gha/e2e: Also test against moby master

.github/workflows/e2e.yml

@@ -37,6 +37,7 @@ jobs:
           - alpine
           - debian
         engine-version:
+          - master  # moby/moby-bin:master
           - rc  # latest rc
           - 29  # latest
           - 28  # latest - 1

e2e/compose-env.yaml

@@ -31,6 +31,7 @@ services:
         dockerfile: engine/Dockerfile
         args:
           ENGINE_VERSION: ${ENGINE_VERSION:-29}
+          ENGINE_SOURCE: ${ENGINE_SOURCE:-dind}
       privileged: true
       command: ['--insecure-registry=registry:5000', '--insecure-registry=privateregistry:5001', '--experimental']
       environment:

e2e/testdata/Dockerfile.connhelper-ssh

@@ -3,8 +3,16 @@
 # ENGINE_VERSION is the version of the (docker-in-docker) Docker Engine to
 # test against.
 ARG ENGINE_VERSION=29
+# ENGINE_SOURCE is "dind" or "moby-bin" (moby/moby-bin:master).
+ARG ENGINE_SOURCE=dind
 
-FROM docker:${ENGINE_VERSION}-dind
+FROM docker:${ENGINE_VERSION}-dind AS engine-dind
+
+# moby/moby-bin only has the daemon binaries.
+FROM docker:dind AS engine-moby-bin
+COPY --link --from=moby/moby-bin:master / /usr/local/bin/
+
+FROM engine-${ENGINE_SOURCE}
 
 # the openssh-client update is needed for security reasons when using docker:23.0-dind, currently maintained as an lts by mirantis
 RUN apk --no-cache add openssl openssh-client openssh-server shadow && \

e2e/testdata/engine/Dockerfile

@@ -1,5 +1,14 @@
 ARG ENGINE_VERSION
-FROM docker:${ENGINE_VERSION}-dind
+# ENGINE_SOURCE is "dind" or "moby-bin" (moby/moby-bin:master).
+ARG ENGINE_SOURCE=dind
+
+FROM docker:${ENGINE_VERSION}-dind AS engine-dind
+
+# moby/moby-bin only has the daemon binaries.
+FROM docker:dind AS engine-moby-bin
+COPY --link --from=moby/moby-bin:master / /usr/local/bin/
+
+FROM engine-${ENGINE_SOURCE}
 
 # Trust the tlsregistry CA so dockerd connects without --insecure-registry.
 COPY registry/certs/ca.crt /usr/local/share/ca-certificates/tlsregistry-ca.crt

scripts/test/e2e/run

@@ -42,6 +42,11 @@ setup() {
         sh e2e/testdata/registry/certs/gen-certs.sh
     fi
 
+    # ENGINE_VERSION=master tests against moby/moby-bin:master.
+    if [ "${ENGINE_VERSION:-}" = "master" ]; then
+        export ENGINE_SOURCE=moby-bin
+    fi
+
     COMPOSE_PROJECT_NAME=$project COMPOSE_FILE=$file docker compose up --build -d >&2
 
     # Ensure supporting services exist before running tests. If one fails to start,