基于CUPS实现云打印平台
今年在员工服务台上线了云打印功能，不少小伙伴私下联系好奇是如何实现的，连公司打印机供应商都惊动了，于是去翻了下笔记，单开一篇文档简单说明下实现过程吧，
设计思路
CUPS（Common UNIX Printing System，通用 UNIX 打印系统）是一个开源的打印系统，通过实现标准的打印协议（如 IPP）以及提供强大的管理工具，为用户和管理员简化打印任务的配置和管理。本服务主要是依赖CUPS打印服务实现，大致设计思路如下：
用户前端浏览器上传文件，发送文件及打印参数至后端接口
后端接收文件和打印参数，创建打印任务队列调用打印工具类lp
通过lp命令发送文件至cups服务器实现打印
业务流程图和前端页面：
打印服务端实现
安装cups和过滤器依赖
# 我这里使用的是1.6.3版本，openprinting最新版本是2.4，这个版本耦合性太强，安装filters时编译复杂，太多依赖需要手动安装，这里功能不需要太复杂，故而选择旧版本
yum install -y cups foomatic-filters编辑配置
/etc/cups/cupsd.conf
Listen 0.0.0.0:631
# 增加Allow all
# Restrict access to the server...
<Location />
Allow all
Order allow,deny
</Location>
# Restrict access to the admin pages...
<Location /admin>
Allow all
AuthType Default
Require user @SYSTEM
Order allow,deny
</Location>
# Restrict access to configuration files...
<Location /admin/conf>
Allow all
AuthType Default
Require user @SYSTEM
Order allow,deny
</Location>重启服务
systemctl restart cups下载打印机ppd驱动描述文件
[理光打印机] https://www.openprinting.org/download/PPD/Ricoh/PS/
[其他型号] https://www.openprinting.org/download/PPD/
回到CUPS管理后台，添加打印机
打印命令配置测试
使用lp打印命令测试驱动配置，打印选项根据机型和驱动版本有所不同，具体参数可使用lpoptions -d -l printername查看
理光
# 页面自适应
-o fit-to-page
# 打印份数
-o copies=1
# 颜色模式:Gray黑白，CMYK彩色
-o ColorModel=Gray/CMKY
# 双面模式：None关闭，DuplexNoTumble长边翻转，DuplexTumble短边翻转
-o Duplex=None/DuplexNoTumble/DuplexTumble
# 横向打印，仅文本模式
-o landscape
# 双面模式：one-sided单面，two-sided-long-edge双面长边翻转
-o sides=one-sided/two-sided-long-edge震旦（仅差异部分）
#颜色模式：Grayscale黑白，Color彩色
-o SelectColor=Grayscale/Color后端接口实现
class PrintJobSerializer(serializers.Serializer):
"""
打印接口序列化器
*cups_server：cups服务器和端口号，例127.0.0.1:631
*printer_name：cups中打印机的名称
*file：打印文件
copies：打印份数，默认为1
duplex：双面参数，默认为双面长边翻转（one-sided单面；two-sided-long-edge双面长边翻转）
landscape：打印方向，默认为纵向。（True横向；False纵向）
page_range：页码范围，默认打印全部
color_mode：色彩模式，默认黑白（Gray黑白；CMYK彩色）
fit_to_page：页面缩放，默认为填充（True填充；False原始比例）
"""
cups_server = serializers.CharField(required=True)
printer_name = serializers.CharField(required=True)
file = serializers.ListField(child=serializers.FileField(), required=True)
copies = serializers.IntegerField(default=1)
duplex = serializers.CharField(default="two-sided-long-edge")
landscape = serializers.BooleanField(default=False)
page_range = serializers.CharField(default=None)
color_mode = serializers.CharField(default="Gray")
fit_to_page = serializers.BooleanField(default=True)
class PrintJobView(APIView):
authentication_classes = []
def post(self, request, *args, **kwargs):
serializer = PrintJobSerializer(data=request.data)
if serializer.is_valid():
files = serializer.validated_data['file']
files_path = []
for file in files:
random_filename = str(uuid.uuid4()) + '_' + os.path.basename(file.name)
file_path = os.path.join('media', random_filename)
files_path.append(file_path)
with open(file_path, 'wb') as destination:
for chunk in file.chunks():
destination.write(chunk)
try:
print_job_command = [
"lp",
"-h", str(serializer.validated_data['cups_server']),
"-d", serializer.validated_data['printer_name'],
"-n", str(serializer.validated_data['copies']),
"-o", f"sides={serializer.validated_data['duplex']}",
"-o", f"ColorModel={serializer.validated_data['color_mode']}",
]
if serializer.validated_data['landscape']:
print_job_command.extend(["-o", "landscape"])
if serializer.validated_data['fit_to_page']:
print_job_command.extend(["-o", "fit-to-page"])
if serializer.validated_data.get('page_range'):
print_job_command.extend(["-o", f"page-ranges={serializer.validated_data['page_range']}"])
for command_file_path in files_path:
print_job_command.append(command_file_path)
result = subprocess.run(print_job_command, capture_output=True, text=True, shell=True)
# 生产环境需要去掉shell=True，否则无法打印
# result = subprocess.run(print_job_command, capture_output=True, text=True)
if result.returncode != 0:
raise CalledProcessError(result.returncode, result.args, output=result.stdout, stderr=result.stderr)
match = re.search(r'request id is (\S+)', result.stdout)
if match:
print_id = match.group(1)
for file in files_path:
os.remove(file)
return Response({"code": return_code.SUCCESS, "print_id": print_id, })
return Response({"code": return_code.SUCCESS, "print_id": None, })
except CalledProcessError as e:
for file in files_path:
os.remove(file)
return Response({"code": return_code.ERROR, "error": f"{e.stderr}"})
else:
return Response({"code": return_code.ERROR, "error": serializer.errors})