35 KiB
title | date | author | series | tags | |||
---|---|---|---|---|---|---|---|
Paranoid NixOS on AWS | 2021-08-11 | Heartmender | nixos |
|
In the last post we covered a lot of the base groundwork involved in making a paranoid NixOS setup. Today we're gonna throw this into prod by making a base NixOS image with it.
At a high level we are going to do the following:
- Pin production OS versions using niv
- Create a script to automatically generate a production-ready NixOS image that you can import into The Cloud
- Manage all this using your favorite buzzwords (Terraform, Infrastructure-as-Code)
- Install an nginx server reverse proxying to the Printer facts service
What is an Image?
Before we yolo this all into prod, let's cover what we're actually doing. There are a lot of conflicting buzzwords here, so I'm going to go out of my way to attempt to simplify them down so that we use my arbitrary definitions of buzzwords instead of what other people will imply they mean. You're reading my blog, you get my buzzwords; it's as simple as that.
In this post we are going to create a base system that you can build your production systems on top of. This base system will be crystallized into an image that AWS will use as the initial starting place for servers.
Yep! The exact steps are a little more complicated but at a high level that's what we're doing.
Base Setup
I'm going to be publishing my work for this post here, but you can follow along in this post to understand the individual steps here.
First, let's set up the environment with lorri and niv. Lorri will handle creating a cached nix-shell environment for us to run things in and niv will handle pinning NixOS to an exact version so you can get a more reproducible production environment.
Set up lorri:
$ lorri init
Aug 11 09:41:50.966 INFO wrote file, path: ./shell.nix
Aug 11 09:41:50.966 INFO wrote file, path: ./.envrc
Aug 11 09:41:50.966 INFO done
direnv: error /home/cadey/code/cadey/paranix-configs/.envrc is blocked. Run `direnv allow` to approve its content
$ direnv allow
direnv: loading ~/code/cadey/paranix-configs/.envrc
Aug 11 09:41:54.581 INFO lorri has not completed an evaluation for this project yet, nix_file: /home/cadey/code/cadey/paranix-configs/shell.nix
direnv: export +IN_NIX_SHELL
Why are you putting the $
before every command in these examples? It looks
extraneous to me.
Set up niv:
$ niv init
Initializing
Creating nix/sources.nix
Creating nix/sources.json
Importing 'niv' ...
Adding package niv
Writing new sources file
Done: Adding package niv
Importing 'nixpkgs' ...
Adding package nixpkgs
Writing new sources file
Done: Adding package nixpkgs
Done: Initializing
$ nix-shell -p niv --run 'niv blah'
And finally pin nixpkgs to a specific version of NixOS.
$ niv update nixpkgs -b nixos-21.05
Update nixpkgs
Done: Update nixpkgs
$
This will become the foundation of our NixOS systems and production images.
You should then set up your shell.nix
to look like this:
let
sources = import ./nix/sources.nix;
pkgs = import sources.nixpkgs { };
in pkgs.mkShell {
buildInputs = with pkgs; [
niv
terraform
bashInteractive
];
};
Set Up Unix Accounts
It's probably important to be able to have access to production machines. Let's
create a NixOS module that will allow you to SSH into the machine. In your
paranix-configs folder, run this command to make a common
config directory:
$ mkdir common
$ cd common
Now in that common directory, open default.nix
in emacs your favorite text
editor and copy in this skeleton:
# common/default.nix
{ config, lib, pkgs, ... }:
{
imports = [ ./users.nix ];
nix.autoOptimiseStore = true;
users.users.root.openssh.authorizedKeys.keys = [ "ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAIPg9gYKVglnO2HQodSJt4z4mNrUSUiyJQ7b+J798bwD9" ];
services.tailscale.enable = true;
# Tell the firewall to implicitly trust packets routed over Tailscale:
networking.firewall.trustedInterfaces = [ "tailscale0" ];
security.auditd.enable = true;
security.audit.enable = true;
security.audit.rules = [
"-a exit,always -F arch=b64 -S execve"
];
security.sudo.execWheelOnly = true;
environment.defaultPackages = lib.mkForce [];
services.openssh = {
passwordAuthentication = false;
allowSFTP = false; # Don't set this if you need sftp
challengeResponseAuthentication = false;
extraConfig = ''
AllowTcpForwarding yes
X11Forwarding no
AllowAgentForwarding no
AllowStreamLocalForwarding no
AuthenticationMethods publickey
'';
};
# PCI compliance
environment.systemPackages = with pkgs; [ clamav ];
}
This will create common
as a folder that can be imported as a NixOS module
with some basic settings and then tells NixOS to try importing users.nix
as a
module. This module doesn't exist yet, so it will fail when we try to import it.
