Don't require both --mount for using --mount-string and remove default mount-string #21250

nirs · 2025-08-05T22:16:41Z

The --mount-string argument defaults to /Users on darwin, and homedir.Homedir() on other platforms (e.g. $HOME on unix).

This is wrong in many ways:

/Users is not $HOME on darwin (the right path is /Users/$USER). Using the default mount we cannot access anything inside the guest in the user home directory. We can access the special /Users/Shared directory, but this should not be a default mount.
Mounting the user home directory inside the guest in read-write mode is a horrible default. This exposes the users private keys in .ssh/ to the guest, any sensitive files in the user home directory, and allows the guest to change any file on the host.
Using the --mount option mounts the default mount directory silently. This is unexpected, surprising, and not documented in the minikube handbook[1].

Example access to user private key from the guest with the default mount:

$ minikube start --mount

$ minikube ssh cat /minikube-host/.ssh/id_ed25519
-----BEGIN OPENSSH PRIVATE KEY-----
...
-----END OPENSSH PRIVATE KEY-----

Fixed by removing the default mount directory and changing mount logic to check for non-empty mount-string instead of the mount flag.

The mount flag is kept for backward compatibility, but its value is ignored. In the next release we want to use this flag for supporting multiple mounts.

Example usage before:

minikube start --mount --mount-string ~/models:/mnt/models

Example usage after:

minikube start --mount-string ~/models:/mnt/models

Breaking changes:

User depending the default mount will have to replace the command:

minikube start --mount

With:

minikube start  --mount-string $HOME:/minikube-host

[1] https://minikube.sigs.k8s.io/docs/handbook/mount/

nirs · 2025-08-05T22:33:11Z

/ok-to-test

pkg/minikube/constants/constants_darwin.go

medyagh · 2025-08-05T22:35:03Z

I agree, we should not mount the home folder to ppl's minikubes by default that was a horrible default of some drivers. I am okay with breaking change if we can get rid of it by default

nirs · 2025-08-09T00:16:16Z

Changes in latest version:

Fix TestMountStart to use --mount-string instead of --mount
Rebase on master

nirs · 2025-08-09T15:52:39Z

/retest

nirs · 2025-08-09T15:59:26Z

/cc @afbjorklund

nirs · 2025-08-09T16:16:23Z

/kind improvement

nirs · 2025-08-09T16:17:14Z

/kind api-change

nirs · 2025-08-09T16:33:26Z

/remove-kind api-change

medyagh · 2025-08-09T21:29:31Z

cmd/minikube/cmd/start_flags.go

@@ -173,8 +173,8 @@ func initMinikubeFlags() {
 	startCmd.Flags().Bool(keepContext, false, "This will keep the existing kubectl context and will create a minikube context.")
 	startCmd.Flags().Bool(embedCerts, false, "if true, will embed the certs in kubeconfig.")
 	startCmd.Flags().StringP(containerRuntime, "c", constants.DefaultContainerRuntime, fmt.Sprintf("The container runtime to be used. Valid options: %s (default: auto)", strings.Join(cruntime.ValidRuntimes(), ", ")))
-	startCmd.Flags().Bool(createMount, false, "This will start the mount daemon and automatically mount files into minikube.")
-	startCmd.Flags().String(mountString, constants.DefaultMountDir+":/minikube-host", "The argument to pass the minikube mount command on start.")
+	startCmd.Flags().Bool(createMount, false, "Kept for backward compatibility, value is ignored.")


we can consider hiding this flag (we have a few flags that hidden since we dont want ppl to use them, but left for backward campatiblitiy

Hiding the flag will hide the useful help message. I think we should keep if for now. If we don't use it in the next releases we can hide it.

medyagh

Question: does this mean we need to update this site page about "built-in host folder sharing"?
Driver mounts
Some hypervisors, have built-in host folder sharing. Driver mounts are reliable with good performance, but the paths are not predictable across operating systems or hypervis

https://minikube.sigs.k8s.io/docs/handbook/mount/

nirs · 2025-08-09T22:00:55Z

Question: does this mean we need to update this site page about "built-in host folder sharing"? Driver mounts Some hypervisors, have built-in host folder sharing. Driver mounts are reliable with good performance, but the paths are not predictable across operating systems or hypervis

https://minikube.sigs.k8s.io/docs/handbook/mount/

This change does not effect built in mounts - these are not done using 9p so they should not be affected by ignoring the --mount flag. These should be disable by --disable-driver-mounts which we did not touch.

