Terraform: Add proxy setting (#435) (#451)

* Terraform: Add proxy setting (#435)

* Terraform: Remove unused variable GPG_OPTS (#435)

* Terraform: Increment minor version (#435)

* Update src/terraform/install.sh
Co-authored-by: Samruddhi Khandale <skhandale@microsoft.com>

* Add feature option

* Update src/terraform/devcontainer-feature.json
Co-authored-by: Samruddhi Khandale <skhandale@microsoft.com>

* Update src/terraform/devcontainer-feature.json
Co-authored-by: Samruddhi Khandale <skhandale@microsoft.com>

* Update src/terraform/devcontainer-feature.json
Co-authored-by: Samruddhi Khandale <skhandale@microsoft.com>

* Terraform: Change environment variables to upper case (#435)

* Terraform: Use HTTP_PROXY as the default for connecting to keyservers (#435)

* Update src/terraform/install.sh
Co-authored-by: Samruddhi Khandale <samruddhikhandale@github.com>

---------
Co-authored-by: Samruddhi Khandale <skhandale@microsoft.com>
Co-authored-by: Samruddhi Khandale <samruddhikhandale@github.com>

src/terraform/devcontainer-feature.json

 {
     "id": "terraform",
-    "version": "1.2.0",
+    "version": "1.3.0",
     "name": "Terraform, tflint, and TFGrunt",
     "documentationURL": "https://github.com/devcontainers/features/tree/main/src/terraform",
     "description": "Installs the Terraform CLI and optionally TFLint and Terragrunt. Auto-detects latest version and installs needed dependencies.",
@@ -47,6 +47,11 @@
             "type": "boolean",
             "default": false,
             "description": "Install terraform-docs, a utility to generate documentation from Terraform modules"
+        },
+        "httpProxy": {
+            "type": "string",
+            "default": "",
+            "description": "Connect to a keyserver using a proxy by configuring this option"
         }
     },
     "customizations": {

src/terraform/install.sh

@@ -28,9 +28,10 @@ TERRAFORM_DOCS_SHA256="${TERRAFORM_DOCS_SHA256:-"automatic"}"
 
 TERRAFORM_GPG_KEY="72D7468F"
 TFLINT_GPG_KEY_URI="https://raw.githubusercontent.com/terraform-linters/tflint/master/8CE69160EB3F2FE9.key"
-GPG_KEY_SERVERS="keyserver hkp://keyserver.ubuntu.com
+GPG_KEY_SERVERS="keyserver hkps://keyserver.ubuntu.com
 keyserver hkps://keys.openpgp.org
-keyserver hkp://keyserver.pgp.com"
+keyserver hkps://keyserver.pgp.com"
+KEYSERVER_PROXY="${HTTPPROXY:-"${HTTP_PROXY:-""}"}"
 
 architecture="$(uname -m)"
 case ${architecture} in
@@ -53,6 +54,9 @@ receive_gpg_keys() {
     if [ ! -z "$2" ]; then
         keyring_args="--no-default-keyring --keyring $2"
     fi
+    if [ ! -z "${KEYSERVER_PROXY}" ]; then
+	keyring_args="${keyring_args} --keyserver-options http-proxy=${KEYSERVER_PROXY}"
+    fi
 
     # Use a temporary location for gpg keys to avoid polluting image
     export GNUPGHOME="/tmp/tmp-gnupg"