Let's fix that by making users.nix
:
# common/users.nix
{ config, lib, pkgs, ... }:
with lib;
let
# These options will be used for user account defaults in
# the `mkUser` function.
xeserv.users = {
groups = mkOption {
type = types.listOf types.str;
default = [ "wheel" ];
example = ''[ "wheel" "libvirtd" "docker" ]'';
description =
"The Unix groups that Xeserv staff users should be assigned to";
};
shell = mkOption {
type = types.package;
default = pkgs.bashInteractive;
example = "pkgs.powershell";
description =
"The default shell that Xeserv staff users will be given by default.";
};
};
cfg = config.xeserv.users;
mkUser = { keys, shell ? cfg.shell, extraGroups ? cfg.groups, ... }: {
isNormalUser = true;
inherit extraGroups shell;
openssh.authorizedKeys = {
inherit keys;
};
};
in {
options.xeserv.users = xeserv.users;
config.users.users = {
cadey = mkUser {
keys = [ "ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAIPg9gYKVglnO2HQodSJt4z4mNrUSUiyJQ7b+J798bwD9" ];
};
twi = mkUser {
keys = [ "ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAIPYr9hiLtDHgd6lZDgQMkJzvYeAXmePOrgFaWHAjJvNU" ];
};
};
}
Paranoid Settings
Next we're going to set up the paranoid settings from the last post into a
module named paranoid.nix
. First we'll need to grab
impermanence into our niv
manifest like this:
$ niv add nix-community/impermanence
Adding package impermanence
Writing new sources file
Done: Adding package impermanence
Then open common/default.nix
and change this line:
imports = [ ./users.nix ];
To something like this:
imports = [ ./paranoid.nix ./users.nix ];
Then open ./paranoid.nix
in a text editor and paste in the following:
# common/paranoid.nix
{ config, pkgs, lib, ... }:
with lib;
let
sources = import ../nix/sources.nix;
impermanence = sources.impermanence;
cfg = config.xeserv.paranoid;
ifNoexec = if cfg.noexec then [ "noexec" ] else [ ];
in {
imports = [ "${impermanence}/nixos.nix" ];
options.xeserv.paranoid = {
enable = mkEnableOption "enables ephemeral filesystems and limited persistence";
noexec = mkEnableOption "enables every mount on the system save /nix being marked as noexec (potentially dangerous at a social level)";
};
config = mkIf cfg.enable {
fileSystems."/" = mkForce {
device = "none";
fsType = "tmpfs";
options = [ "defaults" "size=2G" "mode=755" ] ++ ifNoexec;
};
fileSystems."/etc/nixos".options = ifNoexec;
fileSystems."/srv".options = ifNoexec;
fileSystems."/var/lib".options = ifNoexec;
fileSystems."/var/log".options = ifNoexec;
fileSystems."/boot" = {
device = "/dev/disk/by-label/boot";
fsType = "vfat";
};
fileSystems."/nix" = {
device = "/dev/disk/by-label/nix";
autoResize = true;
fsType = "ext4";
};
boot.cleanTmpDir = true;
environment.persistence."/nix/persist" = {
directories = [
"/etc/nixos" # nixos system config files, can be considered optional
"/srv" # service data
"/var/lib" # system service persistent data
"/var/log" # the place that journald dumps it logs to
];
};
environment.etc."ssh/ssh_host_rsa_key".source =
"/nix/persist/etc/ssh/ssh_host_rsa_key";
environment.etc."ssh/ssh_host_rsa_key.pub".source =
"/nix/persist/etc/ssh/ssh_host_rsa_key.pub";
environment.etc."ssh/ssh_host_ed25519_key".source =
"/nix/persist/etc/ssh/ssh_host_ed25519_key";
environment.etc."ssh/ssh_host_ed25519_key.pub".source =
"/nix/persist/etc/ssh/ssh_host_ed25519_key.pub";
environment.etc."machine-id".source = "/nix/persist/etc/machine-id";
};
}
This should give us the base that we need to build the system image for AWS.
