docs: improve config example

separate sections for required/optional config settings

Signed-off-by: Christopher Arndt <chris@chrisarndt.de>

Dockerfile

@@ -1,5 +1,5 @@
 FROM python:3.11-alpine
-RUN python3 -m pip --no-cache-dir install markdown matrix-nio
+RUN python3 -m pip --no-cache-dir install bleach jinja2 markdown matrix-nio
 ADD matrixchat-notify.py /bin/
 ADD matrixchat-notify-config.json /etc/
 RUN chmod +x /bin/matrixchat-notify.py

README.md

@@ -1,7 +1,14 @@
 # drone-matrixchat-notify
 
-A [drone.io] [plugin] to send notifications to Matrix chat rooms from
+[![MIT License](https://img.shields.io/github/license/SpotlightKid/drone-matrixchat-notify?label=License)](https://github.com/SpotlightKid/drone-matrixchat-notify/blob/master/LICENSE)
-CI pipeline steps.
+[![GitHub tag (with filter)](https://img.shields.io/github/v/tag/SpotlightKid/drone-matrixchat-notify?filter=v*.*.*&logo=github&label=Latest%20version)](https://github.com/SpotlightKid/drone-matrixchat-notify/tags)
+[![Docker image version](https://img.shields.io/docker/v/spotlightkid/drone-matrixchat-notify?logo=docker&label=Docker+image)](https://hub.docker.com/r/spotlightkid/drone-matrixchat-notify)
+[![GitHub stars](https://img.shields.io/github/stars/SpotlightKid/drone-matrixchat-notify?logo=github&label=GitHub)](https://github.com/SpotlightKid/drone-matrixchat-notify)
+[![GitLab stars](https://img.shields.io/gitlab/stars/SpotlightKid%2Fdrone-matrixchat-notify?logo=gitlab&label=GitLab)](https://gitlab.com/SpotlightKid/drone-matrixchat-notify)
+[![GitHub issues](https://img.shields.io/github/issues/SpotlightKid/drone-matrixchat-notify?logo=github&label=Issues)](https://github.com/SpotlightKid/drone-matrixchat-notify/issues)
+
+A [drone.io] [plugin] to send notifications to Matrix chat rooms from CI
+pipeline steps. Supports *Jinja* message templates and *Markdown* rendering.
 
 Example pipeline configuration:
 
