Dev Containers: Add initializeCommand

- Support SSH agent forwarding
- Update LICENSE
- Update .devcontainer/.gitignore

Author: benz0li

.devcontainer/.gitignore

@@ -27,6 +27,8 @@
 
 !/devcontainer.json
 !/GHC.Dockerfile
+!/init
+!/init.cmd
 !/LICENSE
 !/README.md
 

.devcontainer/LICENSE

@@ -33,3 +33,10 @@ https://github.com/devcontainers/features/blob/main/LICENSE for
 license information.
 
 --------------------------------------------------------------------------------
+.devcontainer/init
+Copyright (c) 2025 b-data GmbH
+Copyright (c) 2023 Microsoft Corporation
+
+Distributed under the terms of the MIT License.
+
+--------------------------------------------------------------------------------

.devcontainer/devcontainer.json

@@ -12,6 +12,7 @@
     }
   },
 
+  "initializeCommand": [".devcontainer/init"],
   "onCreateCommand": "onCreateCommand.sh",
   "postCreateCommand": "postCreateCommand.sh",
 

.devcontainer/ghc-9.10.2/devcontainer.json

@@ -12,6 +12,7 @@
     }
   },
 
+  "initializeCommand": [".devcontainer/init"],
   "onCreateCommand": "onCreateCommand.sh",
   "postCreateCommand": "postCreateCommand.sh",
 

.devcontainer/ghc-9.12.2/devcontainer.json

@@ -12,6 +12,7 @@
     }
   },
 
+  "initializeCommand": [".devcontainer/init"],
   "onCreateCommand": "onCreateCommand.sh",
   "postCreateCommand": "postCreateCommand.sh",
 

.devcontainer/init

@@ -0,0 +1,32 @@
+#!/usr/bin/env bash
+# Copyright (c) 2025 b-data GmbH
+# Copyright (c) 2023 Microsoft Corporation
+# Distributed under the terms of the MIT License.
+#
+# https://code.visualstudio.com/remote/advancedcontainers/sharing-git-credentials
+# https://docs.github.com/en/authentication/connecting-to-github-with-ssh/working-with-ssh-key-passphrases?platform=windows
+#
+# Modified by b-data for seamless use with development containers.
+
+set -e
+
+if [ -z "$CODESPACES" ] && [ "$(command -v ssh-agent)" ]; then
+  if [ -z "$SSH_AUTH_SOCK" ]; then
+    # Check for a currently running instance of the agent
+    RUNNING_AGENT="$(pgrep -f 'ssh-agent -s' | wc -l | tr -d '[:space:]')"
+    if [ "$RUNNING_AGENT" = "0" ] || [ ! -f "$HOME/.ssh/ssh-agent" ]; then
+      mkdir -p -m 0700 "$HOME/.ssh"
+      # Launch a new instance of the agent
+      ssh-agent -s &> "$HOME/.ssh/ssh-agent"
+    fi
+    eval "$(cat "$HOME/.ssh/ssh-agent")" > /dev/null
+  fi
+  # Check the state of the currently running instance of the agent
+  # 0: running with key(s); 1: running w/o key(s); 2: not running
+  AGENT_RUN_STATE="$(ssh-add -l > /dev/null 2>&1; echo $?)"
+  # Only add key(s) if running w/o key(s)
+  if [ "$AGENT_RUN_STATE" = "1" ]; then
+    ssh-add 2> /dev/null || true
+  fi
+  # Means: Not adding key(s) to a forwarded agent with key(s)
+fi