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dnf-json: convert to single-use depsolve script

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- Removed server class and handlers
    The dnf-json Python script will no longer run as a service.  In the
    future, we will create a service in the Go package that will handle
    receiving requests and calling the script accordingly.
- Removed CacheState class
- Added standalone functions for setting up cache and running the
  depsolve
- Validate the input before reading
- Print all messages (status and error) to stderr and print only the
  machine-readable results to stdout (including structured error)
    The status messages on stderr are useful for troubleshooting.  When
    called from the service they will appear in the log/journal.
- Catch RepoError exceptions
    This can occur when dnf fails to load the repository configuration.
- Support multiple depsolve jobs per request
    The structure is changed to support making multiple depsolve
    requests but reuse the dnf.Base object to make chained (incremental)
    dependency resolution requests.

Before:
{
  "command": "depsolve",
    "arguments": {
      "package-specs": [...],
      "exclude-specs": [...],
      "repos": [{...}],
      "cachedir": "...",
      "module_platform_id": "...",
      "arch": "..."
    }
}

After:
{
  "command": "depsolve",
  "cachedir": "...",
  "module_platform_id": "...",
  "arch": "...",
  "arguments": {
    "repos": [{...}],
    "transactions": [
      {
        "package-specs": [...],
        "exclude-specs": [...],
        "repo-ids": [...]
      }
    ]
  }
}

Signed-off-by: Achilleas Koutsou <achilleas@koutsou.net>
This commit is contained in:
Achilleas Koutsou 2022-03-18 16:43:46 +01:00 • committed by Tom Gundersen
parent 4b289ce861
commit 82007dcf46
1 changed files with 142 additions and 233 deletions
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375
dnf-json
View file

