113 lines
5.0 KiB
Bash
113 lines
5.0 KiB
Bash
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# This script is intended to be run during container-image build. Any
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# other usage outside this context is likely to cause harm.
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set -eo pipefail
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for varname in PRUNE_INTERVAL RUNNER_VERSION TARGETARCH; do
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if [[ -z "${!varname}" ]]; then
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echo "Error: \$$varname must be non-empty."
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fi
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done
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# Make image smaller by not installing docs.
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DNF="dnf --setopt=tsflags=nodocs -y"
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for rpm in $(egrep -v '^(# )+' < /root/xpackages.txt); do
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x+="--exclude=$rpm ";
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done
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set -x # show what's happening to make debugging easier
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# DNF itself or a dependence may need upgrading, take care of it first.
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$DNF upgrade
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$DNF $x install \
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podman \
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systemd
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# Gitlab-runner package contains scriptlets which do not function properly inside a
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# container-build environment where systemd is not active/running.
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$DNF $x --setopt=tsflags=noscripts install \
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https://gitlab-runner-downloads.s3.amazonaws.com/$RUNNER_VERSION/rpm/gitlab-runner_${TARGETARCH}.rpm
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# Allow removing dnf, sudo, etc. packages. Also don't start unnecessary or broken
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# systemd services, like anything kernel related or login gettys.
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rm -rf \
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/etc/dnf/protected.d/* \
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/etc/sytemd/system/getty.target.wants/* \
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/etc/sytemd/system/multi-user.target.wants/* \
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/etc/sytemd/system/sysinit.target.wants/* \
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/etc/sytemd/system/timers.target.wants/* \
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/lib/systemd/system/graphical.target.wants/* \
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/lib/systemd/system/multi-user.target.wants/{getty.target,systemd-ask-password-wall.path} \
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/lib/systemd/system/sys-kernel*.mount
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# Remove unnecessary packages, see xpackages.txt to learn how this list was generated.
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# This makes the image smaller and reduces the attack-surface.
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dnf remove -y $(egrep -v '^(# )+' /root/xpackages.txt)
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# Wipe out the DNF cache, then remove it entirely, again to make the image smaller.
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$DNF clean all
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rm -rf /var/cache/dnf /var/log/dnf* /var/log/yum.*
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rpm -e dnf
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# Workaround https://bugzilla.redhat.com/show_bug.cgi?id=1995337
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rpm --setcaps shadow-utils
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# Prevent copying of skel since it can interfere with the gitlab-runner
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mkdir -p /home/podman /home/runner
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# Guarantee uid/gid 1000 for user 'podman' / 1001 for user 'runner'.
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groupadd -g 1000 podman
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groupadd -g 1001 runner
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# Separate users for services to increase process isolation.
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# The 'podman' user's socket service writes /home/runner/podman.socket
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useradd -M -u 1000 -g podman -G runner podman
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useradd -M -u 1001 -g runner runner
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# Allow 'podman' user to create socket file under /home/runner.
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chmod 770 /home/runner
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# Overwrite defaults, only user 'podman' permited to have a user-namespace
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# Split the namespaced ID's around the containers root (ID 0), podman (ID 1000), and
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# runner (ID 1001) such that the user-namespace of any nested containers cannot
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# read or write any files owned by these users (and/or hijack nested container processes).
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# N/B: The range-end (999+64536) ensures a total of 65535 IDs are available for nested-containers.
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# This requires the host provide a sufficiently large range, i.e. `pipglr:<start>:65539`
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echo -e "podman:1:999\npodman:1002:64536" | tee /etc/subuid > /etc/subgid
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# Host volume mount necessary for nested-podman to use overlayfs2 for container & volume storage.
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mkdir -p /home/podman/.local/share/containers
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# Nested-container's local container-cache volume mount, recommended by gitlab-runner docs.
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mkdir -p /cache
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# Both the gitlab-runner and podman need access to the cache directory / volume mount.
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chown podman:runner /cache
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# Setup persistent 'podman' user services to start & run without a login.
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mkdir -p /var/lib/systemd/linger
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touch /var/lib/systemd/linger/podman
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# Setup 'podman' socket and a container-storage pruning service for 'podman' user.
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mkdir -p /home/podman/.config/systemd/user/{sockets.target.wants,default.target.wants}
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cd /home/podman/.config/systemd/user/
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ln -s $PWD/podman.socket ./sockets.target.wants/ # Added from Containerfile
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ln -s $PWD/prune.timer ./default.target.wants/ # also from Containerfile
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# Substitute value from --build-arg if specified, otherwise use default from Containerfile.
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sed -i -e "s/@@@PRUNE_INTERVAL@@@/$PRUNE_INTERVAL/" ./prune.timer
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# Containerfile ADD instruction does not properly set ownership/permissions.
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chown -R 1000:1000 /home/podman
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chmod 700 /home/podman
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# Setup persistent 'runner' user services to start & run without a login.
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touch /var/lib/systemd/linger/runner
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mkdir -p /home/runner/.config/systemd/user/default.target.wants
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cd /home/runner/.config/systemd/user/
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# Does not depend on podman.socket file availablility, will retry if not present.
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ln -s $PWD/runner.service ./default.target.wants/
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# gitlab-runner will create side-car '.runner_system_id' file next to 'config.toml'
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# on first startup. Ensure access is allowed. Also link to future config file
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# presented as a container-secret.
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mkdir -p /home/runner/.gitlab-runner
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ln -s /var/run/secrets/config.toml /home/runner/.gitlab-runner/config.toml
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# Containerfile ADD instruction does not properly set ownership/permissions.
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chown -R runner:runner /home/runner
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chmod -R 700 /home/runner/.gitlab-runner
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