Add support for snaps (Azure#582)

This change updates the repo to support building IoT Identity Service components as snaps. One of the main differences with snaps is that they run in a tightly confined sandbox, so many hard-coded references to users and filesystem paths had to be adapted to support compile-time variables.

.github/workflows/packages.yaml

@@ -92,3 +92,38 @@ jobs:
       with:
         name: "${{ steps.generate-artifact-properties.outputs.artifact-name }}"
         path: 'packages'
+
+  snap:
+    strategy:
+      fail-fast: false
+
+      matrix:
+        runner:
+        - arch: amd64
+          pool: iot-identity-1es-hosted-linux-amd64
+          image: agent-aziotedge-ubuntu-22.04-msmoby
+        - arch: aarch64
+          pool: iot-identity-1es-hosted-linux-arm64
+          image: agent-aziotedge-ubuntu-22.04-arm64-msmoby
+
+    runs-on:
+    - self-hosted
+    - 1ES.Pool=${{ matrix.runner.pool }}
+    - 1ES.ImageOverride=${{ matrix.runner.image }}
+
+    steps:
+    - uses: 'actions/checkout@v3'
+      with:
+        submodules: 'recursive'
+
+    - name: 'Run'
+      uses: 'snapcore/action-build@v1'
+      id: 'snapcraft'
+      with:
+        build-info: true
+
+    - name: 'Upload'
+      uses: 'actions/upload-artifact@v3'
+      with:
+        name: 'packages_snap_${{ matrix.runner.arch }}'
+        path: '${{ steps.snapcraft.outputs.snap }}'

.gitignore

@@ -2,3 +2,8 @@
 /packages
 /target
 .vscode
+
+/parts
+/stage
+/prime
+*.snap

Makefile

@@ -2,6 +2,15 @@
 BINDGEN = bindgen
 CBINDGEN = cbindgen
 
+# Default users under which the services will run. Override by specifying on the CLI for make.
+USER_AZIOTID ?= aziotid
+USER_AZIOTCS ?= aziotcs
+USER_AZIOTKS ?= aziotks
+USER_AZIOTTPM ?= aziottpm
+
+# Default socket directory. Override by specifying on the CLI for make.
+SOCKET_DIR ?= /run/aziot
+
 # 0 => false, _ => true
 V = 0
 
@@ -20,6 +29,15 @@ ARCH =
 
 INSTALL_PRESET = true
 
+# Enable special features for specific runtime platforms
+# '' => none, 'snapd' => snapd features
+PLATFORM_FEATURES ?=
+CARGO_FEATURES =
+
+ifeq ($(PLATFORM_FEATURES), snapd)
+	CARGO_FEATURES += --features snapctl
+endif
+
 ifeq ($(V), 0)
 	BINDGEN_VERBOSE =
 	CARGO_VERBOSE = --quiet
@@ -38,11 +56,11 @@ else
 	CARGO_PROFILE_DIRECTORY = release
 endif
 
-ifeq ($(ARCH), arm32v7)
+ifneq (,$(filter $(ARCH), arm32v7 armhf))
 	CARGO_TARGET = armv7-unknown-linux-gnueabihf
     CROSS_HOST_TRIPLE = arm-linux-gnueabihf
 	DPKG_ARCH_FLAGS = --host-arch armhf
-else ifeq ($(ARCH), aarch64)
+else ifneq (,$(filter $(ARCH), aarch64 arm64))
 	CARGO_TARGET = aarch64-unknown-linux-gnu
     CROSS_HOST_TRIPLE = aarch64-linux-gnu
 	DPKG_ARCH_FLAGS = --host-arch arm64 --host-type aarch64-linux-gnu --target-type aarch64-linux-gnu
@@ -56,7 +74,12 @@ CARGO_OUTPUT_ABSPATH = $(abspath ./target/$(CARGO_TARGET)/$(CARGO_PROFILE_DIRECT
 VENDOR_PREFIX = $(CARGO_OUTPUT_ABSPATH)/fakeroot
 VENDOR_PKGCONFIG = $(VENDOR_PREFIX)$(AZIOT_PRIVATE_LIBRARIES)/pkgconfig
 
-CARGO = VENDOR_PREFIX="$(VENDOR_PREFIX)" VENDOR_PKGCONFIG="$(VENDOR_PKGCONFIG)" cargo
+CARGO = VENDOR_PREFIX="$(VENDOR_PREFIX)" VENDOR_PKGCONFIG="$(VENDOR_PKGCONFIG)" \
+		USER_AZIOTID="$(USER_AZIOTID)" \
+		USER_AZIOTCS="$(USER_AZIOTCS)" \
+		USER_AZIOTKS="$(USER_AZIOTKS)" \
+		USER_AZIOTTPM="$(USER_AZIOTTPM)" \
+		SOCKET_DIR="$(SOCKET_DIR)" cargo
 
