Hi everyone.
I recently starting playing with NixOps with EC2 as a target for hosting some personal servers (to start, a Git remote).
I don’t have a lot of experience administering this kind of infrastructure, so I’m learning as I go.
I encountered a few issues with NixOps. Rather than filing bugs immediately, I wanted to make sure I was on the right track first.
Missing manual contents
I stumbled on to NixOps User's Guide. I started with the VirtualBox example and was able to follow the machine-specific instructions for interacting with EC2.
However, I realized the version of NixOps I had installed was 1.7, so by changing that part of the URL I was able to get an updated manual.
On the other hand, when I search Google for “nixops”, the second result takes me to NixOps User's Guide.
That version of the manual seems to be missing a lot of instructive content. Is it intentional that it’s missing?
Warnings about the cache
(I’ll paste my EC2 configuration file in the next section.)
When I run nixops deploy, at the stage of
gitServer> copying closure...
the process seems to hang for at least 10 minutes and I get 3 to 4 warnings of this form:
gitServer> warning: unable to download 'https://cache.nixos.org/nix-cache-info': Timeout was reached (28); retrying in 307 ms
I’ve seen this consistently over a few days. I noticed some maybe-related issues in the bug-tracker, but (unless I’m mistaken) nothing exactly related.
Is this expected? If not, what can I do to investigate further?
Confusion about attaching EBS volums and NVMe devices
This is the machine configuration file:
let
region = "ca-central-1";
zone = "ca-central-1a";
accessKeyId = "jhaberku";
in
{
resources.ec2KeyPairs.jhaberku = { inherit region accessKeyId; };
gitServer =
{ resources, ... }:
{
deployment.targetEnv = "ec2";
deployment.ec2 = {
inherit accessKeyId region zone;
instanceType = "t3.micro";
ebsInitialRootDiskSize = 3;
elasticIPv4 = "8.8.8.8"; # Not actually.
keyPair = resources.ec2KeyPairs.jhaberku;
securityGroups = ["ssh"];
};
fileSystems."/var/lib/gitolite" = {
fsType = "ext4";
ec2.disk = "vol-foobarbaz"; # Not actually.
device = "/dev/nvme1n1";
};
};
}
I’m a little unclear on the device attribute. My understanding is that this is an assignment that I choose, but one that I have to choose carefully.
When I selected something like /dev/xvdj, I got strange errors (I can reproduce them if it would be helpful).
Then, I noticed the error listed devices of the form /dev/nvme1n1 and I found some documentation for newly-added NVMe device support in NixOps. The documentation contradicted my observation, because it said NVMe devices were not applicable for t3.micro instances, but perhaps that’s changed on AWS’s side now.
I chose what I believe is the next-available “slot” and the deployment proceeded. The device is mounted on the expected point in the file-system, and everything seems to be working.
On the other hand, I consistently get a strange warning when I deploy:
$ nixops deploy
gitServer> warning: device ‘/dev/nvme1n1’ was manually detached!
gitServer> attaching volume ‘vol-foobarbaz’ as ‘/dev/nvme1n1’...
building all machine configurations...
gitServer> copying closure...
jhaberku.net> closures copied successfully
gitServer> updating GRUB 2 menu...
gitServer> activating the configuration...
gitServer> setting up /etc...
gitServer> reloading user units for root...
gitServer> setting up tmpfiles
gitServer> activation finished successfully
jhaberku.net> deployment finished successfully
and nixops check reports issues:
$ nixops check
Machines state:
+-----------+--------+-----+-----------+----------+----------------+------------------------------------+------------------------------------------------------------+
| Name | Exists | Up | Reachable | Disks OK | Load avg. | Units | Notes |
+-----------+--------+-----+-----------+----------+----------------+------------------------------------+------------------------------------------------------------+
| gitServer | Yes | Yes | Yes | No | 0.05 0.03 0.01 | sys-kernel-config.mount [failed] | volume ‘vol-foobarbaz’ not attached to ‘/dev/xvda’ |
| | | | | | | ● tmp.mount [failed] | |
+-----------+--------+-----+-----------+----------+----------------+------------------------------------+------------------------------------------------------------+
Non machines resources state:
+----------+--------+
| Name | Exists |
+----------+--------+
| jhaberku | Yes |
+----------+--------+
What am I doing wrong (if anything)?