Merge pull request #7 from lucaong/lazy-signer-instantiation

Initialize signer lazily

CHANGELOG.md

@@ -1,5 +1,7 @@
 ## [Unreleased]
 
+- Allow lazy loading the signer
+
 ## [0.5.4] 2024-11-18
 
 - Allow creating public container

README.md

@@ -95,6 +95,19 @@ client.delete_blob(path)
 
 For the full list of methods: https://www.rubydoc.info/gems/azure-blob/AzureBlob/Client
 
+## options
+
+### Lazy loading
+
+The client is configured to raise an error early for missing credentials, causing it to crash before becoming healthy. This behavior can sometimes be undesirable, such as during assets precompilation.
+
+To enable lazy loading and ignore missing credentials, set the `lazy` option:
+
+`AzureBlob::Client.new(account_name: nil, access_key: nil, container: nil, lazy: true)`
+
+or add `lazy: true` to your `config/storage.yml` for Active Storage.
+
+
 ## Contributing
 
 ### Dev environment

lib/azure_blob/client.rb

@@ -20,18 +20,10 @@ def initialize(account_name:, access_key: nil, principal_id: nil, container:, ho
       @container = container
       @host = host
       @cloud_regions = options[:cloud_regions]&.to_sym || :global
-
-      no_access_key = access_key.nil? || access_key&.empty?
-      using_managed_identities = no_access_key && !principal_id.nil? || options[:use_managed_identities]
-
-      if !using_managed_identities && no_access_key
-        raise AzureBlob::Error.new(
-          "`access_key` cannot be empty. To use managed identities instead, pass a `principal_id` or set `use_managed_identities` to true."
-        )
-      end
-      @signer = using_managed_identities ?
-        AzureBlob::EntraIdSigner.new(account_name:, host: self.host, principal_id:) :
-        AzureBlob::SharedKeySigner.new(account_name:, access_key:, host: self.host)
+      @access_key = access_key
+      @principal_id = principal_id
+      @use_managed_identities = options[:use_managed_identities]
+      signer unless options[:lazy]
     end
 
     # Create a blob of type block. Will automatically split the the blob in multiple block and send the blob in pieces (blocks) if the blob is too big.
@@ -364,6 +356,24 @@ def host
       @host ||= "https://#{account_name}.blob.#{CLOUD_REGIONS_SUFFIX[cloud_regions]}"
     end
 
-    attr_reader :account_name, :signer, :container, :http, :cloud_regions
+    def signer
+      @signer ||=
+        begin
+          no_access_key = access_key.nil? || access_key&.empty?
+          using_managed_identities = no_access_key && !principal_id.nil? || use_managed_identities
+
+          if !using_managed_identities && no_access_key
+            raise AzureBlob::Error.new(
+              "`access_key` cannot be empty. To use managed identities instead, pass a `principal_id` or set `use_managed_identities` to true."
+            )
+          end
+
+          using_managed_identities ?
+            AzureBlob::EntraIdSigner.new(account_name:, host:, principal_id:) :
+            AzureBlob::SharedKeySigner.new(account_name:, access_key:, host:)
+        end
+    end
+
+    attr_reader :account_name, :container, :http, :cloud_regions, :access_key, :principal_id, :use_managed_identities
   end
 end

test/client/test_client.rb

@@ -66,6 +66,18 @@ def test_without_credentials
     )
   end
 
+  def test_lazy_loading_doesnt_raise_before_querying
+    client = AzureBlob::Client.new(
+      account_name: @account_name,
+      container: @container,
+      lazy: true,
+    )
+
+    assert_raises(AzureBlob::Error) do
+      client.create_block_blob(key, content)
+    end
+  end
+
   def test_single_block_upload
     client.create_block_blob(key, content)