So I don't think any update is needed, the only change is the detail of using --mount flag which is not documented in the handbook.

test/integration/mount_start_test.go

The --mount-string argument defaults to `/Users` on darwin, and homedir.Homedir() on other platforms (e.g. $HOME on unix). This is wrong in many ways: - `/Users` is not HOME on darwin (the right path is `/Users/$USER`). Using the default mount we cannot access anything inside the guest in the user home directory. We can access the special `/Users/Shared` directory, but this should not be a default mount. - Mounting the user home directory inside the guest in read-write mode is a horrible default. This exposes the users private keys in .ssh/ to the guest, any sensitive files in the user home directory, and allows the guest to change any file on the host. - Using the `--mount` option mount the default mount directory silently. This is unexpected, surprising, and not documented in the minikube handbook[1]. Example access to user private key from the guest with the default mount: $ minikube start --mount $ minikube ssh cat /minikube-host/.ssh/id_ed25519 -----BEGIN OPENSSH PRIVATE KEY----- ... -----END OPENSSH PRIVATE KEY----- Fixed by removing the default mount directory and changing mount logic to check for non-empty mount-string instead of the mount flag. The mount flag is kept for backward compatibility, but its value is ignored. In the next release we want to use this flag for supporting multiple mounts. Example usage before: minikube start --mount --mount-string ~/models:/mnt/models Example usage after: minikube start --mount-string ~/models:/mnt/models Breaking changes: User depending the default mount will have to replace the command: minikube start --mount With: minikube start --mount-string $HOME:/minikube-host [1] https://minikube.sigs.k8s.io/docs/handbook/mount/

nirs · 2025-08-10T01:32:50Z

Rebased to consume the docker service fix

medyagh · 2025-08-10T17:54:16Z

/retest-this-please

minikube-pr-bot · 2025-08-10T22:54:28Z

kvm2 driver with docker runtime

┌────────────────┬──────────┬────────────────────────┐
│    COMMAND     │ MINIKUBE │ MINIKUBE  ( PR 21250 ) │
├────────────────┼──────────┼────────────────────────┤
│ minikube start │ 47.7s    │ 48.9s                  │
│ enable ingress │ 14.8s    │ 15.0s                  │
└────────────────┴──────────┴────────────────────────┘

Times for minikube start: 47.8s 48.8s 46.8s 45.9s 49.3s
Times for minikube (PR 21250) start: 46.4s 49.6s 51.4s 48.0s 49.1s

Times for minikube ingress: 14.9s 14.9s 14.9s 14.4s 14.9s
Times for minikube (PR 21250) ingress: 14.9s 14.9s 14.9s 14.9s 15.5s

docker driver with docker runtime

┌────────────────┬──────────┬────────────────────────┐
│    COMMAND     │ MINIKUBE │ MINIKUBE  ( PR 21250 ) │
├────────────────┼──────────┼────────────────────────┤
│ minikube start │ 23.1s    │ 23.2s                  │
│ enable ingress │ 12.9s    │ 12.5s                  │
└────────────────┴──────────┴────────────────────────┘

Times for minikube start: 22.6s 23.4s 24.6s 23.5s 21.5s
Times for minikube (PR 21250) start: 25.4s 21.0s 22.7s 21.9s 24.9s

Times for minikube (PR 21250) ingress: 12.3s 13.2s 12.7s 11.2s 13.2s
Times for minikube ingress: 12.7s 13.7s 13.2s 12.2s 12.7s

docker driver with containerd runtime

┌────────────────┬──────────┬────────────────────────┐
│    COMMAND     │ MINIKUBE │ MINIKUBE  ( PR 21250 ) │
├────────────────┼──────────┼────────────────────────┤
│ minikube start │ 23.0s    │ 22.9s                  │
│ enable ingress │ 23.3s    │ 24.3s                  │
└────────────────┴──────────┴────────────────────────┘

Times for minikube start: 24.6s 23.4s 22.8s 22.5s 21.5s
Times for minikube (PR 21250) start: 21.6s 22.2s 23.3s 22.8s 24.4s