Building The Image
As I mentioned earlier we need to build a system image before we can build the
image. NixOS normally hides a lot of this magic from you, but we're going to
scrape away all that magic and do this by hand. In your paranix-configs
folder, create a folder named images
. This creatively named folder is where we
will store our NixOS image generation scripts.
Copy this code into build.nix
. This will tell NixOS to create a new system
closure with configuration in images/configuration.nix
:
# images/build.nix
let
sources = import ../nix/sources.nix;
pkgs = import sources.nixpkgs { };
sys = (import "${sources.nixpkgs}/nixos/lib/eval-config.nix" {
system = "x86_64-linux";
modules = [ ./configuration.nix ];
});
in sys.config.system.build.toplevel
And in images/configuration.nix
add this skeleton config:
# images/configuration.nix
{ config, pkgs, lib, modulesPath, ... }:
{
imports = [ ../common (modulesPath + "/virtualisation/amazon-image.nix") ];
xeserv.paranoid.enable = true;
}
You can adapt this to other clouds by changing what module is imported. See the list of available modules here.
Then you can kick off the build with nix-build
:
$ nix-build build.nix
It will take a moment to assemble everything together and when you are done you
should have an entire functional system closure in ./result
:
$ cat ./result/nixos-version
21.05pre-git
From here we need to put this base system closure into a disk image for AWS. This process is a bit more involved, but here are the high level things needed to make a disk image for NixOS (or any Linux system for that matter):
- A virtual hard drive to install the OS to
- A partition mapping on the virtual hard drive
- Essential system files copied over
- A boot configuation
We can model this using a Nix function. This function would need to take in the system config, some metadata about the kind of image to make and then it would build the image and return the result. I've made this available here so you can grab it into your config folder like this:
$ wget -O make-image.nix https://tulpa.dev/cadey/paranix-configs/raw/branch/main/images/make-image.nix
Then we can edit build.nix
to look like this:
# images/build.nix
let
sources = import ../nix/sources.nix;
pkgs = import sources.nixpkgs { };
config = (import "${sources.nixpkgs}/nixos/lib/eval-config.nix" {
system = "x86_64-linux";
modules = [ ./configuration.nix ];
});
in import ./make-image.nix {
inherit (config) config pkgs;
inherit (config.pkgs) lib;
format = "vpc"; # change this for other clouds
}
Then you can build the AWS image with nix-build
:
$ nix-build build.nix
This will emit the AWS disk image in ./result
:
$ ls ./result/
nixos.vhd
Terraforming
Terraform is not my favorite tool on the planet, however it is quite useful for beating AWS and other clouds into shape. We will be using Terraform to do the following:
- Create an S3 bucket to use for storing Terraform states in The Cloud
- Create an S3 bucket for the AMI base images
- Create an IAM role for importing AMIs
- Create an IAM role policy for allowing the AMI importer service to work
- Uploading the image to S3
- Import the image from S3 as an EBS snapshot
- Create an AMI from that EBS snapshot
- Create an example t2.micro virtual machine
- Deploy an example service config for nginx that does nothing
This sounds like a lot, but it's really not as much as it sounds. A lot of this is boilerplate. The cost associated with these steps should be minimal.
In the root of your paranix-configs
folder, make a folder called terraform
,
as this is where our terraform configuration will live:
$ mkdir terraform
$ cd terraform
Then you can proceed to the following steps.
