 	setStringFromEnv("GITHUB_V3_API_URL", prefix, &c.V3APIURL)
 	setStringFromEnv("GITHUB_V4_API_URL", prefix, &c.V4APIURL)
@@ -52,6 +56,59 @@ func (c *Config) SetValuesFromEnv(prefix string) {
 	setStringFromEnv("GITHUB_OAUTH_CLIENT_SECRET", prefix, &c.OAuth.ClientSecret)
 }
 
+// GetURLs resolves the GitHub endpoint URLs for this configuration.
+// Explicit URL fields (WebURL, V3APIURL, V4APIURL) take precedence over
+// BaseURL. If none are set, it falls back to ParseURLs("github.com").
+func (c *Config) GetURLs() (*URLs, error) {
+	// all three explicit URLs are set — use them directly
+	if c.WebURL != "" && c.V3APIURL != "" && c.V4APIURL != "" {
+		return parseExplicitURLs(c.WebURL, c.V3APIURL, c.V4APIURL)
+	}
+
+	// derive from BaseURL, then overlay any explicit overrides
+	base := c.BaseURL
+	if base == "" {
+		base = githubPublicHost
+	}
+	urls, err := ParseURLs(base)
+	if err != nil {
+		return nil, err
+	}
+
+	if c.WebURL != "" {
+		if urls.Web, err = url.Parse(c.WebURL); err != nil {
+			return nil, err
+		}
+	}
+	if c.V3APIURL != "" {
+		if urls.APIv3, err = url.Parse(c.V3APIURL); err != nil {
+			return nil, err
+		}
+	}
+	if c.V4APIURL != "" {
+		if urls.APIv4, err = url.Parse(c.V4APIURL); err != nil {
+			return nil, err
+		}
+	}
+	return urls, nil
+}
+
+func parseExplicitURLs(web, v3, v4 string) (*URLs, error) {
+	wu, err := url.Parse(web)
+	if err != nil {
+		return nil, err
+	}
+	v3u, err := url.Parse(v3)
+	if err != nil {
+		return nil, err
+	}
+	v4u, err := url.Parse(v4)
+	if err != nil {
+		return nil, err
+	}
+	return &URLs{Web: wu, APIv3: v3u, APIv4: v4u}, nil
+}
+
 func setStringFromEnv(key, prefix string, value *string) {
 	if v, ok := os.LookupEnv(prefix + key); ok {
 		*value = v

githubapp/urls.go

@@ -0,0 +1,87 @@
+// Copyright 2024 Palantir Technologies, 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 githubapp
+
+import (
+	"fmt"
+	"net/url"
+	"strings"
+)
+
+const (
+	githubPublicHost = "github.com"
+
+	githubPublicV3URL  = "https://api.github.com/"
+	githubPublicV4URL  = "https://api.github.com/graphql"
+	githubPublicWebURL = "https://github.com"
+)
+
+// URLs holds the resolved endpoint URLs for a GitHub deployment.
+type URLs struct {
+	Web   *url.URL
+	APIv3 *url.URL
+	APIv4 *url.URL
+}
+
+// ParseURLs resolves all GitHub endpoint URLs from a single base URL.
+// For github.com it returns the known public API endpoints; for any other
+// host it constructs the standard GitHub Enterprise Server paths.
+func ParseURLs(baseURL string) (*URLs, error) {
+	if baseURL == "" {
+		return nil, fmt.Errorf("githubapp: base URL must not be empty")
+	}
+
+	// normalize: add scheme if missing so url.Parse works reliably
+	if !strings.Contains(baseURL, "://") {
+		baseURL = "https://" + baseURL
+	}
+
+	u, err := url.Parse(baseURL)
+	if err != nil {
+		return nil, fmt.Errorf("githubapp: invalid base URL %q: %w", baseURL, err)
+	}
+
+	host := strings.ToLower(u.Hostname())
+	if host == githubPublicHost {
+		return publicURLs()
+	}
+	return enterpriseURLs(u)
+}
+
+func publicURLs() (*URLs, error) {
+	web, _ := url.Parse(githubPublicWebURL)
+	v3, _ := url.Parse(githubPublicV3URL)
+	v4, _ := url.Parse(githubPublicV4URL)
+	return &URLs{Web: web, APIv3: v3, APIv4: v4}, nil
+}
+
+func enterpriseURLs(base *url.URL) (*URLs, error) {
+	// strip any path so we build from the root of the host
+	root := &url.URL{Scheme: base.Scheme, Host: base.Host}
+
+	v3, err := root.Parse("api/v3/")
+	if err != nil {
+		return nil, fmt.Errorf("githubapp: could not construct v3 API URL: %w", err)
+	}
+
+	v4, err := root.Parse("api/graphql")
+	if err != nil {
+		return nil, fmt.Errorf("githubapp: could not construct v4 API URL: %w", err)
+	}
+
+	web := &url.URL{Scheme: root.Scheme, Host: root.Host, Path: "/"}
+
+	return &URLs{Web: web, APIv3: v3, APIv4: v4}, nil
+}

