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add var.ssh_options to pass additional SSH options to nixos-rebuild #427

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d0ea698
add var.ssh_options to pass additional SSH options to nixos-rebuild
threddast Nov 19, 2024
a03c430
change ssh_options to a list of strings
threddast Dec 5, 2024
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51 changes: 26 additions & 25 deletions terraform/all-in-one.md
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1 change: 1 addition & 0 deletions terraform/all-in-one/main.tf
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Original file line number Diff line number Diff line change
Expand Up @@ -55,6 +55,7 @@ module "nixos-rebuild" {
target_host = var.target_host
target_user = var.target_user
target_port = var.target_port
ssh_options = var.ssh_options
}

output "result" {
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9 changes: 9 additions & 0 deletions terraform/all-in-one/variables.tf
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Expand Up @@ -51,6 +51,15 @@ variable "target_port" {
default = 22
}

variable "ssh_options" {
type = map(string)
description = "Additional options to pass to the SSH command used to connect to the target_host after installing NixOS."
default = {
UserKnownHostsFile = "/dev/null"
StrictHostKeyChecking = "no"
}
}

variable "instance_id" {
type = string
description = "The instance id of the target_host, used to track when to reinstall the machine"
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17 changes: 9 additions & 8 deletions terraform/nixos-rebuild.md
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Expand Up @@ -50,14 +50,15 @@ No modules.

## Inputs

| Name | Description | Type | Default | Required |
| -------------------------------------------------------------------------------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------ | -------- | -------- | :------: |
| <a name="input_ignore_systemd_errors"></a> [ignore\_systemd\_errors](#input_ignore_systemd_errors) | Ignore systemd errors happening during deploy | `bool` | `false` | no |
| <a name="input_nixos_system"></a> [nixos\_system](#input_nixos_system) | The nixos system to deploy | `string` | n/a | yes |
| <a name="input_ssh_private_key"></a> [ssh\_private\_key](#input_ssh_private_key) | Content of private key used to connect to the target\_host. If set to - no key is passed to openssh and ssh will use its own configuration | `string` | `"-"` | no |
| <a name="input_target_host"></a> [target\_host](#input_target_host) | DNS host to deploy to | `string` | n/a | yes |
| <a name="input_target_port"></a> [target\_port](#input_target_port) | SSH port used to connect to the target\_host | `number` | `22` | no |
| <a name="input_target_user"></a> [target\_user](#input_target_user) | User to deploy as | `string` | `"root"` | no |
| Name | Description | Type | Default | Required |
| -------------------------------------------------------------------------------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------ | ------------- | --------------------------------------------------------------------------------------- | :------: |
| <a name="input_ignore_systemd_errors"></a> [ignore\_systemd\_errors](#input_ignore_systemd_errors) | Ignore systemd errors happening during deploy | `bool` | `false` | no |
| <a name="input_nixos_system"></a> [nixos\_system](#input_nixos_system) | The nixos system to deploy | `string` | n/a | yes |
| <a name="input_ssh_private_key"></a> [ssh\_private\_key](#input_ssh_private_key) | Content of private key used to connect to the target\_host. If set to - no key is passed to openssh and ssh will use its own configuration | `string` | `"-"` | no |
| <a name="input_target_host"></a> [target\_host](#input_target_host) | DNS host to deploy to | `string` | n/a | yes |
| <a name="input_target_port"></a> [target\_port](#input_target_port) | SSH port used to connect to the target\_host | `number` | `22` | no |
| <a name="input_target_user"></a> [target\_user](#input_target_user) | User to deploy as | `string` | `"root"` | no |
| <a name="input_ssh_options"></a> [ssh\_options](#input_ssh_options) | Additional options to pass to the SSH command | `map(string)` | <pre>{<br> UserKnownHostsFile = "/dev/null"<br> StrictHostKeyChecking = "no"<br>}</pre> | no |

## Outputs

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18 changes: 10 additions & 8 deletions terraform/nixos-rebuild/deploy.sh
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Expand Up @@ -14,14 +14,16 @@ TARGET_PORT=$4
IGNORE_SYSTEMD_ERRORS=$5
shift 3