@ -1,95 +1,25 @@
#!/usr/bin/python3 #!/usr/bin/python3
# pylint: disable=invalid-name # pylint: disable=invalid-name
"""
A JSON-based interface for depsolving using DNF.
Reads a request through stdin and prints the result to stdout.
Status messages are always printed to stderr.
In case of error, a structured error is printed to stdout as well.
"""
import hashlib import hashlib
import json import json
import logging
import os import os
import pickle
import shutil
import socket
import socketserver
import sys import sys
import tempfile import tempfile
from datetime import datetime
from datetime import datetime, timedelta
from http.server import BaseHTTPRequestHandler
from multiprocessing import Lock
import dnf import dnf
import hawkey import hawkey
# Logging setup (to systemd if available)
formatter = logging.Formatter(
fmt="%(asctime)s %(name)s.%(levelname)s: %(message)s",
datefmt="%Y.%m.%d %H:%M:%S"
)
handler = logging.StreamHandler(stream=sys.stdout)
handler.setFormatter(formatter)
log = logging.getLogger('dnf-json')
log.addHandler(handler)
log.setLevel(logging.INFO)
# Synchronisation necessary for the multiprocess request handling.
process_lock = Lock()
class CacheState():
"""
A CacheState keeps track of the cache folders.
CacheState objects can update the list of used cache folders, which
will associate a date object to the name of the folder.
CacheState objects can ask to clean the unused cache folders.
Meaning that the folders having reach a certain timeout will be deleted.
"""
def __init__(self, cache_dir, cache_timeout, folder_dict=None):
"""
cache_dir the place where the state is stored
folder_dict a dict containing the existing list of cache folders
cache_timeout a timedelta before a cache folder can be deleted
"""
if folder_dict is None:
folder_dict = {}
self.cache_dir = cache_dir
self.folder_dict = folder_dict
self.cache_timeout = cache_timeout
def update_used(self, folder):
"""
Associate a datetime.now() to the folders given as parameters
"""
log.debug("Folder %s was used", folder)
self.folder_dict[folder] = datetime.now()
def clean_unused(self):
"""
Delete the folders having reach the timeout
"""
log.info("clean unused folders")
now = datetime.now()
list_folder_to_delete = []
for folder, then in self.folder_dict.items():
delta = now - then
log.debug("delete %s if %s > than %s", folder, delta, self.cache_timeout)
if delta > self.cache_timeout:
list_folder_to_delete.append(folder)
for folder in list_folder_to_delete:
del self.folder_dict[folder]
shutil.rmtree(folder)
@classmethod
def load(cls, cache_dir):
try:
with open(os.path.join(cache_dir, "cache_state.pkl"), "rb") as inp:
return pickle.load(inp)
except FileNotFoundError:
return cls(cache_dir, timedelta(hours=24))
def store(self):
with open(os.path.join(self.cache_dir, "cache_state.pkl"), "wb") as outp:
return pickle.dump(self, outp)
class Solver(): class Solver():
@ -256,7 +186,7 @@ class Solver():
# don't install weak-deps for transactions after the 1st transaction # don't install weak-deps for transactions after the 1st transaction
if idx > 0: if idx > 0:
self.base.conf.install_weak_deps=False self.base.conf.install_weak_deps = False
# set the packages from the last transaction as installed # set the packages from the last transaction as installed
for installed_pkg in last_transaction: for installed_pkg in last_transaction:
@ -266,7 +196,7 @@ class Solver():
self.base.install_specs( self.base.install_specs(
transaction.get("package-specs"), transaction.get("package-specs"),
transaction.get("exclude-specs"), transaction.get("exclude-specs"),
reponame=[str(id) for id in transaction.get("repos")]) reponame=[str(rid) for rid in transaction.get("repo-ids")])
self.base.resolve() self.base.resolve()
# store the current transaction result # store the current transaction result
@ -301,163 +231,142 @@ class Solver():
} }
class DnfJsonRequestHandler(BaseHTTPRequestHandler): def setup_cachedir(request):
""" arch = request["arch"]
Answers Http requests to depsolve or dump packages. # If dnf-json is run as a service, we don't want users to be able to set the cache
""" cache_dir = os.environ.get("OVERWRITE_CACHE_DIR", "")
if cache_dir:
cache_dir = os.path.join(cache_dir, arch)
else:
cache_dir = request.get("cachedir", "")
def __init__(self, *args, **kwargs): if not cache_dir:
self.cache_dir = None return "", {"kind": "Error", "reason": "No cache dir set"}
super().__init__(*args, **kwargs)
def init_cache_folder_list(self, repos): return cache_dir, None
cache_folders = []
for repo in repos:
if "baseurl" in repo:
url = repo["baseurl"]
elif "metalink" in repo:
url = repo["metalink"]
elif "mirrorlist" in repo:
url = repo["mirrorlist"]
else:
assert False
digest = hashlib.sha256(url.encode()).hexdigest()[:16]
repoid = repo["id"]
cache_folders.append(f"{self.cache_dir}/{repoid}-{digest}")
return cache_folders
def _send(self):
self.client_address = ('', 0)
def response_with_dnf_error(self, kind: str, reason: str):
self._send()
self.send_response(500)
self.send_header("Content-Type", "application/json")
self.end_headers()
self.wfile.write(json.dumps({"kind": kind, "reason":
reason}).encode("utf-8"))
def response_failure(self, json_object):
self._send()
self.send_response(500)
self.send_header("Content-Type", "application/json")
self.end_headers()
self.wfile.write(json.dumps(json_object).encode("utf-8"))
def response_success(self, json_object):
self._send()
self.send_response(200)
self.send_header("Content-Type", "application/json")
self.end_headers()
self.wfile.write(json.dumps(json_object).encode("utf-8"))
def do_POST(self):
"""
do_Post answer the request of a depsolving/dump.
