ansible-by-proxy

#!/usr/bin/env bash

set -e

HERE=$(dirname "$0")
HOST=$(basename "$0")
INVENTORY=${HERE}/ansible/inventory

function usage() {
  cat <<EOF >&2
Usage: ${HOST} [-n|--dry-run] {ansible-module} {arguments} -- [arguments]

or

Usage: ${HOST} [-n|--dry-run] [-r|--retry] {ansible-playbook} -- [arguments]

In the first form, the invocation expands to the following shell invocation:

    ansible -i ${INVENTORY} ${HOST} -m {ansible-module} -a {arguments} \
      [arguments]

In the second form, the invocation expands to:

    ansible-playbook -i ${INVENTORY} -l ${HOST} {ansible-playbook}

The {ansible-playbook} can be specified either as a filename relative to
${HERE}/ansible/ or as a full path or as the basename excluding the .yml
extension that refers to a file named ${HERE}/ansible/{ansible-playbook}.yml.

The second form also allows specifying a -r or --retry option that will further
limit the host selection based on a {ansible-playbook}.retry file that the
script expects to find adjacent to the playbook.

In both forms, the -n or --dry-run options cause the command to be printed
without executing.

The list of ansible playbooks that are available for use are:

EOF

  for pb in ${HERE}/ansible/*.yml ; do
    echo "     $(basename $pb)"
  done
  exit 1
}

if [[ "${HOST}" == "ansible-by-proxy" ]]; then
  cat <<EOF >&2
This script isn't meant to be invoked as-is. Instead create a symlink to this
script as follows:

  $ ln -s ansible-by-proxy groupname

... where "groupname" is a group defined in ${INVENTORY}.
EOF
  exit 1
fi

POSITIONAL=()
REST=()
while [[ $# -gt 0 ]]; do
  ARG=$1
  case $ARG in
    -h | --help )
      usage
      ;;

    -n | --dry-run | --dryrun )
      ANSIBLEPREFIX=echo
      shift
      ;;

    -r | --retry )
      RETRY=1
      shift
      ;;

    -- )
      shift
      REST=$@
      shift $#
      ;;

    -* )
      echo "Unrecognized option ${ARG}" >&2
      usage
      ;;

    * )
      if [[ ${#POSITIONAL[@]} -ge 2 ]]; then
        REST="$@"
        shift $#
      else
        POSITIONAL+=("$ARG")
        shift
      fi
      ;;
  esac
done

# Use pipelining instead of copying a script into the target VM. This saves us
# one SSH session.
export ANSIBLE_SSH_PIPELINING=True

# Free scheduling means that tasks are run on each host indepdently. The
# default is for all hosts to complete each step for the playbook to proceed to
# the next step.
export ANSIBLE_STRATEGY=free

# Improve readability of ansible output. The default is to spit out unformatted
# JSON.
# To get a list of callback plugins, use: ansible-doc -t callback -l
export ANSIBLE_STDOUT_CALLBACK=unixy

# Enable use of callback plugins for ad-hoc commands.
export ANSIBLE_LOAD_CALLBACK_PLUGINS=1

# Don't spam syslog.
export ANSIBLE_DEFAULT_NO_TARGET_SYSLOG=1

log_dir=${HOME}/log
log_name_suffix=$(date +%Y-%m-%d-%H-%M-%S)

if [[ ! -d ${log_dir} ]]; then
  mkdir -p ${log_dir}
fi

if [[ ${#POSITIONAL[@]} -eq 0 ]]; then
  usage
fi

if [[ ${#POSITIONAL[@]} -eq 2 ]]; then
  ${ANSIBLEPREFIX} ansible -i "${INVENTORY}" ${HOST} -m "${POSITIONAL[0]}" -a "${POSITIONAL[1]}" "${REST[@]}"

else
  MODULE=${POSITIONAL[0]}

  function prep_logging() {
    module_name=$(basename -s .yml ${MODULE})
    latest_log_name=${log_dir}/${module_name}-latest.log

    export ANSIBLE_LOG_PATH=${log_dir}/${module_name}-${log_name_suffix}.log

    if [[ -f ${latest_log_name} ]]; then
      rm ${latest_log_name}
    fi
    ln -s ${ANSIBLE_LOG_PATH} ${latest_log_name}
  }

  if [[ -n "$RETRY" ]]; then
    LIMIT="--limit @${HERE}/ansible/${MODULE}.retry"
  fi

  # If the second argument is a playbook specified either as a relative path,
  # or as just a playbook name, then we invoke the playbook and constrain the
  # host selection to $HOST.
  if [[ -f "${MODULE}" ]]; then
    prep_logging
    ${ANSIBLEPREFIX} ansible-playbook -i ${INVENTORY} --limit ${HOST} ${LIMIT} "${MODULE}" "${REST[@]}"
    echo Log written to ${ANSIBLE_LOG_PATH}

  elif [[ -f "${HERE}/ansible/${MODULE}.yml" ]]; then
    prep_logging
    ${ANSIBLEPREFIX} ansible-playbook -i ${INVENTORY} --limit ${HOST} ${LIMIT} "${HERE}/ansible/${MODULE}.yml" "${REST[@]}"

    echo Log written to ${ANSIBLE_LOG_PATH}

  # Otherwise, we treat it as an ad hoc command. MODULE now refers to an
  # ansible module, and the next non-switch parameter is the argument for that
  # module.
  else
    ${ANSIBLEPREFIX} ansible -i ${INVENTORY} ${HOST} -m ${MODULE} "${REST[@]}"
  fi
fi

if [[ "$(type -t alert)" == "function" ]]; then
  alert "Completed ${MODULE}"
fi