TARGET="${TARGET_USER}@${TARGET_HOST}"

workDir=$(mktemp -d)
trap 'rm -rf "$workDir"' EXIT

sshOpts=(-p "${TARGET_PORT}")
sshOpts+=(-o UserKnownHostsFile=/dev/null)
sshOpts+=(-o StrictHostKeyChecking=no)
Comment on lines -23 to -24
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This changes the current behavior in nixos-anywhere, if you are not using terraform.

sshConfigFile="$workDir/ssh_config"
cat >"$sshConfigFile" <<EOF
Host $TARGET_HOST
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Yes. As you have rightfully said, this will be an issue for users configuring private ssh keys and jump hosts in their ssh_config.

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Here is a workaround for you specifically, could you not pass in -F in your case instead? terraform also allows to write files, no?

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Maybe we can add support for passing in an ssh config file?

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@threddast threddast Dec 5, 2024 •
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Here is a workaround for you specifically, could you not pass in -F in your case instead? terraform also allows to write files, no?

Yes this would work too. I changed the PR so that additional options are passed as a string to NIX_SSHOPTS

Maybe we can add support for passing in an ssh config file?

I think passing flags is more flexible. As you suggested we can pass -F if a config file is needed

User $TARGET_USER
Port $TARGET_PORT
$(echo "$SSH_OPTIONS" | jq -r 'to_entries[] | " \(.key) \(.value)"')
EOF

set +x
if [[ -n ${SSH_KEY+x} && ${SSH_KEY} != "-" ]]; then
Expand All @@ -32,12 +34,12 @@ if [[ -n ${SSH_KEY+x} && ${SSH_KEY} != "-" ]]; then
echo "$SSH_KEY" >"$sshPrivateKeyFile"
)
unset SSH_AUTH_SOCK # don't use system agent if key was supplied
sshOpts+=(-o "IdentityFile=${sshPrivateKeyFile}")
echo " IdentityFile ${sshPrivateKeyFile}" >>"$sshConfigFile"
fi
set -x

try=1
until NIX_SSHOPTS="${sshOpts[*]}" nix copy -s --experimental-features nix-command --to "ssh://$TARGET" "$NIXOS_SYSTEM"; do
until NIX_SSHOPTS="-F $sshConfigFile" nix copy -s --experimental-features nix-command --to "ssh://$TARGET_HOST" "$NIXOS_SYSTEM"; do
if [[ $try -gt 10 ]]; then
echo "retries exhausted" >&2
exit 1
Expand All @@ -52,7 +54,7 @@ if [[ $TARGET_USER != "root" ]]; then
fi
deploy_status=0
# shellcheck disable=SC2029
ssh "${sshOpts[@]}" "$TARGET" "$switchCommand" || deploy_status="$?"
ssh -F "$sshConfigFile" "$TARGET_HOST" "$switchCommand" || deploy_status="$?"
if [[ $IGNORE_SYSTEMD_ERRORS == "true" && $deploy_status == "4" ]]; then
exit 0
fi
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1 change: 1 addition & 0 deletions terraform/nixos-rebuild/main.tf
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Expand Up @@ -5,6 +5,7 @@ resource "null_resource" "nixos-rebuild" {
provisioner "local-exec" {
environment = {
SSH_KEY = var.ssh_private_key
SSH_OPTIONS = jsonencode(var.ssh_options)
}
command = "${path.module}/deploy.sh ${var.nixos_system} ${var.target_user} ${var.target_host} ${var.target_port} ${var.ignore_systemd_errors}"
}
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9 changes: 9 additions & 0 deletions terraform/nixos-rebuild/variables.tf
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Expand Up @@ -20,6 +20,15 @@ variable "target_port" {
default = 22
}

variable "ssh_options" {
type = map(string)
description = "Additional options to pass to the SSH command"
default = {
UserKnownHostsFile = "/dev/null"
StrictHostKeyChecking = "no"
}
}

variable "ssh_private_key" {
type = string
description = "Content of private key used to connect to the target_host. If set to - no key is passed to openssh and ssh will use its own configuration"
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