[Bug]: panic when connecting to colima 0.9.1

[jmhodges]

Testcontainers version

0.39.0

Using the latest Testcontainers version?

Yes

Host OS

macOS 26.0.1

Host arch

ARM

Go version

1.25.3

Docker version

$  docker version
Client:
 Version:           28.5.1
 API version:       1.51
 Go version:        go1.24.8
 Git commit:        e180ab8
 Built:             Wed Oct  8 12:16:17 2025
 OS/Arch:           darwin/arm64
 Context:           colima

Server: Docker Engine - Community
 Engine:
  Version:          28.4.0
  API version:      1.51 (minimum version 1.24)
  Go version:       go1.24.7
  Git commit:       249d679
  Built:            Wed Sep  3 20:58:55 2025
  OS/Arch:          linux/arm64
  Experimental:     false
 containerd:
  Version:          1.7.27
  GitCommit:        05044ec0a9a75232cad458027ca83437aae3f4da
 runc:
  Version:          1.2.5
  GitCommit:        v1.2.5-0-g59923ef
 docker-init:
  Version:          0.19.0
  GitCommit:        de40ad0

Docker info

$  docker info
Client:
 Version:    28.5.1
 Context:    colima
 Debug Mode: false
 Plugins:
  ai: Docker AI Agent - Ask Gordon (Docker Inc.)
    Version:  v1.9.11
    Path:     /Users/jmhodges/.docker/cli-plugins/docker-ai
  buildx: Docker Buildx (Docker Inc.)
    Version:  v0.29.1
    Path:     /opt/homebrew/lib/docker/cli-plugins/docker-buildx
  compose: Docker Compose (Docker Inc.)
    Version:  2.40.2
    Path:     /opt/homebrew/lib/docker/cli-plugins/docker-compose
  debug: Get a shell into any image or container (Docker Inc.)
    Version:  0.0.45
    Path:     /Users/jmhodges/.docker/cli-plugins/docker-debug
  desktop: Docker Desktop commands (Docker Inc.)
    Version:  v0.2.0
    Path:     /Users/jmhodges/.docker/cli-plugins/docker-desktop
  extension: Manages Docker extensions (Docker Inc.)
    Version:  v0.2.31
    Path:     /Users/jmhodges/.docker/cli-plugins/docker-extension
  init: Creates Docker-related starter files for your project (Docker Inc.)
    Version:  v1.4.0
    Path:     /Users/jmhodges/.docker/cli-plugins/docker-init
  mcp: Docker MCP Plugin (Docker Inc.)
    Version:  v0.24.0
    Path:     /Users/jmhodges/.docker/cli-plugins/docker-mcp
  model: Docker Model Runner (Docker Inc.)
    Version:  v0.1.46
    Path:     /Users/jmhodges/.docker/cli-plugins/docker-model
  offload: Docker Offload (Docker Inc.)
    Version:  v0.5.1
    Path:     /Users/jmhodges/.docker/cli-plugins/docker-offload
  sandbox: Docker Sandbox (Docker Inc.)
    Version:  v0.3.1
    Path:     /Users/jmhodges/.docker/cli-plugins/docker-sandbox
  sbom: View the packaged-based Software Bill Of Materials (SBOM) for an image (Anchore Inc.)
    Version:  0.6.0
    Path:     /Users/jmhodges/.docker/cli-plugins/docker-sbom
  scout: Docker Scout (Docker Inc.)
    Version:  v1.18.3
    Path:     /Users/jmhodges/.docker/cli-plugins/docker-scout

Server:
 Containers: 5
  Running: 0
  Paused: 0
  Stopped: 5
 Images: 3
 Server Version: 28.4.0
 Storage Driver: overlayfs
  driver-type: io.containerd.snapshotter.v1
 Logging Driver: json-file
 Cgroup Driver: cgroupfs
 Cgroup Version: 2
 Plugins:
  Volume: local
  Network: bridge host ipvlan macvlan null overlay
  Log: awslogs fluentd gcplogs gelf journald json-file local splunk syslog
 CDI spec directories:
  /etc/cdi
  /var/run/cdi
 Swarm: inactive
 Runtimes: io.containerd.runc.v2 runc
 Default Runtime: runc
 Init Binary: docker-init
 containerd version: 05044ec0a9a75232cad458027ca83437aae3f4da
 runc version: v1.2.5-0-g59923ef
 init version: de40ad0
 Security Options:
  apparmor
  seccomp
   Profile: builtin
  cgroupns
 Kernel Version: 6.8.0-64-generic
 Operating System: Ubuntu 24.04.2 LTS
 OSType: linux
 Architecture: aarch64
 CPUs: 2
 Total Memory: 1.913GiB
 Name: colima
 ID: e88d1fcd-d1e2-4c00-bd57-eb42fab7ac7e
 Docker Root Dir: /var/lib/docker
 Debug Mode: false
 Experimental: false
 Insecure Registries:
  ::1/128
  127.0.0.0/8
 Live Restore Enabled: false

What happened?