 # Some of the targets use bash-isms like `set -o pipefail`
 SHELL = /bin/bash
@@ -96,7 +119,7 @@ default:
 	# incorrect assumption of /usr/local.  There is probably a better
 	# way to do this...
 	set -euo pipefail; \
-	if [ -d third-party/tpm2-tss ]; then \
+	if [ $(VENDOR_LIBTSS) != 0 -a -d third-party/tpm2-tss ]; then \
 		cd third-party/tpm2-tss; \
 		./bootstrap; \
 		./configure \
@@ -120,13 +143,13 @@ default:
 	# See the doc header of the aziot-keys-common crate for more info.
 	$(CARGO) build \
 		-p aziot-keys \
-		$(CARGO_PROFILE) --target $(CARGO_TARGET) $(CARGO_VERBOSE)
+		$(CARGO_PROFILE) $(CARGO_FEATURES) --target $(CARGO_TARGET) $(CARGO_VERBOSE)
 
 	$(CARGO) build \
 		-p aziotctl \
 		-p aziotd \
 		-p aziot-key-openssl-engine-shared \
-		$(CARGO_PROFILE) --target $(CARGO_TARGET) $(CARGO_VERBOSE)
+		$(CARGO_PROFILE) $(CARGO_FEATURES) --target $(CARGO_TARGET) $(CARGO_VERBOSE)
 
 clean:
 	$(CARGO) clean $(CARGO_VERBOSE)
@@ -309,6 +332,9 @@ deb: dist
 	# Copy package files
 	cp -R contrib/debian /tmp/aziot-identity-service-$(PACKAGE_VERSION)/
 	sed -i -e 's/@version@/$(PACKAGE_VERSION)/g; s/@release@/$(PACKAGE_RELEASE)/g' /tmp/aziot-identity-service-$(PACKAGE_VERSION)/debian/changelog
+	sed -i -e 's/@user_aziotid@/$(USER_AZIOTID)/g; s/@user_aziotks@/$(USER_AZIOTKS)/g; s/@user_aziotcs@/$(USER_AZIOTCS)/g; s/@user_aziottpm@/$(USER_AZIOTTPM)/g' /tmp/aziot-identity-service-$(PACKAGE_VERSION)/debian/postinst
+	sed -i -e 's/@user_aziotid@/$(USER_AZIOTID)/g; s/@user_aziotks@/$(USER_AZIOTKS)/g; s/@user_aziotcs@/$(USER_AZIOTCS)/g; s/@user_aziottpm@/$(USER_AZIOTTPM)/g; s|@socket_dir@|$(SOCKET_DIR)|g' /tmp/aziot-identity-service-$(PACKAGE_VERSION)/debian/postrm
+	sed -i -e 's/@user_aziotid@/$(USER_AZIOTID)/g; s/@user_aziotks@/$(USER_AZIOTKS)/g; s/@user_aziotcs@/$(USER_AZIOTCS)/g; s/@user_aziottpm@/$(USER_AZIOTTPM)/g' /tmp/aziot-identity-service-$(PACKAGE_VERSION)/debian/preinst
 
 	cd /tmp/aziot-identity-service-$(PACKAGE_VERSION) && dpkg-buildpackage -us -uc $(DPKG_ARCH_FLAGS)
 
@@ -359,6 +385,10 @@ rpm:
 		-e "s|@devtoolset@|$$DEVTOOLSET|g" \
 		-e "s|@llvm_toolset@|$$LLVM_TOOLSET|g" \
 		-e "s|@openssl_engine_filename@|$$OPENSSL_ENGINE_FILENAME|g" \
+		-e "s/@user_aziotid@/$(USER_AZIOTID)/g" \
+		-e "s/@user_aziotks@/$(USER_AZIOTKS)/g" \
+		-e "s/@user_aziotcs@/$(USER_AZIOTCS)/g" \
+		-e "s/@user_aziottpm@/$(USER_AZIOTTPM)/g" \
 		>$(RPMBUILDDIR)/SPECS/aziot-identity-service.spec
 
 	# Copy preset file to be included in the package
@@ -427,7 +457,7 @@ install-common:
 	# tpm2-tss
 	# See comment above regarding environment bleedover on RPM
 	# builds.
-	if [ -d third-party/tpm2-tss ]; then \
+	if [ $(VENDOR_LIBTSS) != 0 -a -d third-party/tpm2-tss ]; then \
 		cd third-party/tpm2-tss; \
 		$(MAKE) libdir=$(AZIOT_PRIVATE_LIBRARIES) install-exec; \
 	fi
@@ -457,15 +487,28 @@ install-common:
 	$(INSTALL) -d -m 0700 $(DESTDIR)$(localstatedir)/lib/aziot/tpmd
 
