install: Add print-configuration

Even when an external process is creating the disk, we want
it to be able to honor the root filesystem type specified in the container.

Signed-off-by: Colin Walters <walters@verbum.org>

.github/workflows/ci.yml

@@ -106,7 +106,7 @@ jobs:
     name: "Container testing"
     needs: build-fedora
     runs-on: ubuntu-latest
-    container: quay.io/fedora/fedora-coreos:testing-devel
+    container: quay.io/centos-bootc/fedora-bootc:eln
     steps:
       - name: Download
         uses: actions/download-artifact@v3

lib/src/cli.rs

@@ -118,6 +118,13 @@ pub(crate) enum InstallOpts {
     ToDisk(crate::install::InstallToDiskOpts),
     /// Install to the target filesystem
     ToFilesystem(crate::install::InstallToFilesystemOpts),
+    /// Output JSON to stdout that contains the merged installation configuration
+    /// as it may be relevant to calling processes using `install to-filesystem`
+    /// that want to honor e.g. `root-fs-type`.
+    ///
+    /// At the current time, the only output key is `root-fs-type` which is a string-valued
+    /// filesystem name
+    PrintConfiguration,
 }
 
 /// Options for man page generation
@@ -522,6 +529,7 @@ async fn run_from_opt(opt: Opt) -> Result<()> {
         Opt::Install(opts) => match opts {
             InstallOpts::ToDisk(opts) => crate::install::install_to_disk(opts).await,
             InstallOpts::ToFilesystem(opts) => crate::install::install_to_filesystem(opts).await,
+            InstallOpts::PrintConfiguration => crate::install::print_configuration(),
         },
         #[cfg(feature = "install")]
         Opt::ExecInHostMountNamespace { args } => {

lib/src/install.rs

@@ -6,7 +6,7 @@
 
 // This sub-module is the "basic" installer that handles creating basic block device
 // and filesystem setup.
-mod baseline;
+pub(crate) mod baseline;
 
 use std::io::BufWriter;
 use std::io::Write;
@@ -429,6 +429,13 @@ impl SourceInfo {
     }
 }
 
+pub(crate) fn print_configuration() -> Result<()> {
+    let mut install_config = config::load_config()?;
+    install_config.filter_to_external();
+    let stdout = std::io::stdout().lock();
+    serde_json::to_writer(stdout, &install_config).map_err(Into::into)
+}
+
 pub(crate) mod config {
     use super::*;
 
@@ -447,6 +454,7 @@ pub(crate) mod config {
         /// Root filesystem type
         pub(crate) root_fs_type: Option<super::baseline::Filesystem>,
         /// Kernel arguments, applied at installation time
+        #[serde(skip_serializing_if = "Option::is_none")]
         pub(crate) kargs: Option<Vec<String>>,
     }
 
@@ -465,6 +473,11 @@ pub(crate) mod config {
                     .extend(other_kargs)
             }
         }
+
+        // Remove all configuration which is handled by `install to-filesystem`.
+        pub(crate) fn filter_to_external(&mut self) {
+            self.kargs.take();
+        }
     }
 
     #[context("Loading configuration")]

lib/src/privtests.rs

@@ -1,12 +1,13 @@
 use std::process::Command;
 
-use anyhow::Result;
+use anyhow::{Context, Result};
 use camino::Utf8Path;
 use fn_error_context::context;
 use rustix::fd::AsFd;
 use xshell::{cmd, Shell};
 
 use crate::blockdev::LoopbackDevice;
+use crate::install::config::InstallConfiguration;
 
 use super::cli::TestingOpts;
 use super::spec::Host;
@@ -98,6 +99,14 @@ pub(crate) fn impl_run_container() -> Result<()> {
     let stderr = String::from_utf8(o.stderr)?;
     assert!(stderr.contains("requires root privileges"));
 
+    let config = cmd!(sh, "bootc install print-configuration").read()?;
+    let config: InstallConfiguration =
+        serde_json::from_str(&config).context("Parsing install config")?;
+    assert_eq!(
+        config.root_fs_type.unwrap(),
+        crate::install::baseline::Filesystem::Xfs
+    );
+
     println!("ok container integration testing");
     Ok(())
 }