When trying to create a postgres (or mariadb) database container with a colima 0.9.1 docker server on macOS 26.0.1, a panic happens deep in MustExtractDockerHost.

I followed the instructions for Colima (specifically the ones for versions of colima newer than 0.9.1).

That is, I ran docker context use colima and saw it correctly running.

Output of `docker context ls`

$  docker context ls 
NAME            DESCRIPTION                               DOCKER ENDPOINT                                      ERROR
colima *        colima                                    unix:///Users/jmhodges/.colima/default/docker.sock   
default         Current DOCKER_HOST based configuration   unix:///var/run/docker.sock                          
desktop-linux   Docker Desktop                            unix:///Users/jmhodges/.docker/run/docker.sock       

I then ran some example code. I've simplified it to this test:

func TestFoo(t *testing.T) {
	s, err := run()
	if err != nil {
		t.Fatalf("Error: %s\n", err)
	}
	t.Logf("Connection string: %s\n", s)
}

func run() (string, error) {
	ctx := context.Background()
	container, err := postgres.Run(ctx,
		"postgres:16-alpine",
		postgres.WithDatabase("test"),
		postgres.WithUsername("user"),
		postgres.WithPassword("password"),
	)
	if err != nil {
		return "", fmt.Errorf("failed to start Postgres container: %w", err)
	}
	connStr, err := container.ConnectionString(ctx)
	if err != nil {
		container.Terminate(ctx)
		return "", fmt.Errorf("failed to get connection string: %w", err)
	}
	return connStr, nil
}

$  go test -v -run Foo
=== RUN   TestFoo
--- FAIL: TestFoo (0.00s)
panic: rootless Docker not found [recovered, repanicked]

goroutine 8 [running]:
testing.tRunner.func1.2({0x102e315c0, 0x140000107e0})
	/opt/homebrew/Cellar/go/1.25.3/libexec/src/testing/testing.go:1872 +0x190
testing.tRunner.func1()
	/opt/homebrew/Cellar/go/1.25.3/libexec/src/testing/testing.go:1875 +0x31c
panic({0x102e315c0?, 0x140000107e0?})
	/opt/homebrew/Cellar/go/1.25.3/libexec/src/runtime/panic.go:783 +0x120
github.com/testcontainers/testcontainers-go/internal/core.MustExtractDockerHost.func1()
	/Users/jmhodges/src/local/vendor/github.com/testcontainers/testcontainers-go/internal/core/docker_host.go:91 +0x68
sync.(*Once).doSlow(0x14000030000?, 0x0?)
	/opt/homebrew/Cellar/go/1.25.3/libexec/src/sync/once.go:78 +0xe0
sync.(*Once).Do(...)
	/opt/homebrew/Cellar/go/1.25.3/libexec/src/sync/once.go:69
github.com/testcontainers/testcontainers-go/internal/core.MustExtractDockerHost({0x102ee2308?, 0x10322d280?})
	/Users/jmhodges/src/local/vendor/github.com/testcontainers/testcontainers-go/internal/core/docker_host.go:88 +0x54
github.com/testcontainers/testcontainers-go/internal/core.NewClient({0x102ee2308, 0x10322d280}, {0x0, 0x0, 0x0?})
	/Users/jmhodges/src/local/vendor/github.com/testcontainers/testcontainers-go/internal/core/client.go:17 +0x88
github.com/testcontainers/testcontainers-go.NewDockerClientWithOpts({0x102ee2308, 0x10322d280}, {0x0, 0x0, 0x0})
	/Users/jmhodges/src/local/vendor/github.com/testcontainers/testcontainers-go/docker_client.go:118 +0x4c
github.com/testcontainers/testcontainers-go.NewDockerProvider({0x14000262480, 0x2, 0x102cfe50e?})
	/Users/jmhodges/src/local/vendor/github.com/testcontainers/testcontainers-go/provider.go:144 +0xfc
github.com/testcontainers/testcontainers-go.ProviderType.GetProvider(0x0, {0x140000ccfc8, 0x1, 0x0?})
	/Users/jmhodges/src/local/vendor/github.com/testcontainers/testcontainers-go/provider.go:115 +0x784
github.com/testcontainers/testcontainers-go.GenericContainer({_, _}, {{{{0x0, 0x0}, {0x0, 0x0}, {0x0, 0x0}, {0x0, 0x0}, ...}, ...}, ...})
	/Users/jmhodges/src/local/vendor/github.com/testcontainers/testcontainers-go/generic.go:62 +0xe8
github.com/testcontainers/testcontainers-go/modules/postgres.Run({0x102ee2308, 0x10322d280}, {0x102d0196b?, 0x12?}, {0x140000cdec0, 0x3, 0x3?})
	/Users/jmhodges/src/local/vendor/github.com/testcontainers/testcontainers-go/modules/postgres/postgres.go:186 +0x328
local.run()
	/Users/jmhodges/src/local/foo_test.go:42 +0x118
local.TestFoo(0x140000fe700)
	/Users/jmhodges/src/local/foo_test.go:33 +0x20
testing.tRunner(0x140000fe700, 0x102ed88f0)
	/opt/homebrew/Cellar/go/1.25.3/libexec/src/testing/testing.go:1934 +0xc8
created by testing.(*T).Run in goroutine 1
	/opt/homebrew/Cellar/go/1.25.3/libexec/src/testing/testing.go:1997 +0x364
exit status 2
FAIL	local	0.414s