Times for minikube ingress: 23.2s 23.7s 23.7s 23.2s 22.7s
Times for minikube (PR 21250) ingress: 22.7s 23.2s 30.2s 22.7s 22.7s

nirs · 2025-08-11T18:21:30Z

/retest

medyagh · 2025-08-11T18:29:13Z

cmd/minikube/cmd/start_flags.go

@@ -173,8 +173,8 @@ func initMinikubeFlags() {
 	startCmd.Flags().Bool(keepContext, false, "This will keep the existing kubectl context and will create a minikube context.")
 	startCmd.Flags().Bool(embedCerts, false, "if true, will embed the certs in kubeconfig.")
 	startCmd.Flags().StringP(containerRuntime, "c", constants.DefaultContainerRuntime, fmt.Sprintf("The container runtime to be used. Valid options: %s (default: auto)", strings.Join(cruntime.ValidRuntimes(), ", ")))
-	startCmd.Flags().Bool(createMount, false, "This will start the mount daemon and automatically mount files into minikube.")
-	startCmd.Flags().String(mountString, constants.DefaultMountDir+":/minikube-host", "The argument to pass the minikube mount command on start.")
+	startCmd.Flags().Bool(createMount, false, "Kept for backward compatibility, value is ignored.")


help text, this will be depricated and merged with --mount-string in the next version

Opened #21291, I'll try to get this into 1.37.

medyagh · 2025-08-11T18:37:55Z

/lgtm

k8s-ci-robot · 2025-08-11T18:38:06Z

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The --mount-string argument defaults to `/Users` on darwin, and homedir.Homedir() on other platforms (e.g. $HOME on unix). This is wrong in many ways: - `/Users` is not HOME on darwin (the right path is `/Users/$USER`). Using the default mount we cannot access anything inside the guest in the user home directory. We can access the special `/Users/Shared` directory, but this should not be a default mount. - Mounting the user home directory inside the guest in read-write mode is a horrible default. This exposes the users private keys in .ssh/ to the guest, any sensitive files in the user home directory, and allows the guest to change any file on the host. - Using the `--mount` option mount the default mount directory silently. This is unexpected, surprising, and not documented in the minikube handbook[1]. Example access to user private key from the guest with the default mount: $ minikube start --mount $ minikube ssh cat /minikube-host/.ssh/id_ed25519 -----BEGIN OPENSSH PRIVATE KEY----- ... -----END OPENSSH PRIVATE KEY----- Fixed by removing the default mount directory and changing mount logic to check for non-empty mount-string instead of the mount flag. The mount flag is kept for backward compatibility, but its value is ignored. In the next release we want to use this flag for supporting multiple mounts. Example usage before: minikube start --mount --mount-string ~/models:/mnt/models Example usage after: minikube start --mount-string ~/models:/mnt/models Breaking changes: User depending the default mount will have to replace the command: minikube start --mount With: minikube start --mount-string $HOME:/minikube-host [1] https://minikube.sigs.k8s.io/docs/handbook/mount/

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drivers: Add support for Virtiofs mounts for vfkit and krunkit #21149

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nirs force-pushed the fix-default-mount branch from b437fb3 to 8191cbc Compare August 9, 2025 00:12

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test: Initial support for virtiofs mounts #21272

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WIP: Use a well known 9p port range instead of random port #21275

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medyagh changed the title ~~start: Simpler and safer mount on start~~ dont require both --mount for using --mount-string and remove default mounted folders Aug 11, 2025

medyagh changed the title ~~dont require both --mount for using --mount-string and remove default mounted folders~~ Don't require both --mount for using --mount-string and remove default mounted folders Aug 11, 2025

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medyagh merged commit a82e25a into kubernetes:master Aug 11, 2025
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nirs changed the title ~~Don't require both --mount for using --mount-string and remove default mounted folders~~ Don't require both --mount for using --mount-string and remove default mount-string Aug 12, 2025

nirs mentioned this pull request Aug 12, 2025

Warn about using the ignored --mount option #21291

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Don't require both --mount for using --mount-string and remove default mount-string #21250

Don't require both --mount for using --mount-string and remove default mount-string #21250

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