Add a renderer for log files that can render ansi colours

airlock/renderers.py

@@ -2,16 +2,19 @@
 
 import csv
 import mimetypes
+import re
 from dataclasses import dataclass
 from email.utils import formatdate
 from functools import cached_property
 from io import BytesIO, StringIO
 from pathlib import Path
 from typing import IO, Any, ClassVar, Self, cast
 
+from ansi2html import Ansi2HTMLConverter
 from django.http import FileResponse, HttpResponseBase
 from django.template import Template, loader
 from django.template.response import SimpleTemplateResponse
+from django.utils.safestring import mark_safe
 
 from airlock.types import UrlPath
 from airlock.utils import is_valid_file_type
@@ -158,9 +161,35 @@ def context(self):
         }
 
 
+class LogRenderer(TextRenderer):
+    def context(self):
+        # Convert the text of the log file to HTML, converting ANSI colour codes to css classes
+        # so we get the colour formatting from the original log.
+        # We don't need the full HTML file that's produced, so just extract the <pre></pre>
+        # tag which contains the log content and the inline styles.
+        conv = Ansi2HTMLConverter()
+        text = conv.convert(self.stream.read())
+        match = re.match(
+            r".*(?P<style_tag><style.*</style>).*(?P<pre_tag><pre.*</pre>).*",
+            text,
+            flags=re.S,
+        )
+        if match:  # pragma: no branch
+            # After conversion, we should always find a match. As a precaution, check
+            # and render the plain text if we don't.
+            style_tag = match.group("style_tag")
+            pre_tag = match.group("pre_tag")
+            text = mark_safe(f"{style_tag}{pre_tag}")
+
+        return {
+            "text": text,
+            "class": Path(self.filename).suffix.lstrip("."),
+        }
+
+
 FILE_RENDERERS = {
     ".csv": CSVRenderer,
-    ".log": TextRenderer,
+    ".log": LogRenderer,
     ".txt": TextRenderer,
     ".json": TextRenderer,
     ".md": TextRenderer,

requirements.prod.in

@@ -1,3 +1,4 @@
+ansi2html
 Django
 django-vite
 slippers

requirements.prod.txt

@@ -4,6 +4,10 @@
 #
 #    pip-compile --allow-unsafe --generate-hashes --strip-extras requirements.prod.in
 #
+ansi2html==1.9.2 \
+    --hash=sha256:3453bf87535d37b827b05245faaa756dbab4ec3d69925e352b6319c3c955c0a5 \
+    --hash=sha256:dccb75aa95fb018e5d299be2b45f802952377abfdce0504c17a6ee6ef0a420c5
+    # via -r requirements.prod.in
 asgiref==3.8.1 \
     --hash=sha256:3e1e3ecc849832fe52ccf2cb6686b7a55f82bb1d6aee72a58826471390335e47 \
     --hash=sha256:c343bd80a0bec947a9860adb4c432ffa7db769836c64238fc34bdc3fec84d590

tests/unit/test_renderers.py

@@ -12,10 +12,12 @@
     (".png", "image/png", False, None),
     (".csv", "text/html", False, "airlock/templates/file_browser/csv.html"),
     (".txt", "text/html", False, "airlock/templates/file_browser/text.html"),
+    (".log", "text/html", False, "airlock/templates/file_browser/text.html"),
     (".html", "text/html", True, "airlock/templates/file_browser/plaintext.html"),
     (".png", "text/html", True, "airlock/templates/file_browser/plaintext.html"),
     (".csv", "text/html", True, "airlock/templates/file_browser/plaintext.html"),
     (".txt", "text/html", True, "airlock/templates/file_browser/plaintext.html"),
+    (".log", "text/html", True, "airlock/templates/file_browser/plaintext.html"),
 ]
 
 
@@ -145,3 +147,27 @@ def test_plaintext_renderer_handles_invalid_utf8(tmp_path):
     response.render()
     assert response.status_code == 200
     assert "invalid � continuation byte" in response.rendered_content
+
+
+def test_log_renderer_handles_ansi_colors(tmp_path):
+    log_file = tmp_path / "test.log"
+    # in ansi codes:
+    # \x1B[32m = foregrouund green
+    # \x1b[1m bold
+    # \x1b[0m resets formatting
+    log_file.write_bytes(
+        b"No ansi here \x1b[32m\x1b[1mThis is green and bold.\x1b[0m This is not."
+    )
+    relpath = log_file.relative_to(tmp_path)
+    Renderer = renderers.get_renderer(relpath)
+    renderer = Renderer.from_file(log_file, relpath)
+    response = renderer.get_response()
+    response.render()
+    assert response.status_code == 200
+
+    assert "ansi1 { font-weight: bold; }" in response.rendered_content
+    assert "ansi32 { color: #00aa00; }" in response.rendered_content
+    assert (
+        '<span class="ansi1 ansi32">This is green and bold.</span>'
+        in response.rendered_content
+    )