Setting the DOCKER_HOST explicitly gets you further, but not far enough.

$  env DOCKER_HOST=unix:///Users/jmhodges/.colima/default/docker.sock go test -v -run Foo   
=== RUN   TestFoo
2025/10/31 03:44:31 github.com/testcontainers/testcontainers-go - Connected to docker: 
  Server Version: 28.4.0
  API Version: 1.51
  Operating System: Ubuntu 24.04.2 LTS
  Total Memory: 1959 MB
  Testcontainers for Go Version: v0.39.0
  Resolved Docker Host: unix:///Users/jmhodges/.colima/default/docker.sock
  Resolved Docker Socket Path: /Users/jmhodges/.colima/default/docker.sock
  Test SessionID: de6633547b5d706409a4866f17e360744751c288e1abe81b22581a16e2b4b9a3
  Test ProcessID: e4ecc230-fc56-468d-abbd-27e72856b143
2025/10/31 03:44:31 🐳 Creating container for image postgres:16-alpine
2025/10/31 03:44:31 🐳 Creating container for image testcontainers/ryuk:0.13.0
2025/10/31 03:44:31 ✅ Container created: cddafa0468e5
2025/10/31 03:44:31 🐳 Starting container: cddafa0468e5
2025/10/31 03:44:31 🐳 Stopping container: cddafa0468e5
2025/10/31 03:44:31 🐳 Terminating container: cddafa0468e5
2025/10/31 03:44:31 🚫 Container terminated: cddafa0468e5
    foo_test.go:35: Error: failed to start Postgres container: generic container: create container: reaper: new reaper: run container: container start: Error response from daemon: error while creating mount source path '/Users/jmhodges/.colima/default/docker.sock': mkdir /Users/jmhodges/.colima/default/docker.sock: operation not supported: could not start container
--- FAIL: TestFoo (0.13s)
FAIL
exit status 1
FAIL	local	0.404s

Any idea what the correct way to talk to colima is? And possibly why it's different from other docker installations? Or is there something interesting about my colima server?

Relevant log output

Additional information

You'll notice I have a docker desktop install, but I shut it down before this.

[jmhodges]

(I also tried with colima start --network-address and hit the same errors.)

[jessicasomaiya]

I had the same problem, looks like it's been an ongoing issue with colima. Looking at other threads, settingDOCKER_HOST and TESTCONTAINERS_DOCKER_SOCKET_OVERRIDE should do the trick as a workaround.

export TESTCONTAINERS_DOCKER_SOCKET_OVERRIDE=/var/run/docker.sock
export DOCKER_HOST="unix://${HOME}/.colima/docker.sock"