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gce/fetch-ssh-keys: Put script in separate file, use PrivateTmp...

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...check the script with shfmt and shellcheck + some other minor
refactoring.
This commit is contained in:
talyz 2021-02-11 21:16:51 +01:00
parent dd6ebb7871
commit 95f96de78e
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GPG Key ID: 2DED2151F4671A2B
2 changed files with 51 additions and 53 deletions
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36
nixos/modules/virtualisation/fetch-instance-ssh-keys.bash Normal file
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@ -0,0 +1,36 @@
#!/usr/bin/env bash
set -euo pipefail
WGET() {
wget --retry-connrefused -t 15 --waitretry=10 --header='Metadata-Flavor: Google' "$@"
}
# When dealing with cryptographic keys, we want to keep things private.
umask 077
mkdir -p /root/.ssh
echo "Fetching authorized keys..."
WGET -O /tmp/auth_keys http://metadata.google.internal/computeMetadata/v1/instance/attributes/sshKeys
# Read keys one by one, split in case Google decided
# to append metadata (it does sometimes) and add to
# authorized_keys if not already present.
touch /root/.ssh/authorized_keys
while IFS='' read -r line || [[ -n "$line" ]]; do
keyLine=$(echo -n "$line" | cut -d ':' -f2)
IFS=' ' read -r -a array <<<"$keyLine"
if [[ ${#array[@]} -ge 3 ]]; then
echo "${array[@]:0:3}" >>/tmp/new_keys
echo "Added ${array[*]:2} to authorized_keys"
fi
done </tmp/auth_keys
mv /tmp/new_keys /root/.ssh/authorized_keys
chmod 600 /root/.ssh/authorized_keys
echo "Fetching host keys..."
WGET -O /tmp/ssh_host_ed25519_key http://metadata.google.internal/computeMetadata/v1/instance/attributes/ssh_host_ed25519_key
WGET -O /tmp/ssh_host_ed25519_key.pub http://metadata.google.internal/computeMetadata/v1/instance/attributes/ssh_host_ed25519_key_pub
mv -f /tmp/ssh_host_ed25519_key* /etc/ssh/
chmod 600 /etc/ssh/ssh_host_ed25519_key
chmod 644 /etc/ssh/ssh_host_ed25519_key.pub

68
nixos/modules/virtualisation/google-compute-config.nix
View File

@ -69,67 +69,29 @@ in
# GC has 1460 MTU
networking.interfaces.eth0.mtu = 1460;
systemd.services.fetch-ssh-keys = {
# Used by NixOps
systemd.services.fetch-instance-ssh-keys = {
description = "Fetch host keys and authorized_keys for root user";
wantedBy = [ "sshd.service" ];
before = [ "sshd.service" ];
after = [ "network-online.target" ];
wants = [ "network-online.target" ];
path = [ pkgs.wget ];
script =
let
wget = "${pkgs.wget}/bin/wget --retry-connrefused -t 15 --waitretry=10 --header='Metadata-Flavor: Google'";
mktemp = "mktemp --tmpdir=/run";
in ''
# When dealing with cryptographic keys, we want to keep things private.
umask 077
mkdir -m 0700 -p /root/.ssh
echo "Obtaining SSH keys..."
AUTH_KEYS=$(${mktemp})
${wget} -O $AUTH_KEYS http://metadata.google.internal/computeMetadata/v1/instance/attributes/sshKeys
if [ -s $AUTH_KEYS ]; then
# Read in key one by one, split in case Google decided
# to append metadata (it does sometimes) and add to
# authorized_keys if not already present.
touch /root/.ssh/authorized_keys
NEW_KEYS=$(${mktemp})
# Yes this is a nix escape of two single quotes.
while IFS=''' read -r line || [[ -n "$line" ]]; do
keyLine=$(echo -n "$line" | cut -d ':' -f2)
IFS=' ' read -r -a array <<< "$keyLine"
if [ ''${#array[@]} -ge 3 ]; then
echo ''${array[@]:0:3} >> $NEW_KEYS
echo "Added ''${array[@]:2} to authorized_keys"
fi
done < $AUTH_KEYS
mv $NEW_KEYS /root/.ssh/authorized_keys
chmod 600 /root/.ssh/authorized_keys
rm -f $KEY_PUB
else
echo "Downloading http://metadata.google.internal/computeMetadata/v1/project/attributes/sshKeys failed."
false
fi
rm -f $AUTH_KEYS
SSH_HOST_KEYS_DIR=$(${mktemp} -d)
${wget} -O $SSH_HOST_KEYS_DIR/ssh_host_ed25519_key http://metadata.google.internal/computeMetadata/v1/instance/attributes/ssh_host_ed25519_key
${wget} -O $SSH_HOST_KEYS_DIR/ssh_host_ed25519_key.pub http://metadata.google.internal/computeMetadata/v1/instance/attributes/ssh_host_ed25519_key_pub
if [ -s $SSH_HOST_KEYS_DIR/ssh_host_ed25519_key -a -s $SSH_HOST_KEYS_DIR/ssh_host_ed25519_key.pub ]; then
mv -f $SSH_HOST_KEYS_DIR/ssh_host_ed25519_key* /etc/ssh/
chmod 600 /etc/ssh/ssh_host_ed25519_key
chmod 644 /etc/ssh/ssh_host_ed25519_key.pub
else
echo "Setup of ssh host keys from http://metadata.google.internal/computeMetadata/v1/instance/attributes/ failed."
false
fi
rm -rf $SSH_HOST_KEYS_DIR
serviceConfig = {
Type = "oneshot";
ExecStart = pkgs.runCommand "fetch-instance-ssh-keys" { } ''
cp ${./fetch-instance-ssh-keys.bash} $out
chmod +x $out
${pkgs.shfmt}/bin/shfmt -i 4 -d $out
${pkgs.shellcheck}/bin/shellcheck $out
patchShebangs $out
'';
serviceConfig.Type = "oneshot";
serviceConfig.RemainAfterExit = true;
serviceConfig.StandardError = "journal+console";
serviceConfig.StandardOutput = "journal+console";
PrivateTmp = true;
StandardError = "journal+console";
StandardOutput = "journal+console";
};
};
systemd.services.google-instance-setup = {