agenix/modules/age.nix

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{ config, options, lib, pkgs, ... }:
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with lib;
let
cfg = config.age;
# we need at least rage 0.5.0 to support ssh keys
rage =
if lib.versionOlder pkgs.rage.version "0.5.0"
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then pkgs.callPackage ../pkgs/rage.nix { }
else pkgs.rage;
ageBin = "${rage}/bin/rage";
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users = config.users.users;
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identities = builtins.concatStringsSep " " (map (path: "-i ${path}") cfg.sshKeyPaths);
installSecret = secretType: ''
${if secretType.symlink then ''
_truePath="${cfg.secretsMountPoint}/$_agenix_generation/${secretType.name}"
'' else ''
_truePath="${secretType.path}"
''}
echo "decrypting '${secretType.file}' to '$_truePath'..."
TMP_FILE="$_truePath.tmp"
mkdir -p "$(dirname "$_truePath")"
mkdir -p "$(dirname "${secretType.path}")"
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(
umask u=r,g=,o=
LANG=${config.i18n.defaultLocale} ${ageBin} --decrypt ${identities} -o "$TMP_FILE" "${secretType.file}"
)
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chmod ${secretType.mode} "$TMP_FILE"
chown ${secretType.owner}:${secretType.group} "$TMP_FILE"
mv -f "$TMP_FILE" "$_truePath"
${optionalString secretType.symlink ''
[ "${secretType.path}" != "/run/agenix/${secretType.name}" ] && ln -sfn "/run/agenix/${secretType.name}" "${secretType.path}"
''}
'';
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isRootSecret = st: (st.owner == "root" || st.owner == "0") && (st.group == "root" || st.group == "0");
isNotRootSecret = st: !(isRootSecret st);
rootOwnedSecrets = builtins.filter isRootSecret (builtins.attrValues cfg.secrets);
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installRootOwnedSecrets = builtins.concatStringsSep "\n" ([ "echo '[agenix] decrypting root secrets...'" ] ++ (map installSecret rootOwnedSecrets));
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nonRootSecrets = builtins.filter isNotRootSecret (builtins.attrValues cfg.secrets);
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installNonRootSecrets = builtins.concatStringsSep "\n" ([ "echo '[agenix] decrypting non-root secrets...'" ] ++ (map installSecret nonRootSecrets));
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secretType = types.submodule ({ config, ... }: {
options = {
name = mkOption {
type = types.str;
default = config._module.args.name;
description = ''
Name of the file used in /run/agenix
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'';
};
file = mkOption {
type = types.path;
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description = ''
Age file the secret is loaded from.
'';
};
path = mkOption {
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type = types.str;
default = "/run/agenix/${config.name}";
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description = ''
Path where the decrypted secret is installed.
'';
};
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mode = mkOption {
type = types.str;
default = "0400";
description = ''
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Permissions mode of the decrypted secret in a format understood by chmod.
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'';
};
owner = mkOption {
type = types.str;
default = "0";
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description = ''
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User of the decrypted secret.
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'';
};
group = mkOption {
type = types.str;
default = users.${config.owner}.group or "0";
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description = ''
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Group of the decrypted secret.
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'';
};
symlink = mkEnableOption "symlinking secrets to their destination" // { default = true; };
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};
});
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in
{
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options.age = {
secrets = mkOption {
type = types.attrsOf secretType;
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default = { };
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description = ''
Attrset of secrets.
'';
};
secretsMountPoint = mkOption {
type = types.addCheck types.str
(s:
(builtins.match "[ \t\n]*" s) == null # non-empty
&& (builtins.match ".+/" s) == null) # without trailing slash
// { description = "${types.str.description} (with check: non-empty without trailing slash)"; };
default = "/run/agenix.d";
description = ''
Where secrets are created before they are symlinked to /run/agenix
'';
};
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sshKeyPaths = mkOption {
type = types.listOf types.path;
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default =
if config.services.openssh.enable then
map (e: e.path) (lib.filter (e: e.type == "rsa" || e.type == "ed25519") config.services.openssh.hostKeys)
else [ ];
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description = ''
Path to SSH keys to be used as identities in age decryption.
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'';
};
};
config = mkIf (cfg.secrets != { }) {
assertions = [{
assertion = cfg.sshKeyPaths != [ ];
message = "age.sshKeyPaths must be set.";
}];
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# Create a new directory full of secrets for symlinking (this helps
# ensure removed secrets are actually removed, or at least become
# invalid symlinks).
system.activationScripts.agenixMountSecrets = ''
_agenix_generation="$(basename "$(readlink /run/agenix)" || echo 0)"
(( ++_agenix_generation ))
echo "[agenix] symlinking new secrets to /run/agenix (generation $_agenix_generation)..."
mkdir -p "${cfg.secretsMountPoint}"
chmod 0751 "${cfg.secretsMountPoint}"
grep -q "${cfg.secretsMountPoint} ramfs" /proc/mounts || mount -t ramfs none "${cfg.secretsMountPoint}" -o nodev,nosuid,mode=0751
mkdir -p "${cfg.secretsMountPoint}/$_agenix_generation"
chmod 0751 "${cfg.secretsMountPoint}/$_agenix_generation"
ln -sfn "${cfg.secretsMountPoint}/$_agenix_generation" /run/agenix
(( _agenix_generation > 1 )) && {
echo "[agenix] removing old secrets (generation $(( _agenix_generation - 1 )))..."
rm -rf "${cfg.secretsMountPoint}/$(( _agenix_generation - 1 ))"
}
'';
# Secrets with root owner and group can be installed before users
# exist. This allows user password files to be encrypted.
system.activationScripts.agenixRoot = {
text = installRootOwnedSecrets;
deps = [ "agenixMountSecrets" "specialfs" ];
};
system.activationScripts.users.deps = [ "agenixRoot" ];
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# chown the secrets mountpoint and the current generation to the keys group
# instead of leaving it root:root.
system.activationScripts.agenixChownKeys = {
text = ''
chown :keys "${cfg.secretsMountPoint}" "${cfg.secretsMountPoint}/$_agenix_generation"
'';
deps = [
"users"
"groups"
"agenixMountSecrets"
];
};
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# Other secrets need to wait for users and groups to exist.
system.activationScripts.agenix = {
text = installNonRootSecrets;
deps = [
"users"
"groups"
"specialfs"
"agenixMountSecrets"
"agenixChownKeys"
];
};
};
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}