S3 State Bucket
In that folder, make a folder called bootstrap
, this configuration will
contain the base S3 bucket config for Terraform state:
$ mkdir bootstrap
$ cd bootstrap
Copy this terraform code into main.tf
:
# terraform/bootstrap/main.tf
provider "aws" {
region = "us-east-1"
}
resource "aws_s3_bucket" "bucket" {
bucket = "xeserv-tf-state-paranix"
acl = "private"
tags = {
Name = "Terraform State"
}
}
Then run terraform init
to set up the terraform environment:
$ terraform init
It will download the AWS provider and run a few tests on your config to make
sure things are correct. Once this is done, you can run terraform plan
:
$ terraform plan
Terraform used the selected providers to generate the following execution plan. Resource actions
are indicated with the following symbols:
+ create
Terraform will perform the following actions:
# aws_s3_bucket.bucket will be created
+ resource "aws_s3_bucket" "bucket" {
+ acceleration_status = (known after apply)
+ acl = "private"
+ arn = (known after apply)
+ bucket = "xeserv-tf-state-paranoid"
+ bucket_domain_name = (known after apply)
+ bucket_regional_domain_name = (known after apply)
+ force_destroy = false
+ hosted_zone_id = (known after apply)
+ id = (known after apply)
+ region = (known after apply)
+ request_payer = (known after apply)
+ tags = {
+ "Name" = "Terraform State"
}
+ tags_all = {
+ "Name" = "Terraform State"
}
+ website_domain = (known after apply)
+ website_endpoint = (known after apply)
+ versioning {
+ enabled = (known after apply)
+ mfa_delete = (known after apply)
}
}
Plan: 1 to add, 0 to change, 0 to destroy.
Note: You didn't use the -out option to save this plan, so Terraform can't guarantee to take
exactly these actions if you run "terraform apply" now.
Terraform is very pedantic about what the state of the world is. In this case
nothing in the associated state already exists, so it is saying that it needs to
create the S3 bucket that we will use for our Terraform states in the future. We
can apply this with terraform apply
:
$ terraform apply
<the same thing as the plan>
Do you want to perform these actions?
Terraform will perform the actions described above.
Only 'yes' will be accepted to approve.
Enter a value:
If you want to perform these actions, follow the instructions.
Enter a value: yes
aws_s3_bucket.bucket: Creating...
aws_s3_bucket.bucket: Creation complete after 3s [id=xeserv-tf-state-paranoid]
Apply complete! Resources: 1 added, 0 changed, 0 destroyed.
Now that we have the state bucket, let's use it to create our AMI.
Creating the AMI
In your terraform
folder, create a new folder called aws_image
. This is
where the terraform configuration for uploading our disk image to AWS will live.
$ mkdir aws_image
$ cd aws_image
This part of the config is modified from the instructions on how to create an AMI from a locally created VM image here.
Make a file called main.tf
and we'll add to it as we go through this section.
In main.tf
, add the following boilerplate to make the AWS provider use the
terraform state bucket we just created:
# terraform/aws_image/main.tf
provider "aws" {
region = "us-east-1"
}
terraform {
backend "s3" {
bucket = "xeserv-tf-state-paranoid"
key = "aws_image"
region = "us-east-1"
}
}
This will tell the AWS provider to use the S3 bucket we just made, but also to
put the terraform state in a key called aws_image
. We will reuse this state
later for making our printer facts host. After we do this, we should run
terraform init
to make sure that the state bucket is working:
$ terraform init
Initializing the backend...
Initializing provider plugins...
- Finding latest version of hashicorp/aws...
- Installing hashicorp/aws v3.53.0...
- Installed hashicorp/aws v3.53.0 (signed by HashiCorp)
Terraform has created a lock file .terraform.lock.hcl to record the provider
selections it made above. Include this file in your version control repository
so that Terraform can guarantee to make the same selections by default when
you run "terraform init" in the future.
Terraform has been successfully initialized!
You may now begin working with Terraform. Try running "terraform plan" to see
any changes that are required for your infrastructure. All Terraform commands
should now work.
If you ever set or change modules or backend configuration for Terraform,
rerun this command to reinitialize your working directory. If you forget, other
commands will detect it and remind you to do so if necessary.
Now let's create the S3 bucket that we will put our NixOS image in:
# terraform/aws_image/main.tf
resource "aws_s3_bucket" "images" {
bucket = "xeserv-ami-images"
acl = "private"
tags = {
Name = "Xeserv AMI Images"
}
}
Then let's create the IAM role and policy that allows the VM importer service to import objects from S3 into EBS snapshots that we use to create an AMI.
In the aws_image
folder, copy this trust policy statement into
vmie-trust-policy.json
:
{
"Version": "2012-10-17",
"Statement": [
{
"Effect": "Allow",
"Principal": { "Service": "vmie.amazonaws.com" },
"Action": "sts:AssumeRole",
"Condition": {
"StringEquals":{
"sts:Externalid": "vmimport"
}
}
}
]
}
This will be used to give the VM import service permission to act against AWS on your behalf.
