Singularity container for a Squid proxy

containers/EESSI-squid-proxy.def

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+BootStrap: docker
+From: centos:7
+
+%post
+    yum update -y
+    yum install -y squid which
+
+%environment
+    export LC_ALL=C
+
+%runscript
+    if [[ ${1:0:1} = '-' ]]; then
+        EXTRA_ARGS="$@"
+        set --
+    elif [[ ${1} == squid || ${1} == $(which squid) ]]; then
+        EXTRA_ARGS="${@:2}"
+        set --
+    fi
+
+    if [[ -z ${1} ]]; then
+        if [[ ! -d /var/spool/squid/00 ]]; then
+            echo "Initializing cache..."
+            $(which squid) -N -f /etc/squid/squid.conf -z
+        fi
+        echo "Starting squid..."
+        exec $(which squid) -f /etc/squid/squid.conf -NYCd 1 ${EXTRA_ARGS}
+    else
+        exec "$@"
+    fi
+
+%startscript
+    if [[ ${1:0:1} = '-' ]]; then
+        EXTRA_ARGS="$@"
+        set --
+    elif [[ ${1} == squid || ${1} == $(which squid) ]]; then
+        EXTRA_ARGS="${@:2}"
+        set --
+    fi
+
+    if [[ -z ${1} ]]; then
+        if [[ ! -d /var/spool/squid/00 ]]; then
+            echo "Initializing cache..."
+            $(which squid) -N -f /etc/squid/squid.conf -z
+        fi
+        echo "Starting squid..."
+        exec $(which squid) -f /etc/squid/squid.conf -NYCd 1 ${EXTRA_ARGS}
+    else
+        exec "$@"
+    fi

containers/README.md

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+# Containers
+This directory contains several Dockerfiles and Singularity definition files for different components,
+e.g. CVMFS clients and Squid proxies.
+
+## EESSI-squid-proxy.def: Singularity definition file for Squid proxy
+
+This definition file allows you to build a Singularity container that can be used for running a Squid proxy.
+
+### Build
+You can build the container using:
+```
+sudo singularity build EESSI-squid-proxy.sif EESSI-squid-proxy.def
+```
+### Configure
+Make some directories on the host for storing the cache, logs, and PID file:
+```
+mkdir -p /tmp/$USER/{var-log-squid,var-run,var-spool-squid,home}
+```
+
+Prepare a Squid configuration file, for instance based on our [Ansible template file](https://github.com/EESSI/filesystem-layer/blob/master/templates/eessi_localproxy_squid.conf.j2). Make sure that the ACLs and port number are configured correctly.
+
+Set the following environment variables to the correct local directories and configuration file:
+```
+export SINGULARITY_BIND="eessi_localproxy_squid.conf:/etc/squid/squid.conf,/tmp/$USER/var-run:/var/run,/tmp/$USER/var-log-squid:/var/log/squid,/tmp/$USER/var-spool-squid:/var/spool/squid"
+export SINGULARITY_HOME="/tmp/$USER/home:/home/$USER"
+```
+
+### Run
+
+Now start the container as a Singularity instance (which will run it like a service in the background):
+```
+singularity instance start EESSI-squid-proxy.sif cvmfs_proxy
+```
+
+The last argument defines the name for this instance, which can be used to connect a shell (`singularity shell instance://cvmfs_proxy`) or to stop the instance:
+```
+singularity instance stop cvmfs_proxy
+```
+
+If you want to interactively start the proxy, you can still do this using:
+```
+singularity run EESSI-squid-proxy.sif
+```