Merge pull request #957 from obsidiansystems/deploy-reboot-logic

Determine whether a reboot is necessary when deploying, and take the appropriate action

ChangeLog.md

@@ -25,6 +25,7 @@ This project's release branch is `master`. This log is written from the perspect
   * [#915](https://github.com/obsidiansystems/obelisk/pull/915): Add routeLinkAttr to Obelisk.Route.Frontend. This allows the creation of route links with additional, user-specified attributes.
   * [#918](https://github.com/obsidiansystems/obelisk/pull/918): Add GHC 8.10.7 support for `obelisk-route`
   * [#952](https://github.com/obsidiansystems/obelisk/pull/952): Add a `Semigroupoid` instance for the `Encoder` type, compatible with its existing `Category` instance.
+  * [#957](https://github.com/obsidiansystems/obelisk/pull/957): ob deploy will now detect when the target machine needs to be rebooted after deployment and automatically do so. This is necessary, for example, when the kernel has been updated.
 * Javascript FFI
   * [#844](https://github.com/obsidiansystems/obelisk/pull/844): Jsaddle FFI example extended in skeleton (example project which is installed by `ob init`). Note the remark on minifier renaming in /skeleton/static/lib.js
   * [#903](https://github.com/obsidiansystems/obelisk/pull/903): Added support for a file which allows users to specify global variables and namespaces in JS, that should not be used by the Google Closure Compiler during minification of the GHCJS produced JS. See the [FAQ](FAQ.md).

lib/command/src/Obelisk/Command/Deploy.hs

@@ -224,10 +224,8 @@ deployPush deployPath builders = do
       proc sshPath $ sshOpts <>
         [ "root@" <> host
         , unwords
-            -- Note that we don't want to $(staticWhich "nix-env") here, because this is executing on a remote machine
-            [ "nix-env -p /nix/var/nix/profiles/system --set " <> outputPath
-            , "&&"
-            , "/nix/var/nix/profiles/system/bin/switch-to-configuration switch"
+            [ "bash -c"
+            , bashEscape (deployActivationScript outputPath)
             ]
         ]
   isClean <- checkGitCleanStatus deployPath True
@@ -243,6 +241,30 @@ deployPush deployPath builders = do
       let p = setEnvOverride (envMap <>) $ setDelegateCtlc True $ proc cmd args
       callProcessAndLogOutput (Notice, Notice) p
 
+-- | Bash command that will be run on the deployed machine to actually switch the NixOS configuration
+-- This has some more involved logic than merely activating the right profile. It also determines
+-- whether the kernel parameters have changed so that the deployed NixOS instance should be restarted.
+deployActivationScript
+  :: String
+  -- ^ The out path of the configuration to activate
+  -> String
+deployActivationScript outPath =
+-- Note that we don't want to $(staticWhich "nix-env") here, because this is executing on a remote machine
+-- This logic follows the nixos auto-upgrade module as of writing.
+-- If the workflow is added to switch-to-configuration proper, we can simplify this:
+-- https://github.com/obsidiansystems/obelisk/issues/958
+  [i|set -euxo pipefail
+nix-env -p /nix/var/nix/profiles/system --set "${bashEscape outPath}"
+/nix/var/nix/profiles/system/bin/switch-to-configuration boot
+booted="$(readlink /run/booted-system/{initrd,kernel,kernel-modules})"
+built="$(readlink /nix/var/nix/profiles/system/{initrd,kernel,kernel-modules})"
+if [ "$booted" = "$built" ]; then
+  /nix/var/nix/profiles/system/bin/switch-to-configuration switch
+else
+  /run/current-system/sw/bin/shutdown -r +1
+fi
+|]
+
 -- | Update the source thunk in the staging directory to the HEAD of the branch.
 deployUpdate :: MonadObelisk m => FilePath -> m ()
 deployUpdate deployPath = updateThunkToLatest (ThunkUpdateConfig Nothing (ThunkConfig Nothing)) (deployPath </> "src")