In main.tf
, add the following role and policy to the configuration:
# terraform/aws_image/main.tf
resource "aws_iam_role" "vmimport" {
name = "vmimport"
assume_role_policy = file("./vmie-trust-policy.json")
}
resource "aws_iam_role_policy" "vmimport_policy" {
name = "vmimport"
role = aws_iam_role.vmimport.id
policy = <<EOF
{
"Version": "2012-10-17",
"Statement": [
{
"Effect": "Allow",
"Action": [
"s3:ListBucket",
"s3:GetObject",
"s3:GetBucketLocation"
],
"Resource": [
"${aws_s3_bucket.images.arn}",
"${aws_s3_bucket.images.arn}/*"
]
},
{
"Effect": "Allow",
"Action": [
"s3:GetBucketLocation",
"s3:GetObject",
"s3:ListBucket",
"s3:PutObject",
"s3:GetBucketAcl"
],
"Resource": [
"${aws_s3_bucket.images.arn}",
"${aws_s3_bucket.images.arn}/*"
]
},
{
"Effect": "Allow",
"Action": [
"ec2:ModifySnapshotAttribute",
"ec2:CopySnapshot",
"ec2:RegisterImage",
"ec2:Describe*"
],
"Resource": "*"
}
]
}
EOF
}
Why do you define the trust policy in an external file but you have the role policy defined inline?
Look at the Resource
s defined in the Statement
list. The S3 bucket in
question needs to be defined explicitly by its ARN,
and in order to give the vmimport service the minimal possible permissions, we
need to template out that policy JSON file, and doing this inline in Terraform
is a lot simpler.
And now we should run terraform plan
and terraform apply
to make sure
everything works okay:
$ terraform plan
<omitted>
Plan: 3 to add, 0 to change, 0 to destroy.
$ terraform apply
<omitted>
Apply complete! Resources: 3 added, 0 changed, 0 destroyed.
Perfect! Now we need to upload the image to S3. You are going to have to build
the NixOS image outside of terraform, so run nix-build
:
$ nix-build ../../build.nix
This should largely be a no-op and will put the correct result
symlink in your
aws_image
folder so terraform can read the image metadata.
In your main.tf
file, add this:
# terraform/aws_image/main.tf
resource "aws_s3_bucket_object" "nixos_21_05" {
bucket = aws_s3_bucket.images.bucket
key = "nixos-21.05-paranoid.vhd"
source = "./result/nixos.vhd"
etag = filemd5("./result/nixos.vhd")
}
Now we need to create the EBS snapshot. Copy this into your main.tf
:
# terraform/aws_image/main.tf
resource "aws_ebs_snapshot_import" "nixos_21_05" {
disk_container {
format = "VHD"
user_bucket {
s3_bucket = aws_s3_bucket.images.bucket
s3_key = aws_s3_bucket_object.nixos_21_05.key
}
}
role_name = aws_iam_role.vmimport.name
tags = {
Name = "NixOS-21.05"
}
}
This step may take a while (more than 5 minutes), so let's run terraform plan
and then terraform apply
:
$ terraform plan
Plan: 2 to add, 0 to change, 0 to destroy.
$ terraform apply
Apply complete! Resources: 2 added, 0 changed, 0 destroyed.
Finally you can create the AMI and export the AMI ID like this:
# terraform/aws_image/main.tf
resource "aws_ami" "nixos_21_05" {
name = "nixos_21_05"
architecture = "x86_64"
virtualization_type = "hvm"
root_device_name = "/dev/xvda"
ena_support = true
sriov_net_support = "simple"
ebs_block_device {
device_name = "/dev/xvda"
snapshot_id = aws_ebs_snapshot_import.nixos_21_05.id
volume_size = 40 # you can go as low as 8 GB, but 40 is a nice number
delete_on_termination = true
volume_type = "gp3"
}
}
output "nixos_21_05_ami" {
value = aws_ami.nixos_21_05.id
}
Then run terraform plan
and terraform apply
:
$ terraform plan
Plan: 1 to add, 0 to change, 0 to destroy.
$ terraform apply
Apply complete! Resources: 1 added, 0 changed, 0 destroyed.
Outputs:
nixos_21_05_ami = "ami-0f43f74cbbdd1ddef"
Et voila! We have a NixOS base image that we can use for production workloads. Let's use it to create a NixOS server running the printer facts service.
