Package: apt Version: 2.5.2 Severity: important Moin
apt considers all hard DNS errors (NXDOMAIN), aka EAI_NONAME from getaddrinfo, as transient and retries. Example response from the http method: | 400 URI Failure | Transient-Failure: true | FailReason: ResolveFailure | Message: Could not resolve 'test.example.com' | URI: https://test.example.com/debian/dists/experimental/InRelease Responsible code seems to be methods/connect.cc:ConnectToHostname. So if you use apt-transport-mirror, specifying a non-resolving name just forces a retry, four time, before it can go to the backup mirror. This means an additional five seconds is added to every download. It get's a bit complicated, as a SERVFAIL response from DNS seems to provoke an EAI_NONAME error as well, as can be easily checked with dnssec-failed.org. But as SERVFAIL only gets out if the DNS resolver already hit an unrecoverable error during it's one retries or something like broken signatures, retrying is also not really useful. Back story: For the cloud images we think about specifying something like this via apt-transport-mirror if the user does not define anything different: | https://vendor.deb.debian.cloud priority:1 | https://deb.debian.org This will force a fallback to deb.debian.org if the other one does not work. This is meant to be used only if hell breaks loose, so is a last resort fallback. However just killing the DNS records for the first listed one does produce a lot of retries because of the described behaviour. -- System Information: Debian Release: bookworm/sid APT prefers testing APT policy: (990, 'testing'), (500, 'unstable'), (500, 'stable'), (1, 'experimental') Architecture: amd64 (x86_64) Kernel: Linux 5.19.0-trunk-amd64 (SMP w/12 CPU threads; PREEMPT) Locale: LANG=de_DE.UTF-8, LC_CTYPE=de_DE.UTF-8 (charmap=UTF-8), LANGUAGE not set Shell: /bin/sh linked to /usr/bin/dash Init: systemd (via /run/systemd/system) Versions of packages apt depends on: ii adduser 3.123 ii debian-archive-keyring 2021.1.1 ii gpgv 2.2.35-3 ii libapt-pkg6.0 2.5.2 ii libc6 2.34-3 ii libgcc-s1 12.1.0-8 ii libgnutls30 3.7.7-2 ii libseccomp2 2.5.4-1+b1 ii libstdc++6 12.1.0-8 ii libsystemd0 251.3-1 Versions of packages apt recommends: ii ca-certificates 20211016 Versions of packages apt suggests: pn apt-doc <none> pn aptitude | synaptic | wajig <none> ii dpkg-dev 1.21.9 ii gnupg 2.2.35-3 pn powermgmt-base <none> -- no debconf information
