test(docker): cover docker-ce-cli install and dind DOCKER_HOST fix

Dockerfile

@@ -11,13 +11,20 @@ RUN apt-get update && apt-get install -y --no-install-recommends \
     g++ \
     chromium \
     gnupg \
-    docker.io \
     ffmpeg \
     ripgrep \
     && rm -rf /var/lib/apt/lists/*
 
 RUN curl -LsSf https://astral.sh/uv/install.sh | UV_INSTALL_DIR=/usr/local/bin sh
 
+RUN mkdir -p -m 0755 /etc/apt/keyrings \
+    && curl -fsSL https://download.docker.com/linux/debian/gpg -o /etc/apt/keyrings/docker.asc \
+    && chmod a+r /etc/apt/keyrings/docker.asc \
+    && echo "deb [arch=$(dpkg --print-architecture) signed-by=/etc/apt/keyrings/docker.asc] https://download.docker.com/linux/debian trixie stable" | tee /etc/apt/sources.list.d/docker.list > /dev/null \
+    && apt-get update \
+    && apt-get install -y --no-install-recommends docker-ce-cli docker-compose-plugin \
+    && rm -rf /var/lib/apt/lists/*
+
 RUN mkdir -p -m 0755 /etc/apt/keyrings \
     && curl -fsSL https://cli.github.com/packages/githubcli-archive-keyring.gpg | gpg --dearmor -o /etc/apt/keyrings/githubcli-archive-keyring.gpg \
     && chmod go+r /etc/apt/keyrings/githubcli-archive-keyring.gpg \

docker-compose.yml

@@ -29,7 +29,7 @@ services:
     env_file:
       - .env
     environment:
-      - DOCKER_HOST=tcp://docker-dind:2375
+      - DOCKER_HOST=tcp://dind:2375
       - OPENCODE_CONFIG_DIR=/root/.config/opencode
       - OPENCODE_MEMORY_DIR=/root/.local/share/opencode/opencode-memory
       - DOCKER_CONTAINER=true

tests/test_docker_compose.py

@@ -242,6 +242,39 @@ def test_dind_limits_unchanged():
     assert "pids: 512" in dind_block
 
 
+# ── DOCKER_HOST points to a resolvable name (issue #222 — fix unresolvable host)
+
+
+def test_docker_host_uses_resolvable_name():
+    """opencode ``DOCKER_HOST`` points to the dind service alias ``dind``.
+
+    The compose service is named ``dind`` (``container_name:
+    opencode-docker-dind``). DNS inside the ``opencode_network`` resolves the
+    service name, so ``tcp://dind:2375`` works; the old ``tcp://docker-dind``
+    referenced no existing name and never resolved.
+    """
+    content = _compose_text()
+    assert "DOCKER_HOST=tcp://dind:2375" in content, (
+        "docker-compose.yml opencode DOCKER_HOST must point to `tcp://dind:2375` "
+        "(compose service alias) — the old `docker-dind` name does not resolve "
+        "in opencode_network (issue #222)"
+    )
+
+
+def test_docker_host_old_name_removed():
+    """Raw text check: ``docker-dind`` hostname is absent from DOCKER_HOST.
+
+    The old ``tcp://docker-dind:2375`` referenced neither the compose service
+    name (``dind``) nor the container name (``opencode-docker-dind``) and
+    never resolved inside ``opencode_network``.
+    """
+    content = _compose_text()
+    assert "DOCKER_HOST=tcp://docker-dind:2375" not in content, (
+        "docker-compose.yml must not retain the unresolvable `docker-dind` "
+        "hostname in DOCKER_HOST (issue #222)"
+    )
+
+
 if __name__ == "__main__":
     import pytest
 

tests/test_dockerfile.py

@@ -112,6 +112,69 @@ def test_single_npm_install_line_has_kept_packages():
         )
 
 
+# ── docker CLI install (issue #222 — docker-ce-cli + compose plugin) ─────────
+
+
+def test_docker_io_removed_from_apt_install():
+    """Dockerfile does NOT install the ``docker.io`` Debian metapackage.
+
+    The ``docker.io`` package on trixie ships ``dockerd`` + ``docker-proxy`` +
+    ``docker-init`` but NOT the ``docker`` CLI binary. The opencode container
+    delegates to the external DinD service, so running a local daemon is dead
+    weight — only the CLI is needed. ``docker-ce-cli`` (official Docker APT
+    repo) provides ``/usr/bin/docker`` and matches DinD 29.6.2 (API 1.55).
+    """
+    content = _dockerfile_text()
+    assert "docker.io" not in content, (
+        "Dockerfile must NOT install `docker.io` — trixie ships no `docker` "
+        "CLI binary, only the daemon; install `docker-ce-cli` instead (issue #222)"
+    )
+
+
+def test_docker_ce_cli_installed():
+    """Dockerfile installs ``docker-ce-cli`` from the official Docker APT repo.
+
+    Provides ``/usr/bin/docker`` and matches DinD 29.6.2 (API 1.55). The
+    Debian ``docker.io`` package does NOT ship the CLI on trixie.
+    """
+    content = _dockerfile_text()
+    assert "docker-ce-cli" in content, (
+        "Dockerfile must install `docker-ce-cli` so `which docker` resolves to "
+        "/usr/bin/docker and `docker version` reaches the DinD server (issue #222)"
+    )
+
+
+def test_docker_compose_plugin_installed():
+    """Dockerfile installs ``docker-compose-plugin`` (Compose v2 subcommand).
+
+    The old Python ``docker-compose`` (v1) is NOT compatible. ``docker
+    compose`` (subcommand) requires the plugin, bundled with the official
+    Docker APT repo alongside ``docker-ce-cli``.
+    """
+    content = _dockerfile_text()
+    assert "docker-compose-plugin" in content, (
+        "Dockerfile must install `docker-compose-plugin` so `docker compose "
+        "version` prints v2.x (issue #222)"
+    )
+
+
+def test_docker_apt_repo_added():
+    """Dockerfile adds the official Docker APT repository (``download.docker.com``).
+
+    ``docker-ce-cli`` / ``docker-compose-plugin`` are not in the Debian
+    trixie default repos — the official Docker repo is required to match the
+    DinD version (29.6.2, API 1.55).
+    """
+    content = _dockerfile_text()
+    assert "download.docker.com/linux/debian" in content, (
+        "Dockerfile must add the official Docker APT repo (download.docker.com) "
+        "to install docker-ce-cli matching DinD 29.6.2 (issue #222)"
+    )
+    assert "triex" not in content.replace("trixie", ""), (
+        "Dockerfile Docker APT repo must target the trixie suite (matches base image)"
+    )
+
+
 if __name__ == "__main__":
     import pytest