Using the AMI
Let's make a new folder in the terraform
folder called printerfacts
. In this
folder we're going to set up a new terraform state that imports the AMI state we
just made and then we will use that AMI to run the printer facts service.
$ mkdir printerfacts
$ cd printerfacts
In main.tf
, copy the following:
# terraform/printerfacts/main.tf
provider "aws" {
region = "us-east-1"
}
terraform {
backend "s3" {
bucket = "xeserv-tf-state-paranoid"
key = "printerfacts"
region = "us-east-1"
}
}
Now you can terraform init
as normal to ensure everything is working as we
expect:
$ terraform init
Terraform has been successfully initialized!
Then let's add the aws_image
state as a data source. This will let us
reference the AMI ID from the remote state file instead of having to build it
from scratch every time.
# terraform/printerfacts/main.tf
data "terraform_remote_state" "aws_image" {
backend = "s3"
config = {
bucket = "xeserv-tf-state-paranoid"
key = "aws_image"
region = "us-east-1"
}
}
AWS wants us to create a keypair for the instance, so to make AWS happy we will make a keypair like this:
# terraform/printerfacts/main.tf
resource "tls_private_key" "state_ssh_key" {
algorithm = "RSA"
}
resource "aws_key_pair" "generated_key" {
key_name = "generated-key-${sha256(tls_private_key.state_ssh_key.public_key_openssh)}"
public_key = tls_private_key.state_ssh_key.public_key_openssh
}
You will need to terraform init
after this step.
Now we need to create a security group for this instance. This security group should do the following:
- Allow port 22 (ssh) ingress
- Allow port 80 (http) ingress
- Allow ICMP (ping) ingress
- Allow ICMP (ping) egress
- Allow TCP egress on all ports to everywhere
- Allow UDP egress on all ports to everywhere
You can do this with this terraform fragment:
# terraform/printerfacts/main.tf
resource "aws_security_group" "printerfacts" {
ingress {
from_port = 22
to_port = 22
protocol = "tcp"
cidr_blocks = ["0.0.0.0/0"]
}
ingress {
from_port = 80
to_port = 80
protocol = "tcp"
cidr_blocks = ["0.0.0.0/0"]
}
ingress {
from_port = -1
to_port = -1
protocol = "icmp"
cidr_blocks = ["0.0.0.0/0"]
}
egress {
from_port = -1
to_port = -1
protocol = "icmp"
cidr_blocks = ["0.0.0.0/0"]
}
egress {
from_port = 0
to_port = 65535
protocol = "tcp"
cidr_blocks = ["0.0.0.0/0"]
}
egress {
from_port = 0
to_port = 65535
protocol = "udp"
cidr_blocks = ["0.0.0.0/0"]
}
}
Then we can create the AWS instance using our AMI, keypair and security group:
# terraform/printerfacts/main.tf
resource "aws_instance" "printerfacts" {
ami = data.terraform_remote_state.aws_image.outputs.nixos_21_05_ami
instance_type = "t3.micro"
security_groups = [
aws_security_group.printerfacts.name,
]
key_name = aws_key_pair.generated_key.key_name
root_block_device {
volume_size = 40 # GiB
}
tags = {
Name = "xe-printerfacts"
}
}
And then we can create a NixOS deploy config with the fantastic
deploy_nixos
module from Tweag. Copy this into your main.tf
:
# terraform/printerfacts/main.tf
module "deploy_printerfacts" {
source = "git::https://github.com/Xe/terraform-nixos.git//deploy_nixos?ref=1b49f2c6b4e7537cca6dd6d7b530037ea81e8268"
nixos_config = "${path.module}/printerfacts.nix"
hermetic = true
target_user = "root"
target_host = aws_instance.printerfacts.public_ip
ssh_private_key = tls_private_key.state_ssh_key.private_key_pem
ssh_agent = false
build_on_target = false
}
You will need to terraform init
again after this
step.
Now let's make the printerfacts.nix
host definition. We're going to start with
a simple config to begin with. This will start nginx in a mostly broken but
still semi-functional state on port 80.