githubapp/urls_test.go

@@ -0,0 +1,152 @@
+// Copyright 2024 Palantir Technologies, 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 githubapp
+
+import (
+	"testing"
+)
+
+func TestParseURLs(t *testing.T) {
+	tests := map[string]struct {
+		input   string
+		wantWeb string
+		wantV3  string
+		wantV4  string
+		wantErr bool
+	}{
+		"publicDomain": {
+			input:   "github.com",
+			wantWeb: "https://github.com",
+			wantV3:  "https://api.github.com/",
+			wantV4:  "https://api.github.com/graphql",
+		},
+		"publicHTTPS": {
+			input:   "https://github.com",
+			wantWeb: "https://github.com",
+			wantV3:  "https://api.github.com/",
+			wantV4:  "https://api.github.com/graphql",
+		},
+		"enterprise": {
+			input:   "https://github.example.com",
+			wantWeb: "https://github.example.com/",
+			wantV3:  "https://github.example.com/api/v3/",
+			wantV4:  "https://github.example.com/api/graphql",
+		},
+		"enterpriseNoScheme": {
+			input:   "github.example.com",
+			wantWeb: "https://github.example.com/",
+			wantV3:  "https://github.example.com/api/v3/",
+			wantV4:  "https://github.example.com/api/graphql",
+		},
+		"enterpriseWithPath": {
+			input:   "https://github.example.com/some/path",
+			wantWeb: "https://github.example.com/",
+			wantV3:  "https://github.example.com/api/v3/",
+			wantV4:  "https://github.example.com/api/graphql",
+		},
+		"empty": {
+			input:   "",
+			wantErr: true,
+		},
+	}
+
+	for name, tt := range tests {
+		t.Run(name, func(t *testing.T) {
+			got, err := ParseURLs(tt.input)
+			if tt.wantErr {
+				if err == nil {
+					t.Fatal("expected error, got nil")
+				}
+				return
+			}
+			if err != nil {
+				t.Fatalf("unexpected error: %v", err)
+			}
+			if got.Web.String() != tt.wantWeb {
+				t.Errorf("Web: got %q, want %q", got.Web, tt.wantWeb)
+			}
+			if got.APIv3.String() != tt.wantV3 {
+				t.Errorf("APIv3: got %q, want %q", got.APIv3, tt.wantV3)
+			}
+			if got.APIv4.String() != tt.wantV4 {
+				t.Errorf("APIv4: got %q, want %q", got.APIv4, tt.wantV4)
+			}
+		})
+	}
+}
+
+func TestConfigGetURLs(t *testing.T) {
+	tests := map[string]struct {
+		config  Config
+		wantV3  string
+		wantV4  string
+		wantErr bool
+	}{
+		"baseURLPublic": {
+			config: Config{BaseURL: "github.com"},
+			wantV3: "https://api.github.com/",
+			wantV4: "https://api.github.com/graphql",
+		},
+		"baseURLEnterprise": {
+			config: Config{BaseURL: "https://github.example.com"},
+			wantV3: "https://github.example.com/api/v3/",
+			wantV4: "https://github.example.com/api/graphql",
+		},
+		"explicitURLsOverrideBase": {
+			config: Config{
+				BaseURL:  "https://github.example.com",
+				V3APIURL: "https://github.example.com/api/v3/",
+				V4APIURL: "https://github.example.com/api/graphql",
+				WebURL:   "https://github.example.com",
+			},
+			wantV3: "https://github.example.com/api/v3/",
+			wantV4: "https://github.example.com/api/graphql",
+		},
+		"noFieldsDefaultsToPublic": {
+			config: Config{},
+			wantV3: "https://api.github.com/",
+			wantV4: "https://api.github.com/graphql",
+		},
+		"partialOverride": {
+			config: Config{
+				BaseURL:  "https://github.example.com",
+				V3APIURL: "https://custom.example.com/api/v3/",
+			},
+			wantV3: "https://custom.example.com/api/v3/",
+			wantV4: "https://github.example.com/api/graphql",
+		},
+	}
+
+	for name, tt := range tests {
+		t.Run(name, func(t *testing.T) {
+			got, err := tt.config.GetURLs()
+			if tt.wantErr {
+				if err == nil {
+					t.Fatal("expected error, got nil")
+				}
+				return
+			}
+			if err != nil {
+				t.Fatalf("unexpected error: %v", err)
+			}
+			if got.APIv3.String() != tt.wantV3 {
+				t.Errorf("APIv3: got %q, want %q", got.APIv3, tt.wantV3)
+			}
+			if got.APIv4.String() != tt.wantV4 {
+				t.Errorf("APIv4: got %q, want %q", got.APIv4, tt.wantV4)
+			}
+		})
+	}
+}