address comments

src/docker-in-docker/devcontainer-feature.json

@@ -1,6 +1,6 @@
 {
     "id": "docker-in-docker",
-    "version": "2.2.2",
+    "version": "2.3.0",
     "name": "Docker (Docker-in-Docker)",
     "documentationURL": "https://github.com/devcontainers/features/tree/main/src/docker-in-docker",
     "description": "Create child containers *inside* a container, independent from the host's docker instance. Installs Docker extension in the container along with needed CLIs.",

src/docker-in-docker/install.sh

@@ -347,7 +347,7 @@ fi
 
 tee /usr/local/share/docker-init.sh > /dev/null \
 << EOF
-#!/usr/bin/env bash
+#!/bin/sh
 #-------------------------------------------------------------------------------------------------------------
 # Copyright (c) Microsoft Corporation. All rights reserved.
 # Licensed under the MIT License. See https://go.microsoft.com/fwlink/?linkid=2090316 for license information.
@@ -440,7 +440,7 @@ do
 
         if [ "${docker_ok}" != "true" ]; then
             echo "(*) Failed to start docker, retrying in 5s..."
-            (( retry_count++ ))
+            retry_count=`expr $retry_count + 1`
             sleep 5s
         fi
     set -e

test/docker-in-docker/docker_retry.sh

@@ -0,0 +1,32 @@
+#!/bin/bash
+
+set -e
+
+# Optional: Import test library
+source dev-container-features-test-lib
+
+# Definition specific tests
+check "docker-buildx" docker buildx version
+check "docker-ps" docker ps
+
+sleep 5s
+
+# Stop docker
+pkill dockerd
+pkill containerd
+
+sleep 5s
+
+set +e
+    docker_ok_code="$(docker info > /dev/null 2>&1; echo $?)"
+set -e
+
+check "docker-not-running" bash -c "[[ ${docker_ok_code} == 1 ]]"
+
+#  Testing retry logic
+./test-scripts/docker-test-init.sh
+
+check "docker-started-after-retries" docker ps
+
+# Report result
+reportResults

test/docker-in-docker/scenarios.json

@@ -67,6 +67,11 @@
             }
         },
         "remoteUser": "node"
+    },
+    "docker_retry": {
+        "image": "ubuntu:focal",
+        "features": {
+            "docker-in-docker": {}
+        }
     }
-
 }

test/docker-in-docker/test-scripts/docker-test-init.sh

@@ -0,0 +1,26 @@
+#!/bin/sh
+#-------------------------------------------------------------------------------------------------------------
+# Copyright (c) Microsoft Corporation. All rights reserved.
+# Licensed under the MIT License. See https://go.microsoft.com/fwlink/?linkid=2090316 for license information.
+#-------------------------------------------------------------------------------------------------------------
+
+retry_count=0
+docker_ok="false"
+
+until [ "${docker_ok}" = "true"  ] || [ "${retry_count}" -eq "5" ];
+do
+    if [ "${retry_count}" -eq "3" ]; then
+        echo "Starting docker after 3 retries..."
+        /usr/local/share/docker-init.sh
+    fi
+
+    set +e
+        docker info > /dev/null 2>&1 && docker_ok="true"
+
+        if [ "${docker_ok}" != "true" ]; then
+            echo "(*) Failed to start docker, retrying in 5s... Retry count: ${retry_count}"
+            retry_count=`expr $retry_count + 1`
+            sleep 1s
+        fi
+    set -e
+done