@@ -24,16 +31,54 @@ steps:
     userid: '@drone-bot@matrix.org'
     password:
       from_secret: drone-bot-pw
-    template: '${DRONE_REPO} ${DRONE_COMMIT_SHA} ${DRONE_BUILD_STATUS}'
+    markdown: 'yes'
+    template: |
+      `${DRONE_REPO}` build #${DRONE_BUILD_NUMBER} status: **${DRONE_BUILD_STATUS}**
+
+      ${DRONE_PULL_REQUEST_TITLE}](${DRONE_COMMIT_LINK})
 ```
 
 ## Configuration settings
 
-* `accesstoken`
+### Required
+
+* `roomid` *(required)*
+
+    ID of matrix chat room to send messages to (ID, not alias).
+
+* `userid` *(required)*
+
+    Matrix user ID on homeserver to send message as (ID, not username).
+
+* `password` *(required)*
+
+    Password to use for authenticating the user set with `userid`. Either a
+    password or an access token is required.
+
+* `accesstoken` *(required)*
 
     Access token to use for authentication instead of `password`. Either an
     access token or a password is required.
 
+### Optional
+
+* `allowed_attrs` *(default:* [`DEFAULT_ALLOWED_ATTRS`]*)*
+
+    List or string with comma-separated list of HTML attribute names or
+    dict mapping tag names to lists of attributes names.
+
+    See the bleach documentation on [allowed attributes] for more information.
+
+* `allowed_tags` *(default:* [`DEFAULT_ALLOWED_TAGS`]*)*
+
+    List or set or string with comma-separated list of HTML tag names. HTML
+    tags not included will be stripped from the HTML output generated by
+    rendering a Markdown message template.
+
+    Note that the default list does not include any tags, which allow to load
+    external resources when the generated HTML is displayed, notably `img`
+    is not included.
+
 * `deviceid`
 
     Device ID to send with access token.
@@ -46,34 +91,59 @@ steps:
 
     The Matrix homeserver URL.
 
+* `jinja`
+
+    If set to `yes`, `y`, `true`, `t`, `on` or `1`, the message template is
+    rendered with the [Jinja] templating engine (instead of performing simple
+    placeholder substitution). The template context is controlled by the
+    `pass_environment` setting, same as with non-Jinja templates, but
+    placeholders use a different syntax (example: `{{DRONE_REPO}}`), so the
+    `template` setting should be changed to be a valid Jinja template string
+    when this is enabled.
+
+    Using this feature requires the `jinja2` Python module to be available
+    (it is installed by default in the plugin's docker image).
+
 * `markdown`
 
-    If set to `yes`, `y`, `true` or `on`, the message resulting from template
+    If set to `yes`, `y`, `true`, `t`, `on` or `1`, the message resulting from
-    substtution is considered to be in Markdown format and will be rendered to
+    template substtution is considered to be in Markdown format and will be
-    HTML and sent as a formatted message with `org.matrix.custom.html` format.
+    rendered to HTML and sent as a formatted message with the format set to
+    `org.matrix.custom.html`.
 
-* `password`
+    Using this feature requires the `markdown` and `bleach` Python modules to
+    be available (they are installed by default in the plugin's docker image).
 
-    Password to use for authenticating the user set with `userid`. Either a
+* `markdown_extensions` *(default:* `admonition, extra, sane_lists, smarty`)
-    password or an access token is required.
 
-* `roomid` *(required)*
+    Comma-separated list of enabled Markdown extensions. See this
+    [list of extensions] for valid extension names. Including an invalid
+    extension name in this list will disable Markdown rendering.
 
-    ID of matrix chat room to send messages to (ID, not alias).
+* `pass_environment` *(default:* `DRONE_*`*)*
+
+    Comma-separated white-list of environment variable names or name patterns.
+    Patterns are shell-glob style patterns and case-sensitive.
+
+    Only environment variables matching any of the given names or patterns will
+    be available as valid placeholders in the message template.
 
 * `template` *(default:* `${DRONE_BUILD_STATUS}`*)*
 
-    The message template. Valid placeholders of the form `${PLACEHOLDER}` will
+    The message template. Valid placeholders (example: `${DRONE_REPO}`) will be
-    be substituted with the values of the matching environment variables.
+    substituted with the values of the matching environment variables (subject
+    to filtering according to the `pass_environment` setting).
 
-    See this [reference] for environment variables available drone.io in CI
+    See this [reference] for environment variables available in drone.io CI
     pipelines.
 
-* `userid` *(required)*
-
-    ID of user on homeserver to send message as (ID, not username).
 
 
+[`DEFAULT_ALLOWED_ATTRS`]: https://github.com/SpotlightKid/drone-matrixchat-notify/blob/master/matrixchat-notify.py#L28
+[`DEFAULT_ALLOWED_TAGS`]: https://github.com/SpotlightKid/drone-matrixchat-notify/blob/master/matrixchat-notify.py#L35
+[allowed attributes]: https://bleach.readthedocs.io/en/latest/clean.html#allowed-attributes-attributes
 [drone.io]: https://drone.io/
+[jinja]: https://jinja.palletsprojects.com/
+[list of extensions]: https://python-markdown.github.io/extensions/
 [plugin]: https://docs.drone.io/plugins/overview/
-[reference]:  https://docs.drone.io/pipeline/environment/reference/
+[reference]: https://docs.drone.io/pipeline/environment/reference/

matrixchat-notify.py

@@ -3,13 +3,16 @@
 
 Requires:
 
-* <https://github.com/poljar/matrix-nio>
+* <https://pypi.org/project/matrix-nio>
+* Optional: <https://pypi.org/project/bleach/>
+* Optional: <https://pypi.org/project/Jinja2/>
 * Optional: <https://pypi.org/project/markdown/>
 
 """
 
 import argparse
 import asyncio
+import fnmatch
 import json
 import logging
 import os
@@ -22,14 +25,59 @@ from nio import AsyncClient, LoginResponse
 
 PROG = "matrixchat-notify"
 CONFIG_FILENAME = f"{PROG}-config.json"
-DEFAULT_TEMPLATE = "${DRONE_BUILD_STATUS}"
+DEFAULT_ALLOWED_ATTRS = {
+    "*": ["class"],
+    "a": ["href", "title"],
+    "abbr": ["title"],
+    "acronym": ["title"],
+    "img": ["alt", "src"],
