How to setup a Alpine Linux mirror

From Alpine Linux

Introduction

This document describes how to set up an Alpine Linux mirror and make it available via http and rsync.

We will:

  • create the dir where we have the mirror
  • set up a cron job to sync with master mirror every hour
  • set up lighttpd for http access
  • set up rsync so other mirrors can rsync from you

Make sure that you have enough disk space.

Current (2024-05-16) disk usage in GB:

edge v3.0 v3.1 v3.2 v3.3 v3.4 v3.5 v3.6 v3.7 v3.8 v3.9 v3.10 v3.11 v3.12 v3.13 v3.14 v3.15 v3.16 v3.17 v3.18 v3.19 v3.20 total
406 17 18 15 21 25 27 45 43 59 73 92 126 148 156 181 194 209 223 235 234 269 2809

Script used to calculate the size: 

#!/bin/sh

total=0
dest="$(mktemp -d)"

for dir in edge v3.0 v3.1 v3.2 v3.3 v3.4 v3.5 v3.6 v3.7 v3.8 v3.9 v3.10 v3.11 v3.12 v3.13 v3.14 v3.15 v3.16 v3.17 v3.18 v3.19 v3.20; do
    old_total="$total"
    src="rsync://rsync.alpinelinux.org/alpine/$dir/"
    size=$(rsync -a -n --stats "$src" "$dest" | grep '^Total file size' | tr -d ',' | awk '{ print $4 }')
    total=$(( old_total + size ))
    echo "$dir: $size" | awk '{ print $1 sprintf("%.1f", $2/1073741824) }'
done

echo "total: $total" | awk '{ print $1 sprintf("%.1f", $2/1073741824) }'
rm -r "$dest"

Setting up the cron job

Install rsync which will be used to sync from the master mirror.

apk add rsync

Save the following file as /etc/periodic/hourly/alpine-mirror 

#!/bin/sh

# make sure we never run 2 rsync at the same time
lockfile="/tmp/alpine-mirror.lock"
if [ -z "$flock" ] ; then
  exec env flock=1 flock -n $lockfile "$0" "$@"
fi

src=rsync://rsync.alpinelinux.org/alpine/ 
dest=/var/www/localhost/htdocs/alpine/

# uncomment this to exclude old v2.x branches
#exclude="--exclude v2.*"

mkdir -p "$dest"
/usr/bin/rsync \
        --archive \
        --update \
        --hard-links \
        --delete \
        --delete-after \
        --delay-updates \
        --timeout=600 \
        $exclude \
        "$src" "$dest"

(or use this script)

Make it executable:

chmod +x /etc/periodic/hourly/alpine-mirror

Now it will sync every hour. (given cron runs)

Setting up HTTP access via lighttpd

Install the lighttpd server

apk add lighttpd

Enable dir listings by uncommenting the following line in /etc/lighttpd/lighttpd.conf: 

dir-listing.activate      = "enable"

Also set cache-control to force cache revalidate every 30 mins. Uncomment mod_setenv in /etc/lighttpd/lighttpd.conf: 

"mod_setenv",

Add also the following lines to /etc/lighttpd/lighttpd.conf: 

setenv.add-response-header += (           
        "Cache-Control" => "must-revalidate"
)

Start lighttpd and make it start at boot:

rc-service lighttpd start rc-update add lighttpd

Note: You may wish to consider Darkhttpd as an alternative to Lighttpd

If so, simply install, start and auto-start the webserver:

apk add darkhttpd && rc-service darkhttpd start && rc-update add darkhttpd

Darkhttpd will, by default, offer directory listings and serve data from /var/www/localhost/htdocs/

See the main article on Darkhttpd for more configuration options

Setting up rsyncd

Add the following lines to /etc/rsyncd.conf: 

[alpine]
        path = /var/www/localhost/htdocs/alpine
        comment = My Alpine Linux Mirror

Optionally set a bandwidth limit in /etc/conf.d/rsyncd. In this example we limit to 500Kbytes/s (approx 5Mbit/s) 

RSYNC_OPTS="--bwlimit=500"

Mirror statistics

Simple bandwidth statistics can be generated with vnstat.

apk add vnstat

edit /etc/vnstat.conf and replace the interface name with the appropriate one.

