software/ors-amarisoft: slapos-render-config: Remove duplicated code from slapos.recipe.template

For its operation slapos-render-config mimics jinja2 templates rendering
done for real in slapos. But to do so it currently duplicates the code
from slapos.recipe.template.

We can do the same by reusing slapos.recipe.template instead of
duplicating code from there.

-> Do it.

The output of generated gnb.cfg is the same before and after this patch.

/cc @xavier_thompson, @Daetalus
/reviewed-by @jhuge, @lu.xu, @tomo
/reviewed-on nexedi/slapos!1462

software/ors-amarisoft/slapos-render-config.py

@@ -3,6 +3,37 @@
 # It mimics the way config files are generated during the build but runs much
 # faster compared to full `slapos node software` + `slapos node instance` runs.
 
+import zc.buildout.buildout # XXX workaround for https://lab.nexedi.com/nexedi/slapos.recipe.template/merge_requests/9
+from slapos.recipe.template import jinja2_template
+
+import json
+
+
+# j2render renders config/<cfg>.jinja2.cfg into config/<cfg>.cfg with provided json parameters.
+def j2render(cfg, jcfg):
+    ctx = json.loads(jcfg)
+    textctx = ''
+    for k, v in ctx.items():
+        textctx += 'json %s %s\n' % (k, json.dumps(v))
+    buildout = None # stub
+    r = jinja2_template.Recipe(buildout, "recipe", {
+      'extensions': 'jinja2.ext.do',
+      'url': 'config/{}.jinja2.cfg'.format(cfg),
+      'output': 'config/{}.cfg'.format(cfg),
+      'context': textctx,
+      })
+    #print(r.context)
+
+    # avoid dependency on zc.buildout.download and the need to use non-stub buildout section
+    def _read(url, *args):
+        with open(url, *args) as f:
+            return f.read()
+    r._read = _read
+
+    with open('config/{}.cfg'.format(cfg), 'w+') as f:
+      f.write(r._render().decode())
+
+
 config = "gnb"
 json_params_empty = """{
     "rf_mode": 'fdd',
@@ -52,190 +83,5 @@ json_params = """{
         "tdd_ul_dl_config": "5ms 8UL 1DL 2/10 (maximum uplink)"
     }
 }"""
-import os
-import json
-from jinja2 import Environment, StrictUndefined, \
-    BaseLoader, TemplateNotFound, PrefixLoader
-import six
-
-DEFAULT_CONTEXT = {x.__name__: x for x in (
-    abs, all, any, bin, bool, bytes, callable, chr, complex, dict, divmod,
-    enumerate, filter, float, format, frozenset, hex, int,
-    isinstance, iter, len, list, map, max, min, next, oct, ord, pow,
-    range, repr, reversed, round, set, six, sorted, str, sum, tuple, zip)}
-
-if six.PY2:
-    import itertools
-    DEFAULT_CONTEXT.update(
-        filter=itertools.ifilter,
-        map=itertools.imap,
-        range=xrange,
-        zip=itertools.izip,
-    )
-
-def _assert(x, *args):
-    if x:
-        return ""
-    raise AssertionError(*args)
-DEFAULT_CONTEXT['assert'] = _assert
-
-DUMPS_KEY = 'dumps'
-DEFAULT_IMPORT_DELIMITER = '/'
-
-def getKey(expression, buildout, _, options):
-    section, entry = expression.split(':')
-    if section:
-        return buildout[section][entry]
-    else:
-        return options[entry]
-
-def getJsonKey(expression, buildout, _, __):
-    return json.loads(getKey(expression, buildout, _, __))
 
