feat: allow build to export artifacts

Sponsored-by: author

4 files changed, 56 insertions, 3 deletions

diff --git a/ambient-run.md b/ambient-run.md
index 1690cce..d143acb 100644
--- a/ambient-run.md
+++ b/ambient-run.md
@@ -165,6 +165,7 @@ source: .
 shell: |
   cargo test
 image: /my/image.qcow2
+artifact: null
 ~~~
 
 ### Show per-build configuration
@@ -226,6 +227,36 @@ shell: |
 image: image.qcow2
 ~~~
 
+### Build produces an artifact
+
+_Requirement:_ The build can produce an artifact.
+
+_Justification:_ Without this a build can't produce something that can
+be used after the build has finished.
+
+_Stakeholder:_ Lars.
+
+~~~scenario
+given an installed ambient-run
+given file artifact-project.yaml
+given file foo/README.md from foo-project.yaml
+given image file image.qcow2 specified for test suite
+when I run ambient-run build artifact-project.yaml --log foo.log
+then file foo.tar exists
+when I run tar tf foo.tar
+then stdout contains "README.md"
+~~~
+
+
+~~~{#artifact-project.yaml .file .yaml}
+source: foo
+shell: |
+  #!/bin/bash
+  tar -cf /dev/vdc .
+image: image.qcow2
+artifact: foo.tar
+~~~
+
 ### Build is given dependencies
 ### Cache is persistent between builds
 ### Build gets the resources is demands
diff --git a/src/bin/ambient-run.rs b/src/bin/ambient-run.rs
index e1f1b16..3dc778e 100644
--- a/src/bin/ambient-run.rs
+++ b/src/bin/ambient-run.rs
@@ -215,7 +215,8 @@ impl BuildCommand {
         let project = Project::load(&self.filename, config)?;
         let mut qemu = Qemu::new(&project.image())
             .with_shell(project.shell())
-            .with_source(&project.source());
+            .with_source(&project.source())
+            .with_artifact(project.artifact());
         if let Some(log) = &self.log {
             qemu = qemu.with_log(log);
         }
diff --git a/src/project.rs b/src/project.rs
index 8a182bc..b381734 100644
--- a/src/project.rs
+++ b/src/project.rs
@@ -12,6 +12,7 @@ pub struct Project {
     source: PathBuf,
     shell: String,
     image: PathBuf,
+    artifact: Option<PathBuf>,
 }
 
 impl Project {
@@ -43,6 +44,7 @@ impl Project {
             source: PathBuf::from("."),
             shell: "".into(),
             image,
+            artifact: None,
         };
         project.add_from(filename)?;
         if project.shell.is_empty() {
@@ -68,6 +70,7 @@ impl Project {
         if let Some(x) = snippet.image {
             self.image = x;
         }
+        self.artifact = snippet.artifact;
         Ok(())
     }
 
@@ -90,6 +93,11 @@ impl Project {
     pub fn shell(&self) -> &str {
         self.shell.as_ref()
     }
+
+    /// Artifact file.
+    pub fn artifact(&self) -> &Option<PathBuf> {
+        &self.artifact
+    }
 }
 
 #[derive(Debug, Deserialize)]
@@ -98,6 +106,7 @@ struct ProjectSnippet {
     source: Option<PathBuf>,
     shell: Option<String>,
     image: Option<PathBuf>,
+    artifact: Option<PathBuf>,
 }
 
 /// Possible errors from configuration file handling.
diff --git a/src/qemu.rs b/src/qemu.rs
index c48213f..3450101 100644
--- a/src/qemu.rs
+++ b/src/qemu.rs
@@ -18,6 +18,7 @@ pub struct Qemu {
     log: Option<PathBuf>,
     source: PathBuf,
     shell: Option<String>,
+    artifact: Option<PathBuf>,
 }
 
 impl Qemu {
@@ -48,6 +49,12 @@ impl Qemu {
         self
     }
 
+    /// Set output artifact filename.
+    pub fn with_artifact(mut self, artifact: &Option<PathBuf>) -> Self {
+        self.artifact = artifact.clone();
+        self
+    }
+
     /// Run QEMU in the specified way.
     pub fn run(&self) -> Result<(), QemuError> {
         eprintln!("qemu run");
@@ -62,8 +69,13 @@ impl Qemu {
         copy(OVMF_FD, &vars).map_err(|e| QemuError::Copy(OVMF_FD.into(), e))?;
 
         eprintln!("output drive");
-        let output_drive =
-            Self::create_tar_with_size(tmp.path().join("output"), empty.path(), MAX_OUTPUT_SIZE)?;
+        let output_drive = if let Some(filename) = &self.artifact {
+            eprintln!("output to {}", filename.display());
+            Self::create_tar_with_size(filename.to_path_buf(), empty.path(), MAX_OUTPUT_SIZE)?
+        } else {
+            eprintln!("empty output drive");
+            Self::create_tar_with_size(tmp.path().join("output"), empty.path(), 0)?
+        };
 
         eprintln!("cache drive");
         let cache_drive =