[exporter/datadog] add basic API key validation on startup

.chloggen/dd-config-api-key-fix.yaml

@@ -0,0 +1,28 @@
+# Use this changelog template to create an entry for release notes.
+
+# One of 'breaking', 'deprecation', 'new_component', 'enhancement', 'bug_fix'
+change_type: bug_fix
+
+# The name of the component, or a single word describing the area of concern, (e.g. filelogreceiver)
+component: connector/datadog, exporter/datadog, pkg/datadog
+
+# A brief description of the change.  Surround your text with quotes ("") if it needs to start with a backtick (`).
+note: strip extra quotations from API keys when read in via environment variables
+
+# Mandatory: One or more tracking issues related to the change. You can use the PR number here if no issue exists.
+issues: [36509]
+
+# (Optional) One or more lines of additional information to render under the primary note.
+# These lines will be padded with 2 spaces and then inserted directly into the document.
+# Use pipe (|) for multiline entries.
+subtext: |
+  API keys should still validate even if reading in via environment variable caused extra quotations.
+
+# If your change doesn't affect end users or the exported elements of any package,
+# you should instead start your pull request title with [chore] or use the "Skip Changelog" label.
+# Optional: The change log or logs in which this entry should be included.
+# e.g. '[user]' or '[user, api]'
+# Include 'user' if the change is relevant to end users.
+# Include 'api' if there is a change to a library API.
+# Default: '[user]'
+change_logs: [user]

pkg/datadog/config/config.go

@@ -120,7 +120,7 @@ func (c *Config) Validate() error {
 		return fmt.Errorf("hostname field is invalid: %w", err)
 	}
 
-	if c.API.Key == "" {
+	if string(c.API.Key) == "" {
 		return ErrUnsetAPIKey
 	}
 
@@ -250,7 +250,8 @@ func (c *Config) Unmarshal(configMap *confmap.Conf) error {
 	}
 	c.warnings = append(c.warnings, renamingWarnings...)
 
-	c.API.Key = configopaque.String(strings.TrimSpace(string(c.API.Key)))
+	// remove leading/trailing quotation marks to avoid issues with the API key
+	c.API.Key = configopaque.String(strings.Trim(string(c.API.Key), `"'`))
 
 	// If an endpoint is not explicitly set, override it based on the site.
 	if !configMap.IsSet("metrics::endpoint") {

pkg/datadog/config/config_test.go

@@ -185,6 +185,18 @@ func TestValidate(t *testing.T) {
 	}
 }
 
+func TestAPIKeyDoubleQuotes(t *testing.T) {
+	configMap := confmap.NewFromStringMap(map[string]any{
+		"api": map[string]any{
+			"key": "'apikey'",
+		},
+	})
+	cfg := CreateDefaultConfig().(*Config)
+	err := cfg.Unmarshal(configMap)
+	assert.NoError(t, err)
+	assert.Equal(t, "apikey", string(cfg.API.Key))
+}
+
 func TestUnmarshal(t *testing.T) {
 	cfgWithHTTPConfigs := CreateDefaultConfig().(*Config)
 	idleConnTimeout := 30 * time.Second