Use sops for private key distribution

.sops.yaml

@@ -1,6 +1,6 @@
 keys:
   - &nerf age1rasjnr2tlv9y70sj0z0hwpgpxdc974wzg5umtx2pnc6z0p05u3js6r8sln
-  - &gonne age1xv5rfxkxg9jyqx5jg2j82cxv7w7ep4a3795p4yl5fuqf38f3m3eqfnefju
+  - &gonne age1epz92k2rkp43hkrg3u0jgkzhnkwx8y43kag7rvfzwl9wcddelvusyetxl7
 
   - &nyarlathotep age1s99d0vlj5qlm287n98jratql5fypvjrxxal0k5jl2aw9dcc8kyvqw5yyt4
   - &bragi age1lqvgpmlemyg9095ujck64u59ma29656zs7a4yxgz4s6u5cld2ccss69jwe

nixos/machines/bragi/backupKey.yaml

@@ -0,0 +1,39 @@
+backupKey: ENC[AES256_GCM,data:PBdeV6uQ/Jg9xk7HXylyDKCBdny/XRflF752arUZAnUvmVv4yiSwOY9ua3tH1BDpddiql1aNJqmfatZOB3JKB2mHnyeSt7L0B81zuIFpxJOdsnGACviH6sUfsC5ogkGRhLKynf5Ghz/6xanthyK6euIpAAu05wDWcseg4y8k5rdFhL7rasmOMi0oVLN54Psmyf9vahfX6BNGBHQA1qJyeaI5iDLI+6gh7dtOXjTd4pHX8T9PEYpGnOBMHvaaVA2r7z27iUJSKqzzSB9B/rm01tI6LTG/yfQU+TKlWFU2iIodCG7eJ2qe+exvxOlEj9At/UI/Kd+dNSHcffLDUxVcstthOOP0TUdHkPCTC8BEJtAAexUBqSv+LTOPfJeAbIw3QhEpfeyZOpw2FY1qstQ/G0+1sDF8762uJu9v1amx4+4e8NEiSa/dtdnQAKFiEswk+5nqRSKQJOH3w0tHr9NRhhS775lUtUX4DW0xN42QeABM0xg56qJPxPNif3K2ovPX3BTSSZnQ0EZzuxployu1MyJxpcBT+6qa8l/h,iv:ZdivBorDtIyBOs7XSg/DHjReG+T6/exeS8ziA7ms7FM=,tag:gcIXgpyd2UeQV3APqCCxMg==,type:str]
+sops:
+    kms: []
+    gcp_kms: []
+    azure_kv: []
+    hc_vault: []
+    age:
+        - recipient: age1rasjnr2tlv9y70sj0z0hwpgpxdc974wzg5umtx2pnc6z0p05u3js6r8sln
+          enc: |
+            -----BEGIN AGE ENCRYPTED FILE-----
+            YWdlLWVuY3J5cHRpb24ub3JnL3YxCi0+IFgyNTUxOSBaR2dRc3NPeUwwaHdCL25V
+            RHNaWU9xRUw5dDlaOG5hczVlNm5UR01QUEVNClJsVFRBWU85Z0JuV1l3MDdvd1F2
+            RS9CcXhuNEJWdEE1cktXYjF3RW9wUDQKLS0tIHk3MURmWlJNanVZaHlUR3R2UEZG
+            K2JxOHpNY2hsTysrWjNLajFKQkxuNHcKaFMvnDt9a3HsnbP1Q/i4ifRIXFcXYn8z
+            YyOho0hSmWZNhTbltmuVKjvCNgt9ONVRW93uRDDoju8Odps0qwwvuA==
+            -----END AGE ENCRYPTED FILE-----
+        - recipient: age1epz92k2rkp43hkrg3u0jgkzhnkwx8y43kag7rvfzwl9wcddelvusyetxl7
+          enc: |
+            -----BEGIN AGE ENCRYPTED FILE-----
+            YWdlLWVuY3J5cHRpb24ub3JnL3YxCi0+IFgyNTUxOSBMM1NCbHdFZDJvYjJjcmZ6
+            bUFjSG5OUEdydS9pTkNHRjFKb3gvWll0Q0RVCk56ZnhDa0NGeUNhVVdDZENieDFW
+            Q0xSNXhYQXZSVnI3WlRzUjhxOXRyM2sKLS0tIGhnVWJaRG4vSGpUcnQ5SFVFT3VQ
+            YUFzTlNLSE9CbW9oYTFsY0tpTE4vZTQKjurd87tDH8z58pAGJyVXRAu8Q2+k7e4G
+            zOGZhm5DpSmFv2O2fqXgBg8nT5wrPKQDFvcDh1P+a0753tUTbUttIA==
+            -----END AGE ENCRYPTED FILE-----
+        - recipient: age1lqvgpmlemyg9095ujck64u59ma29656zs7a4yxgz4s6u5cld2ccss69jwe
+          enc: |
+            -----BEGIN AGE ENCRYPTED FILE-----
+            YWdlLWVuY3J5cHRpb24ub3JnL3YxCi0+IFgyNTUxOSBlWmlwS0E5TytFdEpxN09U
+            Y3k0SDhnM2h5Rnh1bXQ2czA5bWt1Mkk3aUFFCmtwT2ZmN0IweGdOYURWNDVHcWtH
+            R3lRaFRkcWYzb2g4NWNFQU5WOXZZaGMKLS0tIHpWNnNvVUNucE5MQ1cxQWl6Qm1x
+            NUZDVnJORXF1NGlyNUkzOGl2REFHdmsK18k9UfOmtFSep6mZcSp6di7SjvrBXgGp
+            oWtLehp1UFEHCgaU5YxlYhtkrrOhb8ykFb1on+kmzrloaHqyvks7Aw==
+            -----END AGE ENCRYPTED FILE-----
+    lastmodified: "2024-03-21T16:38:08Z"
+    mac: ENC[AES256_GCM,data:kEVWd988Ia6T8v3w0slQhM0lh78VhnP8qJNa6IZg0NF2B0JQbFRnQNbUfvG9Rf4mkAR/O9PD+r6HR+b3LCwzb/Ok/eD4/M3+oPaEx/JnoHrzF/1N29VEAvBHjQgw6DL05toqu5G03UDcDUFGc111AeRsexhONQRHJx3zqWyWGy4=,iv:T5Pkhl3vhSAIoKkC3r3VQn3tC4t04WxvAZDQ4PMvD84=,tag:h0/aB91SFr5q0Or5daxWUQ==,type:str]
+    pgp: []
+    unencrypted_suffix: _unencrypted
+    version: 3.8.1