 	# Systemd services and sockets
+	$(INSTALL) -d $(DESTDIR)$(unitdir)
 	# NOTE: We do not use "install -D ... -t ..." since it is broken on
 	# RHEL 7 derivatives and will not be fixed.
 	# Ref: https://bugzilla.redhat.com/show_bug.cgi?format=multiple&id=1758488
 	for i in cert identity key tpm; do \
+		OUTPUT_SOCKET="$(DESTDIR)$(unitdir)/aziot-$${i}d.socket"; \
+		<"$$i/aziot-$${i}d/aziot-$${i}d.socket.in" sed \
+			-e 's|@user_aziotid@|$(USER_AZIOTID)|' \
+			-e 's|@user_aziotks@|$(USER_AZIOTKS)|' \
+			-e 's|@user_aziotcs@|$(USER_AZIOTCS)|' \
+			-e 's|@user_aziottpm@|$(USER_AZIOTTPM)|' \
+			-e 's|@socket_dir@|$(SOCKET_DIR)|' \
+			>"$$OUTPUT_SOCKET"; \
+		chmod 0644 "$$OUTPUT_SOCKET"; \
 		OUTPUT_SERVICE="$(DESTDIR)$(unitdir)/aziot-$${i}d.service"; \
-		$(INSTALL_DATA) -D "$$i/aziot-$${i}d/aziot-$${i}d.socket" "$(DESTDIR)$(unitdir)/aziot-$${i}d.socket"; \
 		<"$$i/aziot-$${i}d/aziot-$${i}d.service.in" sed \
 			-e 's|@private-libs@|$(AZIOT_PRIVATE_LIBRARIES)|' \
 			-e 's|@libexecdir@|$(libexecdir)|' \
+			-e 's|@user_aziotid@|$(USER_AZIOTID)|' \
+			-e 's|@user_aziotks@|$(USER_AZIOTKS)|' \
+			-e 's|@user_aziotcs@|$(USER_AZIOTCS)|' \
+			-e 's|@user_aziottpm@|$(USER_AZIOTTPM)|' \
 			>"$$OUTPUT_SERVICE"; \
 		chmod 0644 "$$OUTPUT_SERVICE"; \
 	done

aziotctl/.cargo/config.toml

@@ -0,0 +1,6 @@
+[env]
+USER_AZIOTID = "aziotid"
+USER_AZIOTKS = "aziotks"
+USER_AZIOTCS = "aziotcs"
+USER_AZIOTTPM = "aziottpm"
+SOCKET_DIR = "/run/aziot"

aziotctl/Cargo.toml

@@ -53,3 +53,6 @@ openssl-sys2 = { path = "../openssl-sys2" }
 
 [dev-dependencies]
 bytes = "1"
+
+[features]
+snapctl = ["aziotctl-common/snapctl"]

aziotctl/aziotctl-common/Cargo.toml

@@ -26,3 +26,6 @@ http-common = { path = "../../http-common" }
 [dev-dependencies]
 bytes = "1"
 toml = "0.7"
+
+[features]
+snapctl = []

aziotctl/aziotctl-common/src/config/mod.rs

@@ -62,12 +62,22 @@ pub fn write_file(
     let path = path.as_ref();
     let path_displayable = path.display();
 
-    let () = fs::write(path, content)
-        .with_context(|| format!("could not create {}", path_displayable))?;
-    let () = unistd::chown(path, Some(user.uid), Some(user.gid))
-        .with_context(|| format!("could not set ownership on {}", path_displayable))?;
+    // We're about to truncate the file anyway, but it is a little safer to
+    // fully remove it, as a truncating write does not actually reset ownership
+    // or user permissions (which can lead to needing CAP_FOWNER, as then we
+    // encounter a set_permissions call on a file we may or may not own). We
+    // can just ignore any errors returned here as they either mean a) the file
+    // doesn't exist, in which case great, or b) there is some sort of permission
+    // or path error which will just crop up in the fs::write call anyway
+
+    let _file = fs::remove_file(path);
+
+    let () =
+        fs::write(path, content).with_context(|| format!("could not create {}", path_displayable))?;
     let () = fs::set_permissions(path, fs::Permissions::from_mode(mode))
         .with_context(|| format!("could not set permissions on {}", path_displayable))?;
+    let () = unistd::chown(path, Some(user.uid), Some(user.gid))
+        .with_context(|| format!("could not set ownership on {}", path_displayable))?;
 
