refactor: centralize all of the deb_import functionality in deb_impor…

…t.bzl

Refactor the package repo templates into their own methods and massively
cleanup the `for`-loop in `_deb_package_index_impl`.

IMHO overall now there's a much better and clear separation of concerns
between the "deb_translate_lock" repo and the "package repos"
(`apt/private/deb_import.bzl`).

apt/apt.bzl

@@ -114,8 +114,8 @@ def _apt_install(
                 and avoid the DEBUG messages.
         package_template: (EXPERIMENTAL!) a template file for generated BUILD
                           files. Available template replacement keys are:
-                          `{target_name}`, `{deps}`, `{urls}`, `{name}`,
-                          `{arch}`, `{sha256}`, `{repo_name}`
+                          `{target_name}`, `{src}`, `{deps}`, `{urls}`,
+                          `{name}`, `{arch}`, `{sha256}`, `{repo_name}`
         resolve_transitive: whether dependencies of dependencies should be
                             resolved and added to the lockfile.
     """

apt/private/BUILD.bazel

@@ -107,6 +107,7 @@ bzl_library(
     srcs = ["deb_import.bzl"],
     visibility = ["//apt:__subpackages__"],
     deps = [
+        ":starlark_codegen",
         ":util",
         "@bazel_tools//tools/build_defs/repo:http.bzl",
     ],

apt/private/deb_import.bzl

@@ -1,9 +1,9 @@
 "deb_import"
 
 load("@bazel_tools//tools/build_defs/repo:http.bzl", "http_archive")
+load(":starlark_codegen.bzl", "starlark")
 load(":util.bzl", "util")
 
-# BUILD.bazel template
 _DEB_IMPORT_BUILD_TMPL = '''
 genrule(
     name = "data",
@@ -62,8 +62,68 @@ def make_deb_import_key(repo_name, package):
         util.sanitize(package.version),
     )
 
-def deb_import(**kwargs):
+def deb_import(name, url, sha256, **kwargs):
     http_archive(
+        name = name,
+        url = url,
+        sha256 = sha256,
         build_file_content = _DEB_IMPORT_BUILD_TMPL,
         **kwargs
     )
+
+def _deb_import_tmpl(repo_name, package):
+    deb_import_key = make_deb_import_key(repo_name, package)
+
+    return '''\
+    deb_import(
+        name = "{name}",
+        url = "{url}",
+        sha256 = "{sha256}",
+    )
+'''.format(name = deb_import_key, url = package.url, sha256 = package.sha256)
+
+def deb_packages(repo_name, packages):
+    deb_imports = [
+        _deb_import_tmpl(repo_name, package)
+        for architectures in packages.values()
+        for package in architectures.values()
+    ]
+
+    return '''\
+"""Generated by rules_distroless. DO NOT EDIT."""
+load("@rules_distroless//apt/private:deb_import.bzl", "deb_import")
+
+# buildifier: disable=function-docstring
+def {repo_name}_packages():
+{deb_imports}
+'''.format(
+        repo_name = repo_name,
+        deb_imports = "\n".join(deb_imports) if deb_imports else "    pass",
+    )
+
+def package_build(package, repo_prefix, repo_name, template):
+    deb_import_key = make_deb_import_key(repo_name, package)
+
+    pkg_repo_name = "@%s%s" % (repo_prefix, deb_import_key)
+
+    alias_data = starlark.gen("%s//:data" % pkg_repo_name)
+    alias_control = starlark.gen("%s//:control" % pkg_repo_name)
+
+    deps = [
+        "//%s/%s" % (dep.name, package.arch)
+        for dep in package.dependencies
+    ]
+    deps = starlark.gen(deps, indent_count = 1)
+
+    return template.format(
+        target_name = package.arch,
+        src = '"@%s%s//:data"' % (repo_prefix, deb_import_key),
+        deps = deps,
+        urls = [package.url],
+        name = package.name,
+        arch = package.arch,
+        sha256 = package.sha256,
+        repo_name = pkg_repo_name,
+        alias_data = alias_data,
+        alias_control = alias_control,
+    )

apt/private/deb_translate_lock.bzl

@@ -1,26 +1,8 @@
 "repository rule for generating a dependency graph from a lockfile."
 