-EXPRESSION_HANDLER = {
-    'raw': (lambda expression, _, __, ___: expression),
-    'key': getKey,
-    'json': (lambda expression, _, __, ___: json.loads(expression)),
-    'jsonkey': getJsonKey,
-    'import': (lambda expression, _, __, ___:
-        __import__(expression, fromlist=['*'], level=0)),
-    'section': (lambda expression, buildout, _, __: dict(
-        buildout[expression])),
-}
-
-class RelaxedPrefixLoader(PrefixLoader):
-    """
-    Same as PrefixLoader, but accepts imports lacking separator.
-    """
-    def get_loader(self, template):
-        if self.delimiter not in template:
-            template += self.delimiter
-        return super(RelaxedPrefixLoader, self).get_loader(template)
-
-class RecipeBaseLoader(BaseLoader):
-    """
-    Base class for import classes altering import path.
-    """
-    def __init__(self, path, delimiter, encoding):
-        self.base = os.path.normpath(path)
-        self.delimiter = delimiter
-        self.encoding = encoding
-
-    def get_source(self, environment, template):
-        path = self._getPath(template)
-        # Code adapted from jinja2's doc on BaseLoader.
-        if path is None or not os.path.exists(path):
-            raise TemplateNotFound(template)
-        mtime = os.path.getmtime(path)
-        with open(path, 'rb') as f:
-            source = f.read().decode(self.encoding)
-        return source, path, lambda: mtime == os.path.getmtime(path)
-
-    def _getPath(self, template):
-        raise NotImplementedError
-
-class FileLoader(RecipeBaseLoader):
-    """
-    Single-path loader.
-    """
-    def _getPath(self, template):
-        if template:
-            return None
-        return self.base
-
-class FolderLoader(RecipeBaseLoader):
-    """
-    Multi-path loader (to allow importing a folder's content).
-    """
-    def _getPath(self, template):
-        path = os.path.normpath(os.path.join(
-            self.base,
-            *template.split(self.delimiter)
-        ))
-        if path.startswith(self.base):
-            return path
-        return None
-
-LOADER_TYPE_DICT = {
-    'rawfile': (FileLoader, EXPRESSION_HANDLER['raw']),
-    'file': (FileLoader, getKey),
-    'rawfolder': (FolderLoader, EXPRESSION_HANDLER['raw']),
-    'folder': (FolderLoader, getKey),
-}
-
-compiled_source_cache = {}
-class Recipe():
-
-    def _init(self, name, options):
-        self.once = options.get('once')
-        self.encoding = options.get('encoding', 'utf-8')
-        self._update = True
-        import_delimiter = options.get('import-delimiter',
-            DEFAULT_IMPORT_DELIMITER)
-        import_dict = {}
-        for line in options.get('import-list', '').splitlines(False):
-            if not line:
-                continue
-            expression_type, alias, expression = line.split(None, 2)
-            if alias in import_dict:
-                raise ValueError('Duplicate import-list entry %r' % alias)
-            loader_type, expression_handler = LOADER_TYPE_DICT[
-                expression_type]
-            import_dict[alias] = loader_type(
-                expression_handler(expression, *args),
-                import_delimiter, self.encoding,
-            )
-        if import_dict:
-            loader = RelaxedPrefixLoader(import_dict,
-                delimiter=import_delimiter)
-        else:
-            loader = None
-        self.template = options['url']
-        extension_list = [x for x in (y.strip()
-            for y in options.get('extensions', '').split()) if x]
-        self.context = options['context']
-        self.context.update(DEFAULT_CONTEXT.copy())
-        self.env = Environment(
-            extensions=extension_list,
-            undefined=StrictUndefined,
-            loader=loader)
-
-    def _render(self):
-        env = self.env
-        template = self.template
-        with open(template, 'rb') as f:
-          source = f.read().decode(self.encoding)
-        compiled_source_cache[template] = compiled_source = \
-            env.compile(source, filename=template)
-
-        template_object = env.template_class.from_code(env,
-            compiled_source,
-            env.make_globals(None), None)
-        print(self.context)
-        return template_object.render(**self.context).encode(self.encoding)
-
-    def install(self):
-        once = self.once
-        if once and os.path.exists(once):
-            return
-        installed = super(Recipe, self).install()
-        if once:
-            open(once, 'ab').close()
-            return
-        return installed
-
-    def update(self):
-        if self._update:
-            self.install()
-        else:
-            super(Recipe, self).update()
-
-r = Recipe()
-r._init("recipe", {
-  'extensions': 'jinja2.ext.do',
-  'url': 'config/{}.jinja2.cfg'.format(config),
-  'output': 'config/{}.cfg'.format(config),
-  'context': json.loads(json_params),
-  })
-with open('config/{}.cfg'.format(config), 'w+') as f:
-  f.write(r._render().decode())
+j2render(config, json_params)