     Ok(())
 }

aziotctl/aziotctl-common/src/lib.rs

@@ -139,10 +139,12 @@ pub fn is_rfc_1035_valid(hostname: &str) -> bool {
 }
 
 fn program_name() -> String {
-    std::env::args_os()
-        .next()
-        .and_then(|arg| arg.into_string().ok())
-        .unwrap_or_else(|| "<current program>".to_owned())
+    std::env::current_exe()
+        .expect("Cannot get the exec path")
+        .file_name()
+        .and_then(std::ffi::OsStr::to_str)
+        .unwrap_or("<current program>")
+        .to_owned()
 }
 
 #[cfg(test)]

aziotctl/aziotctl-common/src/system/mod.rs

@@ -18,6 +18,7 @@ pub struct ServiceDefinition {
 }
 
 // Note, the ordering is important, since the first service is considered the root and will be started by the restart command.
+#[cfg(not(feature = "snapctl"))]
 pub const SERVICE_DEFINITIONS: &[&ServiceDefinition] = &[
     &ServiceDefinition {
         service: "aziot-identityd.service",
@@ -37,6 +38,28 @@ pub const SERVICE_DEFINITIONS: &[&ServiceDefinition] = &[
     },
 ];
 
+// Ordering is not important here, we defer it to snapd
+#[cfg(feature = "snapctl")]
+pub const SERVICE_DEFINITIONS: &[&ServiceDefinition] = &[
+    &ServiceDefinition {
+        service: "snap.azure-iot-identity.identityd.service",
+        sockets: &["aziot-identityd.socket"],
+    },
+    &ServiceDefinition {
+        service: "snap.azure-iot-identity.keyd.service",
+        sockets: &["aziot-keyd.socket"],
+    },
+    &ServiceDefinition {
+        service: "snap.azure-iot-identity.certd.service",
+        sockets: &["aziot-certd.socket"],
+    },
+    &ServiceDefinition {
+        service: "snap.azure-iot-identity.tpmd.service",
+        sockets: &["aziot-tpmd.socket"],
+    },
+];
+
+#[cfg(not(feature = "snapctl"))]
 fn print_command_error(result: &std::process::Output) {
     use std::io::{self, Write};
 
@@ -49,3 +72,17 @@ fn print_command_error(result: &std::process::Output) {
     io::stdout().write_all(&result.stderr).unwrap();
     eprintln!();
 }
+
+#[cfg(feature = "snapctl")]
+fn print_command_error(result: &std::process::Output) {
+    use std::io::{self, Write};
+
+    eprintln!("snapctl exited with non-zero status code.");
+    eprintln!("stdout:");
+    eprintln!("=======");
+    io::stdout().write_all(&result.stdout).unwrap();
+    eprintln!("stderr:");
+    eprintln!("=======");
+    io::stdout().write_all(&result.stderr).unwrap();
+    eprintln!();
+}

aziotctl/aziotctl-common/src/system/restart.rs

@@ -6,6 +6,7 @@ use anyhow::{Context, Result};
 
 use super::{print_command_error, stop, ServiceDefinition};
 
+#[cfg(not(feature = "snapctl"))]
 pub fn restart(services: &[&ServiceDefinition]) -> Result<()> {
     // stop all services
     stop(services)?;
@@ -20,6 +21,7 @@ pub fn restart(services: &[&ServiceDefinition]) -> Result<()> {
     start(services[0].service)
 }
 
+#[cfg(not(feature = "snapctl"))]
 fn start(name: &str) -> Result<()> {
     print!("Starting {}...", name);
     let result = Command::new("systemctl")
@@ -35,3 +37,44 @@ fn start(name: &str) -> Result<()> {
 
     Ok(())
 }
+
+#[cfg(feature = "snapctl")]
+pub fn restart(services: &[&ServiceDefinition]) -> Result<()> {
+    // stop all services
+    stop(services)?;
+
+    // start all services
+    start(services)
+}
+
+#[cfg(feature = "snapctl")]
+pub fn start(services: &[&ServiceDefinition]) -> Result<()> {
+    let snap_instance_name = match std::env::var("SNAP_INSTANCE_NAME") {
+        Ok(snap_instance_name) => snap_instance_name,
+        Err(_) => {
+            std::env::var("SNAP_NAME").expect("snapctl must be used within the context of a snap")
+        }
+    };
+
+    print!("Starting {} services...", snap_instance_name);
+
+    let service_names = services.iter().map(|s| {
+        s.service
+            .trim_start_matches("snap.")
+            .trim_end_matches(".service")
+    });
+
+    let result = Command::new("snapctl")
+        .arg("start")
+        .args(service_names)
+        .output()
+        .context("Failed to call snapctl start")?;
+
+    if result.status.success() {
+        println!("Started!");
+    } else {
+        print_command_error(&result);
+    }
+
+    Ok(())
+}