Depsolving and dump require synchronizing caches on disk to perform their
operations. Caches folders are created for each remote repository. Since
the user request contains the list of repository the space taken can grow
indefinitely.
This solution implements a cache cleaning mechanism. It works by deleting
the directories on a timeout based rule and by keeping the last used date
in a synced file on disks.
This method is multiprocess safe.
"""
with process_lock:
try:
content_len = int(self.headers.get('Content-Length'))
data = self.rfile.read(content_len)
call = json.loads(data.decode("utf-8"))
command = call["command"]
arguments = call["arguments"]
repos = arguments.get("repos", {})
arch = arguments["arch"]
module_platform_id = arguments["module_platform_id"]
# If dnf-json is run as a service, we don't want users to be able to set the cache
self.cache_dir = os.environ.get("OVERWRITE_CACHE_DIR", "")
if self.cache_dir:
self.cache_dir = os.path.join(self.cache_dir, arch)
else:
self.cache_dir = arguments.get("cachedir", "")
if not self.cache_dir:
self.response_failure({"kind": "Error", "reason": "No cache dir set"})
cache_state = CacheState.load(self.cache_dir)
with tempfile.TemporaryDirectory() as persistdir:
try:
solver = Solver(
repos,
module_platform_id,
persistdir,
self.cache_dir,
arch
)
if command == "dump":
self.response_success(solver.dump())
log.info("dump success")
elif command == "depsolve":
self.response_success(
solver.depsolve(
arguments["package-specs"],
arguments.get("exclude-specs", [])
)
)
log.info("depsolve success")
elif command == "chain-depsolve":
self.response_success(
solver.chain_depsolve(arguments["transactions"])
)
except dnf.exceptions.MarkingErrors as e:
log.info("error install_specs")
self.response_with_dnf_error(
"MarkingErrors",
f"Error occurred when marking packages for installation: {e}"
)
except dnf.exceptions.DepsolveError as e:
log.info("error depsolve")
self.response_with_dnf_error(
"DepsolveError",
(
"There was a problem depsolving "
f"{arguments['package-specs']}: {e}"
)
)
except dnf.exceptions.Error as e:
self.response_with_dnf_error(
type(e).__name__,
f"Error occurred when setting up repo: {e}")
finally:
for cache_folder in self.init_cache_folder_list(repos):
cache_state.update_used(cache_folder)
cache_state.clean_unused()
cache_state.store()
log.info("Starting the dnf-json server") def solve(request, cache_dir):
command = request["command"]
arch = request["arch"]
module_platform_id = request["module_platform_id"]
arguments = request["arguments"]
LISTEN_FDS = int(os.environ.get("LISTEN_FDS", 0)) transactions = arguments.get("transactions")
# set from entrypoint if differs from 3 with tempfile.TemporaryDirectory() as persistdir:
LISTEN_FD = int(os.environ.get("LISTEN_FD", 3)) try:
solver = Solver(
arguments["repos"],
module_platform_id,
persistdir,
cache_dir,
arch
)
if command == "dump":
result = solver.dump()
printe("dump success")
elif command == "depsolve":
job = transactions[0]
result = solver.depsolve(
job["package-specs"],
job.get("exclude-specs", [])
)
printe("depsolve success")
elif command == "chain-depsolve":
result = solver.chain_depsolve(transactions)
printe("chain-depsolve success")
except dnf.exceptions.MarkingErrors as e:
printe("error install_specs")
return None, {
"kind": "MarkingErrors",
"reason": f"Error occurred when marking packages for installation: {e}"
}
except dnf.exceptions.DepsolveError as e:
printe("error depsolve")
return None, {
"kind": "DepsolveError",
"reason": f"There was a problem depsolving {arguments['package-specs']}: {e}"
}
except dnf.exceptions.RepoError as e:
return None, {
"kind": "RepoError",
"reason": f"There was a problem reading a repository: {e}"
}
except dnf.exceptions.Error as e:
printe("error repository setup")
return None, {
"kind": type(e).__name__,
"reason": str(e)
}
return result, None
# The dnf-json web server has to use forks to serve the requests. Because the def printe(*msg):
# dnf library is leaking memory in its Cpp side. print(*msg, file=sys.stderr)
class SystemDActivationSocketServer(socketserver.ForkingMixIn, socketserver.UnixStreamServer):
def server_bind(self):
log.debug("service bind")
log.debug("rebind socket")
log.debug("address_family: %d ", self.address_family)
log.debug("socket_type: %d ", self.socket_type)
if LISTEN_FDS > 1:
log.warning("More than one LISTEN_FDS")
self.socket = socket.fromfd(LISTEN_FD, self.address_family, self.socket_type)
# start the web server def fail(err):
server = SystemDActivationSocketServer('', DnfJsonRequestHandler) printe(f"{err['kind']}: {err['reason']}")
server.serve_forever() print(json.dumps(err))
sys.exit(1)
def respond(result):
print(json.dumps(result))
def validate_request(request):
command = request.get("command")
valid_cmds = ("depsolve", "dump", "chain-depsolve")
if command not in valid_cmds:
return {
"kind": "InvalidRequest",
"reason": f"invalid command '{command}': must be one of {', '.join(valid_cmds)}"
}
if not request.get("arch"):
return {
"kind": "InvalidRequest",
"reason": "no 'arch' specified"
}
if not request.get("module_platform_id"):
return {
"kind": "InvalidRequest",
"reason": "no 'module_platform_id' specified"
}
arguments = request.get("arguments")
if not arguments:
return {
"kind": "InvalidRequest",
"reason": "empty 'arguments'"
}
if not arguments.get("repos"):
return {
"kind": "InvalidRequest",
"reason": "no 'repos' specified"
}
return None
def main():
request = json.load(sys.stdin)
err = validate_request(request)
if err:
fail(err)
cachedir, err = setup_cachedir(request)
if err:
fail(err)
result, err = solve(request, cachedir)
if err:
fail(err)
else:
respond(result)
if __name__ == "__main__":
main()