Add feature: exercism-cli.

Author: CodeMan99

src/exercism-cli/devcontainer-feature.json

@@ -0,0 +1,41 @@
+{
+    "name": "Exercism CLI",
+    "id": "exercism-cli",
+    "version": "1.0.0",
+    "description": "Install the exercism-cli.",
+    "options": {
+        "version": {
+            "default": "latest",
+            "description": "Specify what version to install.",
+            "type": "string"
+        },
+        "destdir": {
+            "default": "/usr/local/bin/",
+            "description": "Filesystem location of the exercism binary.",
+            "type": "string"
+        },
+        "os": {
+            "default": "linux",
+            "description": "Specify the target operating system.",
+            "enum": [
+                "darwin",
+                "freebsd",
+                "linux",
+                "openbsd"
+            ],
+            "type": "string"
+        },
+        "arch": {
+            "default": "x86_64",
+            "description": "Specify the target CPU architecture.",
+            "enum": [
+                "armv5",
+                "armv6",
+                "i386",
+                "ppc64",
+                "x86_64"
+            ],
+            "type": "string"
+        }
+    }
+}

src/exercism-cli/install.sh

@@ -0,0 +1,35 @@
+#!/usr/bin/env bash
+#
+# Install the Exercism CLI tool
+# https://github.com/exercism/cli
+#
+# Dependencies: curl, cut
+#
+# Environment:
+#   - VERSION: The version to install [default: latest].
+#   - DESTDIR: The destination of the executable [default: /usr/local/bin/].
+#   - OS: [default: linux]
+#   - ARCH: [default: x86_64]
+
+set -e
+
+GITHUB_BASE_URL="https://github.com/exercism/cli"
+LATEST_URL="${GITHUB_BASE_URL}/releases/latest/"
+DESTDIR="${DESTDIR:-/usr/local/bin}"
+OS="${OS:-linux}"
+ARCH="${ARCH:-x86_64}"
+
+if [[ -z "$VERSION" ]] || [[ "$VERSION" = "latest" ]]; then {
+    VERSION=$(curl -sLI -o /dev/null -w '%{url_effective}' "$LATEST_URL" | cut -d "v" -f 2)
+} fi
+
+echo "Installing exercism-cli: v${VERSION}"
+
+RELEASE_URL="${GITHUB_BASE_URL}/releases/download/v${VERSION}/exercism-${VERSION}-${OS}-${ARCH}.tar.gz"
+DOWNLOAD_DIR=$(mktemp -d || mktemp -d -t 'tmp')
+pushd "$DOWNLOAD_DIR"
+curl -sL --retry 3 "$RELEASE_URL" | tar -xz
+echo "Installing to $DESTDIR"
+install exercism "$DESTDIR"
+popd
+rm -r "$DOWNLOAD_DIR"

test/exercism-cli/test.sh

@@ -0,0 +1,9 @@
+#!/bin/bash
+
+set -e
+
+source dev-container-features-test-lib
+
+check "version" bash -c "exercism"
+
+reportResults