大抵の突然のわけの分からない不具合はSELINUXを禁止すると治る

今までに何回わけの分からない不具合がこれだったか…。

ほとんどの場合は、POSIXのファイルパーミッションでは不可思議な現象に関連していたが、今回はFedora 20で新しいサーバを構築中に起こった。

下は yum  実行時に起きたわけの分からないエラーメッセージ。リポジトリサーバがダウンしていたのかと思い半日待ったが埒があかない。「まさか」と思いつつ /etc/selinux/config で「SELINUX=disabled」にしたらあっけなく治った。

[root@mill3 ~]# yum makecache Loaded plugins: langpacks, refresh-packagekit  One of the configured repositories failed (Unknown),  and yum doesn't have enough cached data to continue. At this point the only  safe thing yum can do is fail. There are a few ways to work "fix" this:      1. Contact the upstream for the repository and get them to fix the problem.      2. Reconfigure the baseurl/etc. for the repository, to point to a working         upstream. This is most often useful if you are using a newer         distribution release than is supported by the repository (and the         packages for the previous distribution release still work).      3. Disable the repository, so yum won't use it by default. Yum will then         just ignore the repository until you permanently enable it again or use         --enablerepo for temporary usage:             yum-config-manager --disable <repoid>      4. Configure the failing repository to be skipped, if it is unavailable.         Note that yum will try to contact the repo. when it runs most commands,         so will have to try and fail each time (and thus. yum will be be much         slower). If it is a very temporary problem though, this is often a nice         compromise:             yum-config-manager --save --setopt=<repoid>.skip_if_unavailable=true Cannot retrieve metalink for repository: fedora/20/x86_64. Please verify its path and try again

SELINUX は本当に質（たち）が悪い。