nixos/modules/borgbackup.nix

@@ -116,12 +116,12 @@ in {
       jobs.fsaccount = {
         preHook = ''
           mkdir -p /home/fsaccount/sicherung # Create if it does not exist
-          ${pkgs.rsync}/bin/rsync -e 'ssh -i /home/fsaccount/.ssh/fsaccount' -r fachschaft@gw1.mathematik.tu-darmstadt.de:/home/fachschaft/* /home/fsaccount/sicherung
+          ${pkgs.rsync}/bin/rsync -e 'ssh -i /run/secrets/backupKey' -r fachschaft@gw1.mathematik.tu-darmstadt.de:/home/fachschaft/* /home/fsaccount/sicherung
         '';
         paths = "/home/fsaccount/sicherung";
         encryption.mode = "none";
         environment = {
-          BORG_RSH = "ssh -i /home/fsaccount/.ssh/fsaccount";
+          BORG_RSH = "ssh -i /run/secrets/backupKey";
           BORG_UNKNOWN_UNENCRYPTED_REPO_ACCESS_IS_OK = "yes";
         };
         repo = "borg@localhost:fsaccount";
@@ -132,13 +132,23 @@ in {
       };
     };
     environment.persistence.${config.impermanence.name} = {
-      users.fsaccount.directories = [
+      users.fsaccount.files = [
         {
-          directory = ".ssh"; # SSH Key with access to FS Account and known_hosts
+          file = ".ssh/known_hosts";
-          mode = "u=rwx,g=,o=";
+          parentDirectory = {
+            mode = "u=rwx,g=,o=";
+            user = "fsaccount";
+            group = "users";
+          };
         }
       ];
     };
+    sops.secrets.backupKey = {
+      sopsFile = ../machines/bragi/backupKey.yaml;
+      owner = config.users.users.fsaccount.name;
+      inherit (config.users.users.fsaccount) group;
+      mode = "0400";
+    };
     # Extra user for FS account backup
     users.users = {
       fsaccount = {