Generated systemd service contains line that is too long

[Gohla]

I'm setting up a Jenkins instance on a nixos server, which works with default settings. However, if I add more package dependencies to the configuration, the generated systemd service file contains a line that is too long, and systemd cannot parse it any more.

The configuration is:

services.jenkins = {
  enable = true;
  home = "/home/jenkins";
  packages = [ pkgs.stdenv pkgs.git pkgs.oraclejdk7 pkgs.openssh pkgs.nix pkgs.gnutar pkgs.gzip pkgs.bash pkgs.maven pkgs.wget pkgs.unzip pkgs.ant ];
};

This is the generated service file:

[Unit]
After=network.target
Description=Jenkins Continuous Integration Server

[Service]
Environment="JENKINS_HOME=/home/jenkins"
Environment="LOCALE_ARCHIVE=/nix/store/5jxnz56h6ya1wy0dvcll65vkkx9679g4-glibc-locales-2.19/lib/locale/locale-archive"
Environment="NIX_REMOTE=daemon"
Environment="PATH=/nix/store/rq16hrf7gy426a6lcnf6pa9746sxnbgc-stdenv/bin:/nix/store/fqh4k92hghc190lhkqxrgpz1gj3l1zqi-git-1.9.4/bin:/nix/store/6r4ndcffxq5bc8lddycakvbp80l4sxij-jdk-1.7.0_55/bin:/nix/store/2wc50fcn54axkg2kk71jm2r5h0w5rbh6-openssh-6.6p1/bin:/nix/store/9f0n3pzmvv76p33m6rjck4gvifvl87ba-nix-1.7/bin:/nix/store/0x21z9gqd3rdhxffhxdaf1ccilaay4s4-gnutar-1.27.1/bin:/nix/store/asnkw21m4y0ihphnxi8wvw9f45f0d83k-gzip-1.6/bin:/nix/store/p0vd3ydvxplbpjffkpblwj5dahcmp9ri-bash-4.2-p45/bin:/nix/store/amwc7axnc8hi4dpbbsyrn36zq458yhxy-apache-maven-3.0.4/bin:/nix/store/rkhsvhrf6jhc5gl2638j55ap9lqrkfli-wget-1.15/bin:/nix/store/bhkglf9hbr8pbnqbbpszc65r5sh64f06-unzip-6.0/bin:/nix/store/jg2h4bhq4k0mm0wzk69bj9y5bq6xyjb8-ant-1.9.3/bin:/nix/store/xdswdgz11w9lm9n9bzb6spl7dj45s2x2-coreutils-8.21/bin:/nix/store/sls52f6fkpqfs0kj4w0k525v57zrsz9x-findutils-4.4.2/bin:/nix/store/937i66g191shz0hwzll61vmi0zvy3gwy-gnugrep-2.14/bin:/nix/store/93wabgii15q4d74fqgcpfka1qy42igr4-gnused-4.2.2/bin:/nix/store/x0knwlax0d250bqm97lwi7yaqq1lkypf-systemd-212/bin:/nix/store/rq16hrf7gy426a6lcnf6pa9746sxnbgc-stdenv/sbin:/nix/store/fqh4k92hghc190lhkqxrgpz1gj3l1zqi-git-1.9.4/sbin:/nix/store/6r4ndcffxq5bc8lddycakvbp80l4sxij-jdk-1.7.0_55/sbin:/nix/store/2wc50fcn54axkg2kk71jm2r5h0w5rbh6-openssh-6.6p1/sbin:/nix/store/9f0n3pzmvv76p33m6rjck4gvifvl87ba-nix-1.7/sbin:/nix/store/0x21z9gqd3rdhxffhxdaf1ccilaay4s4-gnutar-1.27.1/sbin:/nix/store/asnkw21m4y0ihphnxi8wvw9f45f0d83k-gzip-1.6/sbin:/nix/store/p0vd3ydvxplbpjffkpblwj5dahcmp9ri-bash-4.2-p45/sbin:/nix/store/amwc7axnc8hi4dpbbsyrn36zq458yhxy-apache-maven-3.0.4/sbin:/nix/store/rkhsvhrf6jhc5gl2638j55ap9lqrkfli-wget-1.15/sbin:/nix/store/bhkglf9hbr8pbnqbbpszc65r5sh64f06-unzip-6.0/sbin:/nix/store/jg2h4bhq4k0mm0wzk69bj9y5bq6xyjb8-ant-1.9.3/sbin:/nix/store/xdswdgz11w9lm9n9bzb6spl7dj45s2x2-coreutils-8.21/sbin:/nix/store/sls52f6fkpqfs0kj4w0k525v57zrsz9x-findutils-4.4.2/sbin:/nix/store/937i66g191shz0hwzll61vmi0zvy3gwy-gnugrep-2.14/sbin:/nix/store/93wabgii15q4d74fqgcpfka1qy42igr4-gnused-4.2.2/sbin:/nix/store/x0knwlax0d250bqm97lwi7yaqq1lkypf-systemd-212/sbin"



ExecStart=/nix/store/n2disw6k70h64pyzdhx8bcqbq96yajjp-unit-script/bin/jenkins-start
ExecStartPost=/nix/store/hgjsm80npdmkvx737y0bxcm5kdzd0liz-unit-script/bin/jenkins-post-start
User=jenkins

If I try to start this service, I get the error:

Failed to start jenkins.service: Unit jenkins.service failed to load: Bad message. See system logs and 'systemctl status jenkins.service' for details.

The logs contain:

systemd[1]: [/nix/store/ha60ypzklhj6anrrz8aqrjlgfhrvhrwf-unit/jenkins.service:10] Missing '='.

The line with the PATH environment is 2080 characters. According to someone from the #systemd IRC channel, the systemd parser only handles lines up to LINE_MAX which POSIX sets to 2048 by default. It is possible to break up the line by using the regular '', but since the service file is generated and cannot be changed, the generator needs to break up lines.

On a side note, the path also contains each entry twice, taking up even more space.

[Gohla]

cstrahan on the #nixos IRC channel showed me a workaround, create an environment with all the required packages and use that instead:

services.jenkins.packages =
  let env = pkgs.buildEnv {
    name = "jenkins-env";
    pathsToLink = [ "/bin" ];
    paths = [
      # defaults
      pkgs.stdenv pkgs.git pkgs.jdk pkgs.openssh pkgs.nix
      # put your packages here:
      # ...
    ];
  };
  in [ env ];

[domenkozar]

@Gohla in 9956b97 we check for length now, that's pretty much what can be done.