-load(":deb_import.bzl", "make_deb_import_key")
+load(":deb_import.bzl", "deb_packages", "package_build")
 load(":lockfile.bzl", "lockfile")
 
-# header template for packages.bzl file
-_DEB_IMPORT_HEADER_TMPL = '''\
-"""Generated by rules_distroless. DO NOT EDIT."""
-load("@rules_distroless//apt/private:deb_import.bzl", "deb_import")
-
-# buildifier: disable=function-docstring
-def {}_packages():
-'''
-
-# deb_import template for packages.bzl file
-_DEB_IMPORT_TMPL = '''\
-    deb_import(
-        name = "{name}",
-        urls = {urls},
-        sha256 = "{sha256}",
-    )
-'''
-
 _BUILD_TMPL = """\
 exports_files(glob(['packages.bzl']))
 
@@ -31,51 +13,32 @@ alias(
 """
 
 def _deb_translate_lock_impl(rctx):
-    lock_content = rctx.attr.lock_content
-    package_template = rctx.read(rctx.attr.package_template)
-    lockf = lockfile.from_json(rctx, lock_content if lock_content else rctx.read(rctx.attr.lock))
-
-    package_defs = []
-
-    if not lock_content:
-        package_defs = [_DEB_IMPORT_HEADER_TMPL.format(rctx.attr.name)]
+    lockf = lockfile.from_json(
+        rctx,
+        rctx.attr.lock_content or rctx.read(rctx.attr.lock),
+    )
+    lockf.write("lock.json")
 
-        if not lockf.packages:
-            package_defs.append("   pass")
+    repo_prefix = "@" if rctx.attr.lock_content else ""
+    repo_name = rctx.attr.name
 
     for package in lockf.packages():
-        deb_import_key = make_deb_import_key(rctx.attr.name, package)
-
-        if not lock_content:
-            package_defs.append(
-                _DEB_IMPORT_TMPL.format(
-                    name = deb_import_key,
-                    package_name = package.name,
-                    urls = [package.url],
-                    sha256 = package.sha256,
-                ),
-            )
-
-        repo_name = "%s%s" % ("@" if lock_content else "", deb_import_key)
-
         rctx.file(
             "%s/%s/BUILD.bazel" % (package.name, package.arch),
-            package_template.format(
-                target_name = package.arch,
-                src = '"@%s//:data"' % repo_name,
-                deps = ",\n        ".join([
-                    '"//%s/%s"' % (dep.name, package.arch)
-                    for dep in package.dependencies
-                ]),
-                urls = [package.url],
-                name = package.name,
-                arch = package.arch,
-                sha256 = package.sha256,
-                repo_name = "%s" % repo_name,
+            package_build(
+                package,
+                repo_prefix,
+                repo_name,
+                rctx.read(rctx.attr.package_template),
             ),
         )
 
-    rctx.file("packages.bzl", "\n".join(package_defs))
+    if rctx.attr.lock_content:
+        packages_bzl = ""
+    else:
+        packages_bzl = deb_packages(repo_name, lockf.packages)
+
+    rctx.file("packages.bzl", packages_bzl)
     rctx.file("BUILD.bazel", _BUILD_TMPL.format(rctx.attr.name.split("~")[-1]))
 
 deb_translate_lock = repository_rule(

apt/private/package.BUILD.tmpl

@@ -1,19 +1,28 @@
+"""Generated by rules_distroless. DO NOT EDIT."""
+
 alias(
     name = "data",
-    actual = "@{repo_name}//:data",
+    actual = {alias_data},
     visibility = ["//visibility:public"],
 )
 
 alias(
     name = "control",
-    actual = "@{repo_name}//:control",
+    actual = {alias_control},
     visibility = ["//visibility:public"],
 )
 
 filegroup(
-    name = "{target_name}",
+    name = "deps",
+    srcs = {deps},
     visibility = ["//visibility:public"],
+)
+
+filegroup(
+    name = "{target_name}",
     srcs = [
-        {deps}
-    ] + [":data"]
-)
+        ":deps",
+        ":data",
+    ],
+    visibility = ["//visibility:public"],
+)