Use --pull-policy if-not-present when running pack build

.github/workflows/ci.yml

@@ -60,17 +60,12 @@ jobs:
         uses: Swatinem/rust-cache@v1.3.0
       - name: Install Pack CLI
         uses: buildpacks/github-actions/setup-pack@v4.6.0
-      - name: Configure Pack CLI
-        # Default to a small non-libc image for faster CI + to validate the static musl cross-compilation.
-        # Adjust pull-policy to prevent redundant image-pulling, which slows CI and risks hitting registry rate limits.
-        run: |
-          pack config default-builder cnbs/sample-builder:alpine
-          pack config pull-policy if-not-present
       - name: Run integration tests
         # Runs any tests annotated with the `#[ignore]` attribute (which in this repo, are all of the integration tests).
         run: cargo test -- --ignored
       - name: Compile and package examples/basics
         run: cargo run --package libcnb-cargo -- libcnb package
         working-directory: ./examples/basics
       - name: Pack build using examples/basics
-        run: pack build example-basics --buildpack target/buildpack/debug/libcnb-examples_basics --path examples/
+        # Uses a non-libc image to validate the static musl cross-compilation.
+        run: pack build example-basics --builder cnbs/sample-builder:alpine --buildpack target/buildpack/debug/libcnb-examples_basics --path examples/

libcnb-test/CHANGELOG.md

@@ -6,6 +6,7 @@
 - Replaced `IntegrationTestContext::start_container` with `IntegrationTestContext::prepare_container`, allowing users to configure the container before starting it. Ports can now be exposed via `PrepareContainerContext::expose_port`. ([#346](https://github.com/Malax/libcnb.rs/pull/346))
 - Added the ability to set environment variables for the container via `PrepareContainerContext::env` and `PrepareContainerContext::envs`. ([#346](https://github.com/Malax/libcnb.rs/pull/346))
 - Switch from `libcnb-cargo` to the new `libcnb-package` crate for buildpack packaging, which improves compile times due to it not including CLI-related dependencies ([#362](https://github.com/Malax/libcnb.rs/pull/362)).
+- Use `--pull-policy if-not-present` when running `pack build` ([#373](https://github.com/Malax/libcnb.rs/pull/373)).
 
 ## [0.2.0] 2022-02-28
 

libcnb-test/src/lib.rs

@@ -17,7 +17,7 @@ mod util;
 pub use crate::container_context::{
     ContainerContext, ContainerExecResult, PrepareContainerContext,
 };
-use crate::pack::PackBuildCommand;
+use crate::pack::{PackBuildCommand, PullPolicy};
 use bollard::image::RemoveImageOptions;
 use bollard::Docker;
 use std::collections::HashMap;
@@ -233,8 +233,13 @@ impl IntegrationTest {
 
         let image_name = util::random_docker_identifier();
 
-        let mut pack_command =
-            PackBuildCommand::new(&self.builder_name, temp_app_dir.path(), &image_name);
+        let mut pack_command = PackBuildCommand::new(
+            &self.builder_name,
+            temp_app_dir.path(),
+            &image_name,
+            // Prevent redundant image-pulling, which slows tests and risks hitting registry rate limits.
+            PullPolicy::IfNotPresent,
+        );
 
         self.env.iter().for_each(|(key, value)| {
             pack_command.env(key, value);

libcnb-test/src/pack.rs

@@ -7,10 +7,11 @@ use tempfile::TempDir;
 #[derive(Clone, Debug)]
 pub(crate) struct PackBuildCommand {
     builder: String,
-    path: PathBuf,
-    image_name: String,
     buildpacks: Vec<BuildpackReference>,
     env: BTreeMap<String, String>,
+    image_name: String,
+    path: PathBuf,
+    pull_policy: PullPolicy,
     verbose: bool,
 }
 
@@ -38,18 +39,32 @@ impl From<String> for BuildpackReference {
     }
 }
 
+#[derive(Clone, Debug)]
+/// Controls whether Pack should pull images.
+#[allow(dead_code)]
+pub(crate) enum PullPolicy {
+    /// Always pull images.
+    Always,
+    /// Use local images if they are already present, rather than pulling updated images.
+    IfNotPresent,
+    /// Never pull images. If the required images are not already available locally the pack command will fail.
+    Never,
+}
+
 impl PackBuildCommand {
     pub fn new(
         builder: impl Into<String>,
         path: impl Into<PathBuf>,
         image_name: impl Into<String>,
+        pull_policy: PullPolicy,
     ) -> PackBuildCommand {
         PackBuildCommand {
             builder: builder.into(),
-            path: path.into(),
-            image_name: image_name.into(),
-            buildpacks: vec![],
+            buildpacks: Vec::new(),
             env: BTreeMap::new(),
+            image_name: image_name.into(),
+            path: path.into(),
+            pull_policy,
             verbose: false,
         }
     }
@@ -76,6 +91,12 @@ impl From<PackBuildCommand> for Command {
             pack_build_command.builder,
             String::from("--path"),
             pack_build_command.path.to_string_lossy().to_string(),
+            String::from("--pull-policy"),
+            match pack_build_command.pull_policy {
+                PullPolicy::Always => "always".to_string(),
+                PullPolicy::IfNotPresent => "if-not-present".to_string(),
+                PullPolicy::Never => "never".to_string(),
+            },
         ];
 
         for buildpack in pack_build_command.buildpacks {
@@ -115,8 +136,6 @@ mod tests {
     fn from_pack_build_command_to_command() {
         let mut input = PackBuildCommand {
             builder: String::from("builder:20"),
-            path: PathBuf::from("/tmp/foo/bar"),
-            image_name: String::from("my-image"),
             buildpacks: vec![
                 BuildpackReference::Id(String::from("libcnb/buildpack1")),
                 BuildpackReference::Path(PathBuf::from("/tmp/buildpack2")),
@@ -125,6 +144,9 @@ mod tests {
                 (String::from("ENV_FOO"), String::from("FOO_VALUE")),
                 (String::from("ENV_BAR"), String::from("WHITESPACE VALUE")),
             ]),
+            image_name: String::from("my-image"),
+            path: PathBuf::from("/tmp/foo/bar"),
+            pull_policy: PullPolicy::IfNotPresent,
             verbose: true,
         };
 
@@ -141,6 +163,8 @@ mod tests {
                 "builder:20",
                 "--path",
                 "/tmp/foo/bar",
+                "--pull-policy",
+                "if-not-present",
                 "--buildpack",
                 "libcnb/buildpack1",
                 "--buildpack",