Merge pull request #119 from hercules-ci/nixos-21.05-podman-preparation

Add NixOS 21.05 to ci.nix

.envrc

@@ -1,4 +1,6 @@
+HOST_XDG_DATA_DIRS="${XDG_DATA_DIRS:-}"
 eval "$(lorri direnv)"
+export XDG_DATA_DIRS="${XDG_DATA_DIRS}:${HOST_XDG_DATA_DIRS}"
 
 # Use system PKI
 unset SSL_CERT_FILE

docs/modules/ROOT/pages/index.adoc

@@ -61,11 +61,18 @@ Add this module to your NixOS configuration:
 { pkgs, ... }: {
   environment.systemPackages = [
     pkgs.arion
-    pkgs.docker # docker CLI will use podman socket
+
+     # Do install the docker CLI to talk to podman.
+     # Not needed when virtualisation.docker.enable = true;
+    pkgs.docker-client
   ];
+
+  # Arion works with Docker, but for NixOS-based containers, you need Podman
+  # since NixOS 21.05.
   virtualisation.docker.enable = false;
   virtualisation.podman.enable = true;
   virtualisation.podman.dockerSocket.enable = true;
+  virtualisation.podman.defaultNetwork.dnsname.enable = true;
 
   # Use your username instead of `myuser`
   users.extraUsers.myuser.extraGroups = ["podman"];
@@ -125,16 +132,13 @@ Describe containers using NixOS-style modules. There are a few options:
     };
   };
 }
-
-
 ```
 
 ==== NixOS: run only one systemd service
 
 `examples/nixos-unit/arion-compose.nix`:
 
 ```nix
-
 {
   services.webserver = { config, pkgs, ... }: {
 
@@ -157,7 +161,6 @@ Describe containers using NixOS-style modules. There are a few options:
     ];
   };
 }
-
 ```
 
 ==== NixOS: run full OS
@@ -220,10 +223,10 @@ development environments while working on
 https://www.hercules-ci.com[Hercules CI]. (It was also born out of
 ancient Greek deities disguised as horses. More on that later.)
 
-If you do want to use Arion for production environments, you’ll probably
-want to either build normal container images or manage garbage
-collection roots if you control the deployment host. Neither scenario is
-made easier by arion at this time.
+Arion can be used for simple single host deployments, using Docker's TLS
+client verification, or https://search.nixos.org/options?channel=unstable&show=virtualisation.podman.networkSocket.enable&query=virtualisation.podman[`virtualisation.podman.networkSocket` options].
+Remote deployments do not support `useHostStore`, although an SSH-based deployment method could support this.
+Docker Swarm is not currently supported.
 
 Arion has run successfully on Linux distributions other than NixOS, but we only perform CI for Arion on NixOS.
 
@@ -254,6 +257,8 @@ container.
 
 Nope, it’s just Nix and Docker Compose under the hood.
 
+It does xref:hercules-ci-effects:ROOT:reference/nix-functions/runArion.adoc[integrate] nicely though.
+
 === What about garbage collection?
 
 Arion removes the need for garbage collecting docker images, delegating
@@ -266,8 +271,9 @@ generate images that can be used in production.
 
 === Why is my container not running latest code?
 
-Restart it with `arion restart <name>` or if you've changed the image rebuild
-them using `arion up -d --always-recreate-deps <name>`.
+Rebuild the image using `arion up -d --always-recreate-deps <name>` or simply `arion up -d`.
+
+Like `docker-compose restart`, `arion restart` does not update the image before starting.
 
 === What is messing with my environment variables?
 
@@ -278,11 +284,11 @@ reference a script from `pkgs.writeScript` or escape the dollar sign as
 
 === Why name it ``Arion``?
 
-Arion comes from Greek mythology. Poseidon, the god of ~Docker~ the seas
+Arion comes from Greek mythology. Poseidon, the god of Docker -- I mean the seas --
 had his eye on Demeter. Demeter tried to trick him by disguising as a
 horse, but Poseidon saw through the deception and they had Arion.
 
 So Arion is a super fast divine horse; the result of some weird mixing.
 Also it talks.
 
-(And we feel morally obliged to name our stuff after Greek mythology)
+(And we felt morally obliged to name our stuff after Greek mythology)

nix/ci.nix

@@ -12,6 +12,10 @@ dimension "Nixpkgs version" {
       dockerSupportsSystemd = true;
       nixosHasPodmanDockerSocket = false;
     };
+    "nixos-21_05" = {
+      nixpkgsSource = "nixos-21.05";
+      enableDoc = true;
+    };
     "nixos-unstable" = {
       nixpkgsSource = "nixos-unstable";
       enableDoc = true;

nix/sources.json

@@ -23,6 +23,18 @@
         "url": "https://github.com/NixOS/nixpkgs/archive/0cfe5377e8993052f9b0dd56d058f8008af45bd9.tar.gz",
         "url_template": "https://github.com/<owner>/<repo>/archive/<rev>.tar.gz"
     },
+    "nixos-21.05": {
+        "branch": "nixos-21.05",
+        "description": "Nix Packages collection",
+        "homepage": null,
+        "owner": "NixOS",
+        "repo": "nixpkgs",
+        "rev": "297970378b9437541c065f3fef26871397edd2d4",
+        "sha256": "1q5dnylr4w1xqn3qxx7hn0pn01pcwdmsy70cjs01dn8b50ppc93g",
+        "type": "tarball",
+        "url": "https://github.com/NixOS/nixpkgs/archive/297970378b9437541c065f3fef26871397edd2d4.tar.gz",
+        "url_template": "https://github.com/<owner>/<repo>/archive/<rev>.tar.gz"
+    },
     "nixos-unstable": {
         "branch": "master",
         "description": "A read-only mirror of NixOS/nixpkgs tracking the released channels. Send issues and PRs to",