+}
+DEFAULT_ALLOWED_TAGS = {
+    "a",
+    "abbr",
+    "acronym",
+    "b",
+    "blockquote",
+    "code",
+    "dd",
+    "div",
+    "dl",
+    "dt",
+    "em",
+    "h1",
+    "h2",
+    "h3",
+    "h4",
+    "h5",
+    "h6",
+    "i",
+    "li",
+    "ol",
+    "p",
+    "span",
+    "strong",
+    "table",
+    "td",
+    "th",
+    "thead",
+    "tr",
+    "ul",
+}
 DEFAULT_HOMESERVER = "https://matrix.org"
+DEFAULT_MARKDOWN_EXTENSIONS = "admonition, extra, sane_lists, smarty"
+DEFAULT_PASS_ENVIRONMENT = ["DRONE_*"]
+DEFAULT_TEMPLATE = "${DRONE_BUILD_STATUS}"
 SETTINGS_KEYS = (
+    "allowed_tags",
+    "allowed_attrs",
     "accesstoken",
     "deviceid",
     "devicename",
     "homeserver",
+    "jinja",
     "markdown",
+    "markdown_extensions",
+    "pass_environment",
     "password",
     "roomid",
     "template",
@@ -40,7 +88,7 @@ log = logging.getLogger(PROG)
 
 def tobool(s):
     try:
-        return strtobool(s)
+        return strtobool(str(s))
     except ValueError:
         return False
 
@@ -110,6 +158,78 @@ async def send_notification(config, message):
     await client.close()
 
 
+def get_template_context(config):
+    pass_environment = config.get("pass_environment", [])
+
+    if not isinstance(pass_environment, list):
+        pass_environment = [pass_environment]
+
+    patterns = []
+    for value in pass_environment:
+        # expand any comma-separated names/patterns
+        if "," in value:
+            patterns.extend([p.strip() for p in value.split(",") if p.strip()])
+        else:
+            patterns.append(value)
+
+    env_names = tuple(os.environ)
+    filtered_names = set()
+
+    for pattern in patterns:
+        filtered_names.update(fnmatch.filter(env_names, pattern))
+
+    return {name: os.environ[name] for name in tuple(filtered_names)}
+
+
+def render_message(config):
+    context = get_template_context(config)
+    template = config.get("template", DEFAULT_TEMPLATE)
+
+    if tobool(config.get("jinja")):
+        try:
+            from jinja2.sandbox import SandboxedEnvironment
+
+            env = SandboxedEnvironment()
+            return env.from_string(template).render(context)
+        except Exception as exc:
+            log.error("Could not render Jinja2 template: %s", exc)
+            return template
+    else:
+        return Template(template).safe_substitute(context)
+
+
+def render_markdown(message, config):
+    import bleach
+    import markdown
+
+    allowed_attrs = config.get("allowed_attrs", DEFAULT_ALLOWED_ATTRS)
+    allowed_tags = config.get("allowed_tags", DEFAULT_ALLOWED_TAGS)
+    extensions = config.get("markdown_extensions", DEFAULT_MARKDOWN_EXTENSIONS)
+
+    if isinstance(allowed_attrs, str):
+        allowed_attrs = [attr.strip() for attr in allowed_attrs.split(",") if attr.strip()]
+
+    if isinstance(allowed_tags, str):
+        allowed_tags = [tag.strip() for tag in allowed_tags.split(",") if tag.strip()]
+
+    if isinstance(extensions, str):
+        extensions = [ext.strip() for ext in extensions.split(",") if ext.strip()]
+
+    try:
+        md = markdown.Markdown(extensions=extensions)
+    except (AttributeError, ImportError, TypeError) as exc:
+        log.error("Could not instantiate Markdown formatter: %s", exc)
+        return message
+
+    return {
+        "formatted_body": bleach.clean(
+            md.convert(message), tags=allowed_tags, attributes=allowed_attrs, strip=True
+        ),
+        "body": message,
+        "format": "org.matrix.custom.html",
+    }
+
+
 def main(args=None):
     ap = argparse.ArgumentParser(prog=PROG, description=__doc__.splitlines()[0])
     ap.add_argument(
@@ -125,6 +245,17 @@ def main(args=None):
         action="store_true",
         help="Don't send notification message, only print it.",
     )
+    ap.add_argument(
+        "-e",
+        "--pass-environment",
+        nargs="*",
+        help=(
+            "Comma-separated white-list of environment variable names or name patterns. Only "
+            "environment variables matching any of  the given names or patterns will be available "
+            "as valid placeholders in the message template. "
+            "Accepts shell glob patterns and may be passed more than once (default: 'DRONE_*')."
+        ),
+    )
     ap.add_argument(
         "-m",
         "--render-markdown",
@@ -141,9 +272,7 @@ def main(args=None):
     args = ap.parse_args(args)
 
     logging.basicConfig(
-        level=getattr(
+        level="DEBUG" if args.verbose else os.environ.get("PLUGIN_LOG_LEVEL", "INFO").upper(),
-            logging, "DEBUG" if args.verbose else os.environ.get("PLUGIN_LOG_LEVEL", "INFO")
-        ),
         format=os.environ.get("PLUGIN_LOG_FORMAT", "%(levelname)s: %(message)s"),
     )
 
@@ -152,23 +281,22 @@ def main(args=None):
     except Exception as exc:
         return f"Could not parse configuration: {exc}"
 
-    template = config.get("template", DEFAULT_TEMPLATE)
+    if args.pass_environment is not None:
-    message = Template(template).safe_substitute(os.environ)
+        # Security feature: if any environment names/patterns are passed via -e|--pass-environment
+        # options, they completely replace any given via the config or environment.
+        config["pass_environment"] = args.pass_environment
+
+    if "pass_environment" not in config:
+        config["pass_environment"] = DEFAULT_PASS_ENVIRONMENT
+
+    message = render_message(config)
 
     if tobool(config.get("markdown")) or args.render_markdown:
         log.debug("Rendering markdown message to HTML.")
         try:
-            import markdown
+            message = render_markdown(message, config)
-
-            formatted = markdown.markdown(message)
         except:  ## noqa
             log.exception("Failed to render message with markdown.")
-            return 1
-
-        body = message
-        message = {"formatted_body": formatted}
-        message["body"] = body
-        message["format"] = "org.matrix.custom.html"
 
     if not args.dry_run:
         if not config.get("userid"):