Start vnstatd

rc-service vnstatd start

copy the following script to /etc/periodic/15min/stats and make sure your crond is running. please not that heredoc should be tab indented or the script will fail. A working copy can be found here: https://tpaste.us/RrMv 

#!/bin/sh

output="/var/www/localhost/htdocs/.stats"
nic="eth0"

generate_index() {
    cat <<-EOF
    <!doctype html>
    <html lang="en">
    <head>
        <meta charset="utf-8">
        <meta http-equiv="cache-control" content=no-cache">
        <meta http-equiv="refresh" content="3000">
        <title>Alpine Linux mirror statistics</title>
    </head>
    <body>
        <table border="0">
            <tr><td><img src="summary.png" alt="summary"></td><td><img src="hours.png" alt="hours"></td></tr>
            <tr><td rowspan="2"><img src="days.png" alt="days"></td><td><img src="top10.png" alt="top10"></td></tr>
            <tr><td><img src="months.png" alt="months"></td></tr>
        </table>
    </body>
    </html>
    EOF
}

if  [ ! -f "$output"/index.html ]; then
    mkdir -p $output
    generate_index > "$output"/index.html
fi

for type in hours days months top10 summary hsummary vsummary; do
    vnstati --${type} -i $nic -o $output/${type}.png
done

Update mirror from mqtt

If you want your mirror to be really uptodate compared to our master mirror you can subscribe to Alpine Linux message server "msg.alpinelinux.org" and check for upload messages. Add mqtt-exec to be able to execute processes when specific topics are being send.

apk add mqtt-exec

mqtt-exec supports running multiple time so we need to setup a specific config.

ln -s mqtt-exec /etc/init.d/mqtt-exec.sync-mirror

ln -s mqtt-exec /etc/conf.d/mqtt-exec.sync-mirror

edit /etc/conf.d/mqtt-exec.sync-mirror 

mqtt_topics="rsync/rsync.alpinelinux.org/#"
exec_user="buildozer"
exec_command="/usr/local/bin/sync-mirror"

Copy the following file to /usr/local/bin/sync-mirror and make it executable (dont forget to update the variables). 

#!/bin/sh

src="rsync://rsync.alpinelinux.org/alpine/"
dest="/var/www/localhost/htdocs/alpine/"
lock="/tmp/sync-mirror.lock"
topic="$1"
dir="$2"

[ -z "$flock" ] && exec env flock=1 flock $lock $0 "$@"

if [ -n "$dir" ] && [ -d "$dest/${dir%/*}" ]; then
    logger "Syncing directory: $dir"
    src="${src}${dir%/}/"
    dest="${dest}${dir%/}/"
else
    logger "Syncing all directories"
fi

/usr/bin/rsync \
    --archive \
    --update \
    --verbose \
    --progress \
    --timeout=600 \
    --delay-updates \
    --delete-after \
    "$src" \
    "$dest"

And finally start mqtt-exec and let it listen on msg.alpinelinux.org

rc-service mqtt-exec.sync-mirror start

To make sure you are not missing any packages (in case something goes wrong with MQTT subscription) you can periodically sync all directories by adding the script to cron.

ln -s /usr/local/bin/sync-mirror /etc/periodic/hourly/sync-mirror

Now watch your syslog as it should tell you when it will update directories in your local mirror.

Partial mirror using nginx

For a private mirror it might make sense to sync only the newest versions or some architectures of Alpine to save space, but if you do point an old Alpine version to your mirror they should still be able to install packages. We can achieve this by using nginx to serve the mirrored content and redirect all requests with 404 errors to a public mirror.

Let's assume you chose to only mirror Alpine versions up from v3.13. If a client asks your mirror for v.3.10 it should redirect to another mirror.

Your nginx config server block should look something like this: 

server {
        listen 80;
        server_name alpine.mydomain.local;
        root /data/alpine;          # point to where your alpine mirror is located. make sure nginx is allowed to read it
        autoindex on;               # Enable indexing

        error_page 404 = @alpinemirror;

        location @alpinemirror
        {
          return 302 http://dl-cdn.alpinelinux.org/alpine$request_uri;
        }
}

The corresponding sync script could look something like this: 

#!/bin/sh

# make sure we never run 2 rsync at the same time
lockfile="/tmp/alpine-mirror.lock"
if [ -z "$flock" ] ; then
  exec env flock=1 flock -n $lockfile "$0" "$@"
  fi

  src=rsync://rsync.alpinelinux.org/alpine/
  dest=/data/alpine/

  exclude="--exclude v2.* --exclude v3.0 --exclude v3.1 --exclude v3.2 --exclude v3.3 --exclude v3.4 --exclude v3.5 --exclude v3.6 --exclude v3.7 --exclude v3.8 --exclude v3.9 --exclude v3.10 --exclude v3.11 --exclude v3.12"

  mkdir -p "$dest"
  /usr/bin/rsync -vvv \
  --archive \
  --update \
  --hard-links \
  --delete \
  --delete-after \
  --delete-excluded \
  --delay-updates \
  --timeout=600 \
  $exclude \
  "$src" "$dest"
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