Convert make-amis to python

This is paving the way for identity broker improvements for opt-in
regions. Eventually we'll need to hook some region logic into these
scripts so having them written in python will be helpful.

Makefile

@@ -24,9 +24,9 @@ __check_defined = \
 
 .PHONY: amis prune release-readme clean
 
-amis: build build/packer.json build/profile/$(PROFILE) build/update-release.py
+amis: build build/packer.json build/profile/$(PROFILE) build/update-release.py build/make-amis.py
 	@:$(call check_defined, PROFILE, target profile name)
-	build/make-amis $(PROFILE) $(BUILDS)
+	build/make-amis.py $(PROFILE) $(BUILDS)
 
 prune: build build/prune-amis.py
 	@:$(call check_defined, LEVEL, pruning level)

scripts/make-amis

@@ -1,39 +0,0 @@
-#!/bin/sh
-# vim: set ts=4 et:
-
-export PACKER=${PACKER:-packer}
-
-cd build || exit 1
-
-# we need a profile, at least
-if [ $# -eq 0 ]; then
-    echo "Usage: $(basename "$0") <profile> [ <build> ... ]" >&2
-    exit 1
-fi
-
-PROFILE=$1; shift
-
-# no build(s) specified?  do all the builds!
-[ $# -gt 0 ] && BUILDS="$*" || BUILDS=$(ls "profile/$PROFILE")
-
-for BUILD in $BUILDS
-do
-    printf "\n*** Building %s/%s ***\n\n" "$PROFILE" "$BUILD"
-    BUILD_DIR="profile/$PROFILE/$BUILD"
-
-    # execute packer, capture output and exit code
-    (
-        "$PACKER" build -var-file="$BUILD_DIR/vars.json" packer.json
-        echo $? >"$BUILD_DIR/exit"
-    ) | tee "$BUILD_DIR/output"
-    EXIT=$(cat "$BUILD_DIR/exit")
-
-    if [ "$EXIT" -eq 0 ]; then
-        ./update-release.py "$PROFILE" "$BUILD"
-    else
-        # unless AMI revision already exists, exit
-        grep -q 'is used by an existing AMI' "$BUILD_DIR/output" || exit "$EXIT"
-    fi
-done
-
-echo "\n=== DONE ===\n"

scripts/make-amis.py.in

@@ -0,0 +1,68 @@
+@PYTHON@
+# vim: set ts=4 et:
+
+import os
+import io
+import sys
+import argparse
+import subprocess
+
+
+def find_repo_root():
+    path = os.getcwd()
+
+    while ".git" not in set(os.listdir(path)) and path != "/":
+        path = os.path.dirname(path)
+
+    if path == "/":
+        raise Exception("No repo found, stopping at /")
+
+    return path
+
+
+def main(args):
+    parser = argparse.ArgumentParser(description="Build Packer JSON variable "
+        "files from HOCON build profiles")
+    parser.add_argument("profile", help="name of profile to build")
+    parser.add_argument("builds", nargs="*",
+        help="name of builds within a profile to build")
+    args = parser.parse_args()
+
+    os.chdir(os.path.join(find_repo_root(), "build"))
+
+    builds = args.builds or os.listdir(os.path.join("profile", args.profile))
+    for build in builds:
+        print(f"\n*** Building {args.profile}/{build} ***\n\n")
+
+        build_dir = os.path.join("profile", args.profile, build)
+        if not os.path.exists(build_dir):
+            print(f"Build dir '{build_dir}' does not exist")
+            break
+
+        out = io.StringIO()
+
+        res = subprocess.Popen([
+                os.environ.get("PACKER", "packer"),
+                "build",
+                f"-var-file={build_dir}/vars.json",
+                "packer.json"
+            ], stdout=subprocess.PIPE, encoding="utf-8")
+
+        while res.poll() is None:
+            text = res.stdout.readline()
+            out.write(text)
+            print(text, end="")
+
+        if res.returncode == 0:
+            subprocess.run(["./update-release.py", args.profile, build])
+        else:
+            if "is used by an existing AMI" in out.getvalue():
+                continue
+            else:
+                sys.exit(res.returncode)
+
+    print("\n=== DONE ===\n")
+
+
+if __name__ == "__main__":
+    main(sys.argv)