# terraform/printerfacts/printerfacts.nix
let
sources = import ../../nix/sources.nix;
pkgs = import sources.nixpkgs { };
system = "x86_64-linux";
configuration = { config, lib, pkgs, ... }: {
imports = [
../../common
"${sources.nixpkgs}/nixos/modules/virtualisation/amazon-image.nix"
];
networking.firewall.allowedTCPPorts = [ 22 80 ];
xeserv.paranoid.enable = true;
services.nginx.enable = true;
};
in import "${sources.nixpkgs}/nixos" { inherit system configuration; }
What is up with that config? It doesn't look like a normal NixOS module at all.
Now let's deploy all this and see if it works!
$ terraform init
$ terraform plan
$ terraform apply
Printerfacts Install
Now we can add the printerfacts service to the VM. First, add the printerfacts repo to niv:
$ niv add git -n printerfacts --repo https://tulpa.dev/cadey/printerfacts
Done: Adding package printerfacts
Then create a service definition for it in your common
folder. First create
the folder common/services
:
$ cd ../..
$ cd common
$ mkdir services
$ cd services
Then create a default.nix
file with the following contents:
# common/services/default.nix
{ ... }:
{
imports = [ ./printerfacts.nix ];
}
And create ./printerfacts.nix
with this service boilerplate:
# common/services/printerfacts.nix
{ config, pkgs, lib, ... }:
with lib;
let
sources = import ../../nix/sources.nix;
pkg = pkgs.callPackage sources.printerfacts { };
cfg = config.xeserv.services.printerfacts;
in
{
options.xeserv.services.printerfacts = {
enable = mkEnableOption "enable Printerfacts";
useACME = mkEnableOption "enable ACME certs";
domain = mkOption {
type = types.str;
default = "printerfacts.akua";
example = "printerfacts.cetacean.club";
description =
"The domain name that nginx should check against for HTTP hostnames";
};
port = mkOption {
type = types.int;
default = 28318;
example = 9001;
description =
"The port number printerfacts should listen on for HTTP traffic";
};
};
config = mkIf cfg.enable {
systemd.services.printerfacts = {
wantedBy = [ "multi-user.target" ];
script = ''
export PORT=${toString cfg.port}
export DOMAIN=${toString cfg.domain}
export RUST_LOG=info
exec ${pkg}/bin/printerfacts
'';
serviceConfig = {
Restart = "always";
RestartSec = "30s";
WorkingDirectory = "${pkg}";
RuntimeDirectory = "printerfacts";
RuntimeDirectoryMode = "0755";
StateDirectory = "tailscale";
StateDirectoryMode = "0750";
CacheDirectory = "tailscale";
CacheDirectoryMode = "0750";
DynamicUser = "yes";
};
};
services.nginx.virtualHosts."${cfg.domain}" = {
locations."/" = {
proxyPass = "http://127.0.0.1:${toString cfg.port}";
proxyWebsockets = true;
};
enableACME = cfg.useACME;
};
};
}
Then wire up common/default.nix
with this:
# common/default.nix
imports = [ ./paranoid.nix ./users.nix ./services ];
Then you can add this to your machine config in the terraform directory:
# terraform/printerfacts/printerfacts.nix
configuration = { config, lib, pkgs, ... }: {
# ...
xeserv.services.printerfacts = {
enable = true;
domain = "3.237.88.228"; # replace this with the IP of your AWS instance
};
};
Then terraform plan
and terraform apply
:
$ terraform plan
$ terraform apply
And finally get yourself a hard-earned printer fact:
$ curl http://3.237.88.228/fact
In 1987 printers overtook scanners as the number one pet in America.
We have gone from nothing to a fully production-ready NixOS deployment including a custom AMI pinned to an exact version of NixOS and an additional service added from its git repo. This will allow you to create a NixOS deployment that can be used by multiple people but will also stay pinned to an exact version of NixOS. Terraform will do all of the NixOS building and ensure that things are kept up to date, meaning that your infrastructure is all configured using the same workflow.
This post outlines boilerplate and templates. I'm sure that you could easily
adapt these templates for other things as well. If you need to store persistent
data, make sure its being put in /var/lib
so that it isn't wiped on reboot.
This took at least a week of research, banging my head against the wall and so
many failures to implement this. Many thanks to Graham
Christensen for unblocking me on this and pulling me
back from the chasm a few times.
Hope this helps your prod NixOS adventures!