oci-containers: move version pinning to JSON file

Container version pinning is currently ad-hoc and spread through various `.nix`
files. Centralise the versions as they should be updated regularly and this
keeps track better. Move it to a `.json` file instead of `.nix` as the fixed
structure will make it easier to manage in future with Renovate.

Test Plan:
```
$ nix eval '.#nixosConfigurations."phoenix.st.ts.hillion.co.uk".config.virtualisation.oci-containers.containers.chia.image'
"ghcr.io/chia-network/chia:2.4.3"
$ nix eval '.#nixosConfigurations."sodium.pop.ts.hillion.co.uk".config.virtualisation.oci-containers.containers.isponsorblocktv.image'
"ghcr.io/dmunozv04/isponsorblocktv:v2.2.1"
```

modules/chia.nix

@@ -45,22 +45,27 @@ in
       uid = config.ids.uids.chia;
     };
 
-    virtualisation.oci-containers.containers.chia = {
-      image = "ghcr.io/chia-network/chia:2.4.3";
-      ports = [ "8444" ];
-      extraOptions = [
-        "--uidmap=0:${toString config.users.users.chia.uid}:1"
-        "--gidmap=0:${toString config.users.groups.chia.gid}:1"
-      ];
-      volumes = [
-        "${cfg.keyFile}:/run/keyfile"
-        "${cfg.path}/.chia:/root/.chia"
-      ] ++ lib.lists.imap0 (i: v: "${v}:/plots${toString i}") cfg.plotDirectories;
-      environment = {
-        keys = "/run/keyfile";
-        plots_dir = lib.strings.concatImapStringsSep ":" (i: v: "/plots${toString i}") cfg.plotDirectories;
+    virtualisation.oci-containers.containers.chia =
+      let
+        imageName = "ghcr.io/chia-network/chia";
+        ver = config.custom.oci-containers.versions."${imageName}";
+      in
+      {
+        image = "${imageName}:${ver}";
+        ports = [ "8444" ];
+        extraOptions = [
+          "--uidmap=0:${toString config.users.users.chia.uid}:1"
+          "--gidmap=0:${toString config.users.groups.chia.gid}:1"
+        ];
+        volumes = [
+          "${cfg.keyFile}:/run/keyfile"
+          "${cfg.path}/.chia:/root/.chia"
+        ] ++ lib.lists.imap0 (i: v: "${v}:/plots${toString i}") cfg.plotDirectories;
+        environment = {
+          keys = "/run/keyfile";
+          plots_dir = lib.strings.concatImapStringsSep ":" (i: v: "/plots${toString i}") cfg.plotDirectories;
+        };
       };
-    };
 
     systemd.tmpfiles.rules = [
       "d ${cfg.path} 0700 chia chia - -"

modules/default.nix

@@ -13,6 +13,7 @@
     ./ids.nix
     ./impermanence.nix
     ./locations.nix
+    ./oci-containers/default.nix
     ./prometheus/default.nix
     ./resilio.nix
     ./sched_ext.nix

modules/oci-containers/default.nix

@@ -0,0 +1,14 @@
+{ config, pkgs, lib, ... }:
+
+{
+  options.custom.oci-containers = {
+    versions = lib.mkOption {
+      description = "oci container versions";
+      readOnly = true;
+    };
+  };
+
+  config = {
+    custom.oci-containers.versions = builtins.fromJSON (builtins.readFile ./versions.json);
+  };
+}

modules/oci-containers/versions.json

@@ -0,0 +1,4 @@
+{
+  "ghcr.io/dmunozv04/isponsorblocktv": "v2.2.1",
+  "ghcr.io/chia-network/chia": "2.4.3"
+}

modules/services/isponsorblocktv.nix

@@ -2,7 +2,9 @@
 
 let
   cfg = config.custom.services.isponsorblocktv;
-  ver = "v2.2.1";
+
+  imageName = "ghcr.io/dmunozv04/isponsorblocktv";
+  ver = config.custom.oci-containers.versions."${imageName}";
 
   ctl = pkgs.writeScriptBin "isponsorblocktv-config" ''
     #! ${pkgs.runtimeShell}
@@ -15,7 +17,7 @@ let
         --uidmap=0:${toString config.users.users.isponsorblocktv.uid}:1 \
         --gidmap=0:${toString config.users.groups.isponsorblocktv.gid}:1 \
         -v ${cfg.dataDir}:/app/data              \
-        ghcr.io/dmunozv04/isponsorblocktv:${ver} \
+        ${imageName}:${ver} \
         --setup-cli
 
     sudo systemctl start podman-isponsorblocktv
@@ -46,7 +48,7 @@ in
     };
 
     virtualisation.oci-containers.containers.isponsorblocktv = {
-      image = "ghcr.io/dmunozv04/isponsorblocktv:${ver}";
+      image = "${imageName}:${ver}";
       extraOptions = [
         "--uidmap=0:${toString config.users.users.isponsorblocktv.uid}:1"
         "--gidmap=0:${toString config.users.groups.isponsorblocktv.gid}:1"